pow(3M)

NAME

     pow - power function

SYNOPSIS

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

     double pow(double x, double y);

DESCRIPTION

     The pow() function computes the value of  x  raised  to  the
     power  y,  x **y .   If  x is negative, y must be an integer
     value.

RETURN VALUES

     Upon successful completion, pow() returns  the  value  of  x
     raised to the power y.

     If x is 0 and y is 0, 1.0 is returned.

     If y is NaN, or y is non-zero and x is NaN, NaN is returned.
     If y is 0.0 and x is NaN, NaN is returned.

     If x is 0.0 and y is negative,  -HUGE_VAL  is  returned  and
     errno may be set to EDOM or ERANGE.

     If the correct value  would  cause  overflow,  _HUGE_VAL  is
     returned, and errno is set to ERANGE.

     If the correct value  would  cause  underflow  to  0,  0  is
     returned and errno may be set to ERANGE.

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

ERRORS

     The pow() function will fail if:

     EDOM  The value of x is negative and y is non-integral.

     ERANGE
           The value to be returned would have caused overflow.

     The pow() function may fail if:

     EDOM  The value of x is 0.0 and y is negative.

     ERANGE
           The correct value would cause underflow.

USAGE

     An application wishing to check for error situations  should
     set errno to 0 before calling pow(). 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

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