File r37/lisp/csl/html/r37_0248.html artifact 0408934461 part of check-in 9992369dd3

<A NAME=ATAN2>

<TITLE>ATAN2</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>ATAN2</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
<P>
 
<P>
<P>
 <P> <H3> 
syntax: </H3>
<em>atan2</em>(&lt;expression&gt;,&lt;expression&gt;) 
<P>
<P>
<P>
&lt;expression&gt; is any valid scalar REDUCE expression. In 

<A HREF=r37_0330.html>rounded</A> mode, if a numerical value exists, <em>atan2
</em> returns 
the principal value of the arc tangent of the second argument divided by 
the first in the range [-pi,+pi] radians, using the signs of both 
arguments to determine the quadrant of the return value. An expression in 
terms of <em>atan2</em> is returned in other cases. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
atan2(3,2); 

  ATAN2(3,2); 


on rounded; 

atan2(3,2); 

  0.982793723247 


atan2(a,b); 

  ATAN2(A,B); 


atan2(1,0); 

  1.57079632679

</TT></PRE><P><em>atan2</em>returns a numeric value only if 
<A HREF=r37_0330.html>rounded</A> is on. Then 
<em>atan2</em> is calculated to the current degree of floating point precision. 

<P>
<P>
<P>
<P>