TRIG(3M)                             SysV                             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 [-pi/2,pi/2].

     acos returns the arccosine of x, in the range [0,pi].

     atan returns the arctangent of x, in the range [-pi/2,pi/2].

     atan2 returns the arctangent of y/x, in the range (-pi,pi], using the
     signs of both arguments to determine the quadrant of the return value.

SEE ALSO
     matherr(3M).

DIAGNOSTICS
     For sin, cos, and tan, if x is NaN, either errno is set to indicate the
     error or NaN is returned.

     These functions 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, and
     only if you have linked your program to /usr/lib/crt0.o, 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, if you have linked your program to /usr/lib/crt0.o, a

     message indicating DOMAIN error is printed on the standard error output.
     For atan, if x is NaN, NaN is returned.  Otherwise, either errno is set
     to indicate the error or NaN is returned.

     These error-handling procedures may be changed with the function
     matherr(3M).

ERRORS
     sin, cos, or tan fails if the following is true:

     [ERANGE]       The magnitude of x is such that total or partial loss of
                    significance resulted.

     asin, and acos, fail if the following is true:

     [EDOM]         The x parameter is not in the domain [-1,1].

     atan2 fails if the following is true:

     [EDOM]         Both arguments are zero or one of the arguments is NaN.