NAME

sin, cos, tan, asin, acos, atan, atan2 − trigonometric functions

SYNOPSIS

#include <math.h>

double sin(x)
double x;

double cos(x)
double x;

double asin(x)
double x;

double acos(x)
double x;

double atan(x)
double x;

double atan2(x, y)
double x, y;

DESCRIPTION

Sin, cos and tan return trigonometric functions of radian arguments.  The magnitude of the argument should be checked by the caller to make sure the result is meaningful. 

Asin returns the arc sin in the range −pi/2 to pi/2. 

Acos returns the arc cosine in the range 0 to pi. 

Atan returns the arc tangent of x in the range −pi/2 to pi/2. 

Atan2 returns the arc tangent of x/y in the range −pi to pi. 

DIAGNOSTICS

Arguments of magnitude greater than 1 cause asin and acos to return value 0; errno is set to EDOM.  The value of tan at its singular points is a huge number, and errno is set to ERANGE. 

BUGS

The value of tan for arguments greater than about 2**31 is garbage. 

7th Edition