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<A NAME=PRECISE>

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



<B>PRECISE</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>switch</B><P>
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 <P>
<P>
When the <em>precise</em> switch is on, simplification of roots of even 
powers returns absolute values, a more precise answer mathematically. 
Default is <em>on</em>. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
sqrt(x**2); 

  X 


(x**2)**(1/4); 

  SQRT(X) 


on precise; 

sqrt(x**2); 

  ABS(X) 


(x**2)**(1/4); 

  SQRT(ABS(X))

</TT></PRE><P>In many types of mathematical work, simplification of powers and s
urds can 
proceed by the fastest means of simplifying the exponents arithmetically. 
When it is important to you that the positive root be returned, turn 
<em>precise</em> on. One situation where this is important is when graphing 
square-root expressions such as sqrt(x^2+y^2) to 
avoid a spike caused by REDUCE simplifying 
sqrt(y^2) to y when x is 
zero. 
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<P>
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