frexp, frexpf, frexpl — convert floating-point number to fractional and integral components
#include <math.h>
double frexp( |
double | x, |
int * | exp) ; |
float
frexpf( |
float | x, |
int * | exp) ; |
long
double frexpl( |
long double | x, |
int * | exp) ; |
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Note |
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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 its absolute value 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
.
#include <math.h> #include <float.h> #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { double x, r; int exp; x = strtod(argv[1], NULL); r = frexp(x, &exp); printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n", x, r, r, FLT_RADIX, exp, x); exit(EXIT_SUCCESS); } /* main */
This program produces results such as the following:
$ ./a.out 2560 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 $ ./a.out −4 frexp(−4, &e) = −0.5: −0.5 * 2^3 = -4
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