ACOS(3) - man page online | library functions

Arc cosine function.

ACOS(3)                             Linux Programmer's Manual                             ACOS(3)

NAME acos, acosf, acosl - arc cosine function
SYNOPSIS #include <math.h> double acos(double x); float acosf(float x); long double acosl(long double x); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): acosf(), acosl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99
DESCRIPTION These functions calculate the arc cosine of x; that is the value whose cosine is x.
RETURN VALUE On success, these functions return the arc cosine of x in radians; the return value is in the range [0, pi]. If x is a NaN, a NaN is returned. If x is +1, +0 is returned. If x is positive infinity or negative infinity, a domain error occurs, and a NaN is returned. If x is outside the range [-1, 1], a domain error occurs, and a NaN is returned.
ERRORS See math_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Domain error: x is outside the range [-1, 1] errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.
ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌─────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├─────────────────────────┼───────────────┼─────────┤ │acos(), acosf(), acosl() │ Thread safety │ MT-Safe │ └─────────────────────────┴───────────────┴─────────┘
CONFORMING TO C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD, C89.
SEE ALSO asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
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2015-04-19 ACOS(3)
This manual Reference Other manuals
acos(3) referred by asin(3) | atan(3) | atan2(3) | cos(3) | sin(3) | tan(3)
refer to asin(3) | atan(3) | atan2(3) | attributes(7) | cacos(3) | cos(3) | feature_test_macros(7) | math_error(7) | sin(3) | tan(3)