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	<title>Distance formula for inverse stereographic projection - Revision history</title>
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	<updated>2026-06-09T07:26:58Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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		<id>https://companal.subwiki.org/w/index.php?title=Distance_formula_for_inverse_stereographic_projection&amp;diff=145&amp;oldid=prev</id>
		<title>Vipul: 1 revision</title>
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		<updated>2008-05-18T19:12:25Z</updated>

		<summary type="html">&lt;p&gt;1 revision&lt;/p&gt;
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				&lt;td colspan=&quot;1&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;1&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 19:12, 18 May 2008&lt;/td&gt;
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		<author><name>Vipul</name></author>
	</entry>
	<entry>
		<id>https://companal.subwiki.org/w/index.php?title=Distance_formula_for_inverse_stereographic_projection&amp;diff=144&amp;oldid=prev</id>
		<title>Vipul: New page: ==Statement==  Consider the inverse stereographic projection map:  &lt;math&gt;\Phi:\mathbb{C} \to S^2 \setminus \{ N \}&lt;/math&gt;  where &lt;math&gt;N&lt;/math&gt; is the north pole in &lt;math&gt;S^2&lt;/math&gt;.  ...</title>
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		<updated>2008-04-27T14:36:25Z</updated>

		<summary type="html">&lt;p&gt;New page: ==Statement==  Consider the inverse &lt;a href=&quot;/wiki/Stereographic_projection&quot; title=&quot;Stereographic projection&quot;&gt;stereographic projection&lt;/a&gt; map:  &amp;lt;math&amp;gt;\Phi:\mathbb{C} \to S^2 \setminus \{ N \}&amp;lt;/math&amp;gt;  where &amp;lt;math&amp;gt;N&amp;lt;/math&amp;gt; is the north pole in &amp;lt;math&amp;gt;S^2&amp;lt;/math&amp;gt;.  ...&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;==Statement==&lt;br /&gt;
&lt;br /&gt;
Consider the inverse [[stereographic projection]] map:&lt;br /&gt;
&lt;br /&gt;
&amp;lt;math&amp;gt;\Phi:\mathbb{C} \to S^2 \setminus \{ N \}&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
where &amp;lt;math&amp;gt;N&amp;lt;/math&amp;gt; is the north pole in &amp;lt;math&amp;gt;S^2&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
Then the distance in &amp;lt;math&amp;gt;\R^3&amp;lt;/math&amp;gt; between &amp;lt;math&amp;gt;\Phi(z)&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;\Phi(w)&amp;lt;/math&amp;gt; is given by:&lt;br /&gt;
&lt;br /&gt;
&amp;lt;math&amp;gt;\frac{|z - w|}{(1 + |z|^2)(1 + |w|^2)}&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
==Facts used==&lt;br /&gt;
&lt;br /&gt;
We use here the formula for inverse stereographic projection:&lt;br /&gt;
&lt;br /&gt;
&amp;lt;math&amp;gt;\Phi(z) = \left(\frac{z + \overline{z}}{1 + |z|^2}, \frac{z - \overline{z}}{i(1 + |z|^2)}, \frac{|z|^2 - 1}{1 + |z|^2}\right)&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
==Proof==&lt;br /&gt;
&lt;br /&gt;
We simply plug in the formula for &amp;lt;math&amp;gt;\Phi(z), \Phi(w)&amp;lt;/math&amp;gt; in the formula to calculate the distance between two points in Euclidean space. {{fillin}}&lt;/div&gt;</summary>
		<author><name>Vipul</name></author>
	</entry>
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