.\" Generated by the Allegro makedoc utility
.TH fixatan2 3alleg4 "version 4.4.3" "Allegro" "Allegro manual"
.SH NAME
fixatan2 \- Fixed point version of the libc atan2() routine. Allegro game programming library.\&
.SH SYNOPSIS
.B #include <allegro.h>

.sp
.B fixed fixatan2(fixed y, fixed x);
.SH DESCRIPTION
This is a fixed point version of the libc atan2() routine. It computes the
arc tangent of `y / x', but the signs of both arguments are used to
determine the quadrant of the result, and `x' is permitted to be zero. This
function is useful to convert Cartesian coordinates to polar coordinates.
Example:

.nf
   fixed result;
   
   /* Sets `result' to binary angle 64. */
   result = fixatan2(itofix(1), 0);
   /* Sets `result' to binary angle -109. */
   result = fixatan2(itofix(-1), itofix(-2));
   /* Fails the assert. */
   result = fixatan2(0, 0);
   ASSERT(!errno);
.fi
.SH "RETURN VALUE"
Returns the arc tangent of `y / x' in fixed point binary format angle,
from `-128' to `128'. If both `x' and `y' are zero, returns zero and sets
`errno' to EDOM.

.SH SEE ALSO
,
.BR exlights (3alleg4),
.BR exspline (3alleg4)