ACOS(3) BSD Programmer's Manual ACOS(3)
acos, acosf - arc cosine function
libm
#include <math.h> double acos(double x); float acosf(float x);
The acos() and acosf() functions compute the principal value of the arc cosine of x in the range [0, pi].
If |x|>1, acos(x) and acosf(x) set the global variable errno to EDOM.
asin(3), atan(3), atan2(3), cos(3), cosh(3), math(3), sin(3), sinh(3), tan(3), tanh(3)
The acos() function conforms to ANSI X3.159-1989 ("ANSI C89"). MirBSD #10-current May 2, 1991 1