[Go to CFHT Home Page] Man Pages
Back to Software Index  BORDER=0Manpage Top Level
    trig(3M) manual page Table of Contents

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 *p.

asin(x) returns the arc sine of x in the range -*p/2 to *p/2.

acos(x) returns the arc cosine of x in the range 0 to *p.

atan(x) returns the arc tangent of x in the range -*p/2 to
*p/2.

atan2(y,x) and hypot(x,y) (see hypot(3M) ) convert rectangular coordinates (x,y) to polar (r,*h); atan2(y,x) computes *h, the argument or phase, by computing an arc tangent of y/x in the range -*p to *p.

Return Values

For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by various Standards.

See Also

hypot(3M) , matherr(3M)

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(±if), cos(±if) and tan(±if) return NaN; asin(x) and acos(x) return NaN if |x|>1.
atan(±if) returns ±*p/2. For atan2(),
· atan2(±0,x) returns ±0 for x > 0 or x = +0;
· atan2(±0,x) returns ±*p for x < 0 or x = -0;
· atan2(y,±0) returns *p/2 for y > 0;
· atan2(y,±0) returns -*p/2 for y < 0;
· atan2(±y,if) returns ±0 for finite y > 0;
· atan2(±if,x) returns ±*p/2 for finite x;
· atan2(±y,-if) returns ±*p for finite y > 0;
· atan2(±if,if) returns ±*p/4;
· atan2(±if,-if) returns ±3*p/4.

Table of Contents