NAME

tanpi, tanpif, tanpil —

half–cycle tangent functions

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double
tanpi(double x);

float
tanpif(float x);

long double
tanpil(long double x);

DESCRIPTION

The tanpi(), tanpif(), and tanpil() functions compute the tangent of π × x and measure angles in half-cycles.

RETURN VALUES

The tanpi(), tanpif(), and tanpil() functions returns tan(π × x). If |x| ≥ 2^(p - 1) where p is the floating–point precision of x, then the returned value is ±0 and it has no significance.

SPECIAL VALUES

: tanpi(±0) returns ±0.
: tanpi(±n) returns ±0 for positive integers n.
: tanpi(±n/2) returns NaN for n > 0 and raises an FE_INVALID exception.
: tanpi(±∞) return an NaN and raises an FE_INVALID exception.
: tanpi(NaN) return an NaN and raises an FE_INVALID exception.

AUTHORS

The half–cycle trignometric functions were written by Steven G. Kargl <kargl@FreeBSD.org>.

STANDARDS

These functions conform to IEEE Std 754™–2008 , "IEEE Standard for Floating-Point Arithmetic" and to ISO/IEC TS 18661-4 , "Information technology — Programming languages, their environments, and system software interfaces — Floating–point extensions for C" — Part 4: Supplementary functions.