frexp

       integral components

SYNOPSIS
       #include <math.h>

       double frexp(double x, int *exp);
       float frexpf(float x, int *exp);
       long double frexpl(long double x, int *exp);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       frexpf(), frexpl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

DESCRIPTION
       The  frexp()  function  is used to split the number x into a normalized
       fraction and an exponent which is stored in exp.

RETURN VALUE
       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  (exclu-
       sive), that is, [0.5,1).

       If  x  is zero, then the normalized fraction is zero and zero is stored
       in exp.

       If x is a NaN, a NaN is returned, and the value of *exp is unspecified.

       If x is positive infinity (negative infinity), positive infinity (nega-
       tive infinity) is returned, and the value of *exp is unspecified.

ERRORS
       No errors occur.

CONFORMING TO
       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
       4.3BSD, C89.

EXAMPLE
       The program below 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

   Program source

       #include <math.h>

           printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",
                  x, r, r, FLT_RADIX, exp, x);
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       ldexp(3), modf(3)

COLOPHON
       This page is part of release 3.35 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://man7.org/linux/man-pages/.



                                  2010-09-20                          FREXP(3)
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