    ATAN(III)                    4/30/73                    ATAN(III)

    NAME
         atan, atan2 - arc tangent function

    SYNOPSIS
         jsr    pc,atan[2]

         double atan(x)
         double x;

         double atan2(x, y)
         double x, y;

    DESCRIPTION
         The  atan  entry returns the arc tangent of fr0 in fr0; from
         C, the arc tangent of x is returned.  The range is  -J/2  to
         J/2.   The atan2 entry returns the arc tangent of fr0/fr1 in
         fr0; from C, the arc tangent of x/y is returned.  The  range
         is -J to .

    DIAGNOSTIC
         There is no error return.

    BUGS

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