asin(3M)

NAME

     asin - arc sine function

SYNOPSIS

     cc [ flag ... ] file ... -lm [ library ... ]
     #include <math.h>

     double asin(double x);

DESCRIPTION

     The asin() function computes the principal value of the  arc
     sine of x. The value of x should be in the range [-1,1].

RETURN VALUES

     Upon successful completion, asin() returns the arc  sine  of
     x,  in  the range [-pi/2,pi/2] radians. If the value of x is
     not in the range [-1,1] and is not _Inf or NaN,  either  0.0
     or NaN is returned and errno is set to EDOM.

     If x is NaN, NaN is returned.

     If x is _Inf, either 0.0 is returned and  errno  is  set  to
     EDOM or NaN is returned and errno may be set to EDOM.

     For exceptional cases, matherr(3M) tabulates the  values  to
     be returned as dictated by Standards other than XPG4.

ERRORS

     The asin() function will fail if:

     EDOM  The value x is not _Inf or NaN and is not in the range
           [-1,1].

     The asin() function may fail if:

     EDOM  The value of x is _Inf.

USAGE

     An application wishing to check for error situations  should
     set  errno  to  0, then call asin(). If errno is non-zero on
     return, or the return value is NaN, an error has occurred.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     isnan(3M), matherr(3M), sin(3M), attributes(5), standards(5)