/sys$common/syshlp/helplib.hlb CC, Run-time functions, frexp  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Calculates the fractional and exponent parts of a double value.
  The fractional part is returned as the return value; the exponent
  is placed in the integer variable pointed to by eptr.

  Syntax:

       #include <math.h>

       double frexp(double value, int *eptr);