atan2d64.3m (2010 09)

a
atan2d64(3M) atan2d64(3M)
(HP Integrity Server Only)
NAME
atan2d64(), atan2d128(), atan2d32() - decimal arctangent and quadrant functions
SYNOPSIS
#define __STDC_WANT_DEC_FP__
#include <math.h>
_Decimal64 atan2d64(_Decimal64 x, _Decimal64 y);
_Decimal128 atan2d128(_Decimal128 x, _Decimal128 y);
_Decimal32 atan2d32(_Decimal32 x, _Decimal32 y);
DESCRIPTION
The atan2d64() function returns the arctangent of y/x, in the range −π to π, using the signs of both
arguments to determine the quadrant of the return value.
atan2d128() is a _Decimal128 version of atan2d64(); it takes
_Decimal128 arguments and
returns a
_Decimal128 result.
atan2d32() is a _Decimal32 version of atan2d64(); it takes
_Decimal32 arguments and returns
a
_Decimal32 result.
These math functions are supported for HP-UX 11i Version 3 September 2008 Update and forward.
USAGE
To use any of these functions, compile with the
+decfp option.
Make sure your program defines
__STDC_WANT_DEC_FP__
and then includes <math.h>.
Link in the math library by specifying
-lm or -l:libm.a on the linking command line.
For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site:
http://www.hp.com/go/fp
.
RETURN VALUE
If y is ±0 and x is −0,
atan2d64() returns ±π respectively.
If y is ±0 and x is +0,
atan2d64() returns ±0 respectively.
If y is ±0 and x is less than 0,
atan2d64() returns returns ±π respectively.
If y is ±0 and x is greater than 0,
atan2d64() returns returns ±0 respectively.
If y is less than 0 and x is 0,
atan2d64() returns −π/2.
If y is greater than 0 and x is 0,
atan2d64() returns π/2.
If y is greater than 0 and x is −infinity,
atan2d64() returns π.
If y is less than 0 and x is −infinity,
atan2d64() returns −π.
If y is greater than 0 and x is infinity,
atan2d64() returns +0.
If y is less than 0 and x is infinity,
atan2d64() returns −0.
If y is ±infinity and x is finite,
atan2d64() returns ±π/2 respectively.
If y is ±infinity and x is −infinity,
atan2d64() returns ±3π/4 respectively.
If y is ±infinity and x is +infinity,
atan2d64() returns ±π/4 respectively.
If x or y is NaN,
atan2d64() returns NaN.
atan2d64() raises the inexact exception whenever a rounded result does not equal the mathematical
result.
ERRORS
No errors are defined.
SEE ALSO
acosd64(3M), asind64(3M), atand64(3M), cosd64(3M), sind64(3M), tand64(3M), math(5).
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1