TRIG(3M) (Math Libraries) TRIG(3M)
NAME
trig: sin, cos, tan, asin, acos, atan, atan2 - trigonometric
functions
SYNOPSIS
#include <math.h>
double sin (x)
double x;
double cos (x)
double x;
double tan (x)
double x;
double asin (x)
double x;
double acos (x)
double x;
double atan (x)
double x;
double atan2 (y, x)
double y, x;
DESCRIPTION
Sin, cos and tan return respectively the sine, cosine and
tangent of their argument, x, measured in radians.
Asin returns the arcsine of x, in the range [-π/2,π/2].
Acos returns the arccosine of x, in the range [0,π].
Atan returns the arctangent of x, in the range [-π/2,π/2].
Atan2 returns the arctangent of y/x, in the range (-π,π],
using the signs of both arguments to determine the quadrant
Page 1 May 1989
TRIG(3M) (Math Libraries) TRIG(3M)
of the return value.
SEE ALSO
matherr(3M).
DIAGNOSTICS
Sin, cos, and tan lose accuracy when their argument is far
from zero. For arguments sufficiently large, these
functions return zero when there would otherwise be a
complete loss of significance. In this case a message
indicating TLOSS error is printed on the standard error
output. For less extreme arguments causing partial loss of
significance, a PLOSS error is generated but no message is
printed. In both cases, errno is set to ERANGE.
If the magnitude of the argument of asin or acos is greater
than one, or if both arguments of atan2 are zero, zero is
returned and errno is set to EDOM. In addition, a message
indicating DOMAIN error is printed on the standard error
output.
These error-handling procedures may be changed with the
function matherr(3M).
Page 2 May 1989