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frexpf (3)
  • frexpf (3) ( FreeBSD man: Библиотечные вызовы )
  • >> frexpf (3) ( Linux man: Библиотечные вызовы )
  • frexpf (3) ( POSIX man: Библиотечные вызовы )
  •  

    NAME

    frexp, frexpf, frexpl - convert floating-point number to fractional
    and 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; 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 (exclusive), 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 (negative 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>
    #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 */
    
     

    SEE ALSO

    ldexp(3), modf(3)  

    COLOPHON

    This page is part of release 3.14 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    RETURN VALUE
    ERRORS
    CONFORMING TO
    EXAMPLE
    Program source
    SEE ALSO
    COLOPHON


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