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<A NAME=s_i>

<TITLE>s_i</TITLE></A>
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<B>S_I</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
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The <em>s_i</em> operator returns the Sine Integral function si. 
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syntax: </H3>
<em>s_i</em>(&lt;expression&gt;) 
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examples: </H3>
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s_i(xx); 

  (2*Si(xx) - pi) / 2 


df(s_i(x),x); 

  sin(x) / x

</TT></PRE><P>The operator name <em>s_i</em> is simplified towards 
<A HREF=r37_0509.html>SI</A>. 
Since REDUCE is not case sensitive by default the name ``si'' can't be 
used. 
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