trig(3M)
NAME
trig, sin, cos, tan, asin, acos, atan, atan2 − trigonometric functions
SYNOPSIS
cc [ flag ... ] file ... −lm [ library ... ]
#include <math.h>
double sin(double x);
double cos(double x);
double tan(double x);
double asin(double x);
double acos(double x);
double atan(double x);
double atan2(double y, double x);
MT-LEVEL
MT-Safe
DESCRIPTION
sin(x), cos(x) and tan(x) return trigonometric functions of radian arguments. Trigonometric argument reduction is carried out with respect to the infinitely precise π.
asin(x) returns the arc sine of x in the range −π/2 to π/2.
acos(x) returns the arc cosine of x in the range 0 to π.
atan(x) returns the arc tangent of x in the range −π/2 to π/2.
atan2(y,x) and hypot(x,y) (see hypot(3M)) convert rectangular coordinates (x,y) to polar (r,θ); atan2(y,x) computes θ, the argument or phase, by computing an arc tangent of y/x in the range −π to π.
RETURN VALUES
For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by various Standards.
SEE ALSO
DIAGNOSTICS
In IEEE754 mode (i.e. the −xlibmieee cc compilation option), these functions handle exceptional arguments in the spirit of ANSI/IEEE Std 754-1985. sin(±∞), cos(±∞) and tan(±∞) return NaN; asin(x) and acos(x) return NaN if |x|>1. atan(±∞) returns ±π/2. For atan2(),
• atan2(±0,x) returns ±0 for x > 0 or x = +0;
• atan2(±0,x) returns ±π for x < 0 or x = −0;
• atan2(y,±0) returns π/2 for y > 0;
• atan2(y,±0) returns −π/2 for y < 0;
• atan2(±y,∞) returns ±0 for finite y > 0;
• atan2(±∞,x) returns ±π/2 for finite x;
• atan2(±y,−∞) returns ±π for finite y > 0;
• atan2(±∞,∞) returns ±π/4;
• atan2(±∞,−∞) returns ±3π/4.
SunOS 5.5/x86 — Last change: 4 Mar 1994