HP 3000 Manuals HP 3000 Manuals
frexp
Breaks a floating-point number into a normalized fraction and an integral
power of 2.
Syntax
#include <math.h>
double frexp (double value, int *eptr);
Parameters
value A real number input to the function.
eptr A pointer to the integer exponent returned by the function.
Return Values
x A real number between 0.5 and 1.
Description
The frexp function accepts a double value, and returns two values, x and
n, such that
value == x * 2n
where x is a double quantity in the range 0.5 < x < 1, and n is an
integer exponent. In the frexp function, value is the value to be
processed, and eptr is a pointer to an integer variable where the
exponent n is to be stored. The quantity x is the return value of frexp.
Example
The following program accepts a number argument and uses frexp to output
that number's representation in the form shown above:
main(argc, argv)
int argc;
char *argv[ ];
{
double value, x, frexp();
int eptr;
sscanf(argv[1], "%lf", &value);
x = frexp(value, &eptr);
printf("%g = %g * 2^%d\n", value, x, eptr);
}
See Also
ldexp(), modf(), ANSI C 4.5.4.2, POSIX.1 8.1