trig(3m)
NAME
sin, cos, tan, asin, acos, atan, atan2 − trigonometric functions
SYNTAX
#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(x, y)
double x, y;
DESCRIPTION
The sin, cos and tan functions return respectively the sine, cosine and tangent of their argument, x, measured in radians.
The asin function returns the arcsine of x, in the range −π/2 to π/2.
The acos function returns the arccosine of x, in the range 0 to π.
The atan function returns the arctangent of x, in the range −π/2 to π/2.
The atan2 function returns the arctangent of y/x, in the range −π to π, using the signs of both arguments to determine the quadrant of the return value.
DIAGNOSTICS
The 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).