Reference

acospi(3)

half-cycle arc cosine functions

NAME

acospi, acospif, acospil – half-cycle arc cosine functions

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double

acospi(double x);

float

acospif(float x);

long double

acospil(long double x);

DESCRIPTION

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 .

SEE ALSO

acos(3), asinpi(3), atanpi(3), cospi(3)

STANDARDS

The acospi(), acospif(), and acospil() functions conform to ISO/IEC 9899:2024 (“ISO C23”).