FREXP(3) Linux Programmer's Manual FREXP(3)
frexp - convert floating-point number to fractional and integral compo-
double frexp(double x, int *exp);
The frexp() function is used to split the number x into a normalized
fraction and an exponent which is stored in exp.
The frexp() function returns the normalized fraction. If the argument
x is not zero, the normalized fraction is x times a power of two, and
is always in the range 1/2 (inclusive) to 1 (exclusive). If x is zero,
then the normalized fraction is zero and zero is stored in exp.
SVID 3, POSIX, BSD 4.3, ISO 9899
GNU 1993-06-06 FREXP(3)