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frexp, frexpf, frexpl - convert floating-point number to fractional and integral components

#include<math.h>doublefrexp(doublex,int*exp);floatfrexpf(floatx,int*exp);longdoublefrexpl(longdoublex,int*exp);Link with-lm. Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):frexpf(),frexpl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; orcc-std=c99

Thefrexp() function is used to split the numberxinto a normalized fraction and an exponent which is stored inexp.

Thefrexp() function returns the normalized fraction. If the argumentxis not zero, the normalized fraction isxtimes a power of two, and its absolute value is always in the range 1/2 (inclusive) to 1 (exclusive), that is, [0.5,1). Ifxis zero, then the normalized fraction is zero and zero is stored inexp. Ifxis a NaN, a NaN is returned, and the value of*expis unspecified. Ifxis positive infinity (negative infinity), positive infinity (negative infinity) is returned, and the value of*expis unspecified.

No errors occur.

C99, POSIX.1-2001. The variant returningdoublealso conforms to SVr4, 4.3BSD, C89.

The program below produces results such as the following: $./a.out2560frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 $./a.out-4frexp(-4, &e) = -0.5: -0.5 * 2^3 = -4Programsource#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 */

ldexp(3),modf(3)

This page is part of release 3.24 of the Linuxman-pagesproject. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. 2008-10-29