Reference

atanpi(3)

half-cycle arc tangent functions

NAME

atanpi, atanpif, atanpil – half-cycle arc tangent functions

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double

atanpi(double x);

float

atanpif(float x);

long double

atanpil(long double x);

DESCRIPTION

The atanpi(), atanpif(), and atanpil() functions compute the principal value of the arc tangent of x, divided by , thus measuring the angle in half-cycles.

RETURN VALUES

The atanpi(), atanpif(), and atanpil()
functions return values in the range [-1/2, +1/2].

SEE ALSO

acospi(3), asinpi(3), atan(3), tanpi(3),

STANDARDS

The atanpi(), atanpif(), and atanpil() functions conform to ISO/IEC 9899:2024 (“ISO C23”).