acospif3
Half-cycle arc cosine functions
Part of acospi(3).
Usage
#include <math.h>
double
acospi(double x);
float
acospif(float x);
long double
acospil(long double x);
Library
Math Library (libm, -lm)
Overview
The acospi(), acospif(), and acospil() functions compute the principal value of the arc cosine of x, divided by , thus measuring the angle in half-cycles.
Return values
The acospi(), acospif(), and acospil() functions return values in the range [-1, +1]. If |x| > 1, acospi(x) raise an invalid exception and returns an .