acos

Date:: 09-08-2011

NAME

ACOS, DACOS, QACOS, ACOSD, DACOSD, QACOSD, acosf, acos, acosl, acosq - Arccosine (inverse cosine) function

SYNOPSIS

C Synopsis

#include <math.h>
float acosf(float);
double acos(double);
long double acosl(long double);

#include <quadmath.h>
__float128 acosq(__float128);

Fortran Synopsis

ACOS ([X=]x)
DACOS ([X=]x)
QACOS ([X=]x)
ACOSD ([X=]x) (Deferred implementation)
DACOSD ([X=]x) (Deferred implementation)
QACOSD ([X=]x) (Deferred implementation)

Cray Extensions

acosq, QACOS, DACOSD, QACOSD

DESCRIPTION

Return the arccosine of x (the angle whose cosine is x).

Fortran

These are elemental intrinsic functions. The Fortran ACOS and ACOSD functions are generic; they accept real or complex arguments of any size. The others are specific. See the RETURN VALUES section for more information on input data types and return values.

For ACOS, DACOS, and QACOS, the result is in radians.

For ACOSD, DACOSD, and QACOSD, the result is in degrees.

C

The C functions accept double or floating point argument types as specified in the synopsis. Results are in radians.

NOTES

The ACOS, DACOS, and QACOS intrinsic function names can be passed as arguments; the others cannot.

ACOS(x) yields NaN if |x| is > 1 or NaN.

Fortran (kind=16) quad-precision is always 128 bits. Double precision may also be 128 bits if -ep -sdefault64 or -ep -sreal64 is specified on the command line.

RETURN VALUES

ACOS and ACOSD return the real arccosine of their real arguments.

DACOS and DACOSD return the double-precision arccosine of their double-precision arguments.

QACOS and QACOSD return the quad-precision arccosine of their quad-precision arguments.