HP C/iX Library Reference Manual (30026-90004)

Chapter 5 177
HP C/iX Library Function Descriptions
frexp
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 *2
n
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;
printf("%g = %g * 2^%d\n", value, x, eptr);
}
See Also
ldexp(), modf(), ANSI C 4.5.4.2, POSIX.1 8.1