
<A NAME=I>

<TITLE>I</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>I</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>constant</B><P>
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REDUCE knows <em>i</em> is the square root of -1, 
 and that i^2 = -1. 
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 <P> <H3> 
examples: </H3>
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(a + b*i)*(c + d*i); 

  A*C + A*D*I + B*C*I - B*D 


i**2; 

  -1

</TT></PRE><P><em>i</em>cannot be used as an identifier. It is all right to use 
<em>i</em> 
as an index variable in a <em>for</em> loop, or as a local (<em>scalar</em>) 
variable inside a <em>begin...end</em> block, but it loses its definition as 
the square root of -1 inside the block in that case. 
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Only the simplest properties of i are known by REDUCE unless 
the switch 
<A HREF=r37_0274.html>complex</A> is turned on, which implements full complex 
arithmetic in factoring, simplification, and functional values. 
<em>complex</em> is ordinarily off. 
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