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		<updated>2026-04-22T06:23:46Z</updated>
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	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2415&amp;oldid=prev</id>
		<title>Dattorro at 02:23, 6 November 2010</title>
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				<updated>2010-11-06T02:23:30Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
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			&lt;col class='diff-content' /&gt;
			&lt;tr&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 02:23, 6 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Nonnegative rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes directly from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Nonnegative rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes directly from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means, the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\!\in\mathbb{R}^{262144}&lt;/ins&gt;&amp;lt;/math&amp;gt; denotes vectorization; it means, the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\!\in\!\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\!\in\!\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;It contains only &lt;/del&gt;integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}\,&amp;lt;/math&amp;gt;.&amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;All its entries are &lt;/ins&gt;integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}\,&amp;lt;/math&amp;gt;.&amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The 2 appears only in the fifth row from the bottom of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The 2 appears only in the fifth row from the bottom of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2414&amp;oldid=prev</id>
		<title>Dattorro at 02:19, 6 November 2010</title>
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				<updated>2010-11-06T02:19:48Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 02:19, 6 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 8:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 8:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Rectangular &lt;/del&gt;submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Nonnegative rectangular &lt;/ins&gt;submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;directly &lt;/ins&gt;from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means, the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means, the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2413&amp;oldid=prev</id>
		<title>Dattorro at 02:19, 6 November 2010</title>
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				<updated>2010-11-06T02:19:07Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
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			&lt;col class='diff-content' /&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 02:19, 6 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 23:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 23:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;, for your purposes, but leave a hook for it in case you require another value.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;, for your purposes, but leave a hook for it in case you require another value.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before numerical solution begins. &amp;amp;nbsp;  The [http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat Matlab binary] possesses all 262,144 columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;in &lt;/del&gt;a presolve.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before numerical solution begins. &amp;amp;nbsp;  The [http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat Matlab binary] possesses all 262,144 columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;yet &lt;/ins&gt;been discarded &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;by &lt;/ins&gt;a presolve.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2412&amp;oldid=prev</id>
		<title>Dattorro at 02:17, 6 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2412&amp;oldid=prev"/>
				<updated>2010-11-06T02:17:32Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 02:17, 6 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 18:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 18:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;containing &lt;/del&gt;matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;is &lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat &lt;/ins&gt;Matlab binary&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;] contains &lt;/ins&gt;matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt;. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here]&lt;/del&gt;. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified because I want to vary it later as part of a &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified because I want to vary it later as part of a &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;convex iteration&lt;/del&gt;. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;[[Convex Iteration]]&lt;/ins&gt;. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;, for your purposes, but leave a hook for it in case you require another value.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;, for your purposes, but leave a hook for it in case you require another value.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2411&amp;oldid=prev</id>
		<title>Dattorro at 02:14, 6 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2411&amp;oldid=prev"/>
				<updated>2010-11-06T02:14:50Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 02:14, 6 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;, &lt;/ins&gt;the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\!\in\!\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\!\in\!\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;only &lt;/del&gt;contains integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It contains &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;only &lt;/ins&gt;integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\,&amp;lt;/math&amp;gt;.&amp;amp;nbsp;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;The 2 appears only in the fifth row from the bottom of &amp;lt;math&amp;gt;A&lt;/ins&gt;\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 19:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 20:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary containing matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; is &lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary containing matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; is &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here]. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here]. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;beause &lt;/del&gt;I &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;may &lt;/del&gt;want to vary it later &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;in &lt;/del&gt;a convex iteration. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;because &lt;/ins&gt;I want to vary it later &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;as part of &lt;/ins&gt;a convex iteration. &amp;amp;nbsp;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;For your purposes, &lt;/del&gt;&amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Vector &lt;/ins&gt;&amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;, &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;for your purposes&lt;/ins&gt;, &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;but leave a hook for it &lt;/ins&gt;in &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;case you require another value&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A good presolver can eliminate about 50&lt;/del&gt;,&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;000 columns of &amp;lt;math&amp;gt;\&lt;/del&gt;,&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries &lt;/del&gt;in &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before numerical solution begins. &amp;amp;nbsp;  The Matlab binary above possesses all columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before numerical solution begins. &amp;amp;nbsp;  The [http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat Matlab binary] possesses all 262,144 columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded in a presolve.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2408&amp;oldid=prev</id>
		<title>Dattorro at 11:28, 5 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2408&amp;oldid=prev"/>
				<updated>2010-11-05T11:28:13Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 11:28, 5 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 22:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 22:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &amp;amp;nbsp;  The Matlab binary above &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;has &lt;/del&gt;all columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;numerical &lt;/ins&gt;solution begins. &amp;amp;nbsp;  The Matlab binary above &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;possesses &lt;/ins&gt;all columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2407&amp;oldid=prev</id>
		<title>Dattorro at 11:21, 5 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2407&amp;oldid=prev"/>
				<updated>2010-11-05T11:21:13Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 11:21, 5 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;I regard the following as a difficult problem, having spent considerable time with it.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;I regard the following as a &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;very &lt;/ins&gt;difficult problem, having spent considerable time with it.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 8:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 8:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;. &amp;amp;nbsp;  This discard occurs because of structural redundancy in &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt;&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\in\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\!&lt;/ins&gt;\in&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\!&lt;/ins&gt;\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros. &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;&amp;amp;nbsp;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It contains integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;only &lt;/ins&gt;contains integers from the set &amp;lt;math&amp;gt;\{{-1},0,1,2\}\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries.  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary containing matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; is &lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary containing matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; is &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here].&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here]. &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;&amp;amp;nbsp;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration. &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;&amp;amp;nbsp;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;it &lt;/del&gt;may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; &lt;/ins&gt;may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries. &amp;amp;nbsp;  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &amp;amp;nbsp;  The Matlab binary above has all columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt;; &amp;amp;nbsp; none of its columns have been discarded.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2406&amp;oldid=prev</id>
		<title>Dattorro at 11:07, 5 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2406&amp;oldid=prev"/>
				<updated>2010-11-05T11:07:07Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

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				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 11:07, 5 November 2010&lt;/td&gt;
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		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 7:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 7:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;amp;X\geq_{}\mathbf{0}\end{array}&amp;lt;/math&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;amp;X\geq_{}\mathbf{0}\end{array}&amp;lt;/math&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;/center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration.&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, it may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\!\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four consecutive columns discarded.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 21:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 18:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries.  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about 50,000 columns of &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; because one of the constraints '''('''fifth row from the bottom of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;''')''' has only nonnegative entries.  This means that about 50,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A Matlab binary containing matrices &amp;lt;math&amp;gt;\,A&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\,b&amp;lt;/math&amp;gt; is &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[http://www.convexoptimization.com/TOOLS/Wotao.Yin/WotaoX.mat here].&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, it may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2405&amp;oldid=prev</id>
		<title>Dattorro at 10:57, 5 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2405&amp;oldid=prev"/>
				<updated>2010-11-05T10:57:30Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;tr&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 10:57, 5 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 11:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 11:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, it may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;For your purposes, it may arbitrarily be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;square &lt;/del&gt;permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;consecutive &lt;/del&gt;four columns discarded.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular submatrix &amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a permutation matrix &amp;lt;math&amp;gt;\,\Xi\!\in&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\!&lt;/ins&gt;\mathbb{R}^{1024\times1024}\,&amp;lt;/math&amp;gt; having three out of every four &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;consecutive &lt;/ins&gt;columns discarded&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Notation &amp;lt;math&amp;gt;\mbox{vec}\,X&amp;lt;/math&amp;gt; denotes vectorization; it means the columns of &amp;lt;math&amp;gt;\,X&amp;lt;/math&amp;gt; are stacked with column 1 on top and column 256 on the bottom&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\in\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Matrix &amp;lt;math&amp;gt;A\in\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It contains integers from the set &amp;lt;math&amp;gt;\{-1,0,1,2\}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;It contains integers from the set &amp;lt;math&amp;gt;\&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;{&lt;/ins&gt;{-1&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;}&lt;/ins&gt;,0,1,2\}&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\,&lt;/ins&gt;&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;: &amp;lt;math&amp;gt;1\,&amp;lt;/math&amp;gt;&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;60&lt;/del&gt;,000 columns of &amp;lt;math&amp;gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A&lt;/del&gt;\,&amp;lt;/math&amp;gt; because one of the constraints (fifth row from the bottom) has &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;all &lt;/del&gt;nonnegative entries.  This means that about &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;60&lt;/del&gt;,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;A good presolver can eliminate about &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;50&lt;/ins&gt;,000 columns of &amp;lt;math&amp;gt;\,&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A&lt;/ins&gt;&amp;lt;/math&amp;gt; because one of the constraints &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;'''&lt;/ins&gt;(&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;'''&lt;/ins&gt;fifth row from the bottom &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;of &amp;lt;math&amp;gt;\,A\,&amp;lt;/math&amp;gt;'''&lt;/ins&gt;)&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;''' &lt;/ins&gt;has &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;only &lt;/ins&gt;nonnegative entries.  This means that about &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;50&lt;/ins&gt;,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins. &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

	<entry>
		<id>http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2404&amp;oldid=prev</id>
		<title>Dattorro at 10:43, 5 November 2010</title>
		<link rel="alternate" type="text/html" href="http://www.convexoptimization.com/wikimization/index.php?title=User_talk:Wotao.yin&amp;diff=2404&amp;oldid=prev"/>
				<updated>2010-11-05T10:43:57Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;

			&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;tr&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;←Older revision&lt;/td&gt;
				&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 10:43, 5 November 2010&lt;/td&gt;
			&lt;/tr&gt;
		&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Wotao&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;I regard the following as a difficult problem, having spent considerable time &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;with &lt;/ins&gt;it.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;I regard the following as a difficult problem, having spent considerable time &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;on &lt;/del&gt;it.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;lt;center&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 11:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 9:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Vector &amp;lt;math&amp;gt;c\,&amp;lt;/math&amp;gt; is left unspecified beause I may want to vary it later in a convex iteration.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;To start&lt;/del&gt;, it may be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;For your purposes&lt;/ins&gt;, it may &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;arbitrarily &lt;/ins&gt;be set to &amp;lt;math&amp;gt;\mathbf{0}&amp;lt;/math&amp;gt; or &amp;lt;math&amp;gt;\mathbf{1}&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;-&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular &lt;del style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;matrix &lt;/del&gt;&amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a square permutation matrix &amp;lt;math&amp;gt;\Xi\,&amp;lt;/math&amp;gt; having three out of every consecutive four columns discarded.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Rectangular &lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;submatrix &lt;/ins&gt;&amp;lt;math&amp;gt;\,X\!\in\mathbb{R}^{1024\times256}\,&amp;lt;/math&amp;gt; comes from a square permutation matrix &amp;lt;math&amp;gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\,&lt;/ins&gt;\Xi&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;\!\in\mathbb{R}^{1024\times1024}&lt;/ins&gt;\,&amp;lt;/math&amp;gt; having three out of every consecutive four columns discarded&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Matrix &amp;lt;math&amp;gt;A\in\mathbb{R}^{10565\times262144}&amp;lt;/math&amp;gt; is sparse having only 979,444 nonzeros.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;It contains integers from the set &amp;lt;math&amp;gt;\{-1,0,1,2\}&amp;lt;/math&amp;gt;.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;Vector &amp;lt;math&amp;gt;b\,&amp;lt;/math&amp;gt; is quite sparse having only a single nonzero entry.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;nbsp;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;color: red; font-weight: bold; text-decoration: none;&quot;&gt;A good presolver can eliminate about 60,000 columns of &amp;lt;math&amp;gt;A\,&amp;lt;/math&amp;gt; because one of the constraints (fifth row from the bottom) has all nonnegative entries.  This means that about 60,000 entries in permutation submatrix &amp;lt;math&amp;gt;X\,&amp;lt;/math&amp;gt; can be set to zero before solution begins&lt;/ins&gt;. &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt; &lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;--[[User:Dattorro|Dattorro]] 03:31, 5 November 2010 (PDT)&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Dattorro</name></author>	</entry>

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