Function            frac - round the fractional portion of a real

  Syntax              double frac(double x);

  Prototype in        mathhk.h

  Remarks             frac will return the fractional portion of x.

  Return value        returns the fractional portion of x.

  See also            frac()

  Example             #include <mathhk.h>

                      main()
                      {
                           printf("frac(%lf) = %lf\n",-2.307,
                                  frac(-2.307));

  Program output      frac(-2.307) = -0.307

  Example             see demonum.c