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 -π/2 to

     π/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 -π to π.



DIAGNOSTIC

     There is no error return.



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