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fpclassify (3)
  • fpclassify (3) ( Solaris man: Библиотечные вызовы )
  • fpclassify (3) ( FreeBSD man: Библиотечные вызовы )
  • fpclassify (3) ( Русские man: Библиотечные вызовы )
  • >> fpclassify (3) ( Linux man: Библиотечные вызовы )
  • fpclassify (3) ( POSIX man: Библиотечные вызовы )
  •  

    NAME

    fpclassify, isfinite, isnormal, isnan, isinf - floating-point
    classification macros
     
    

    SYNOPSIS

    #include <math.h>
    
    int fpclassify(x);
    
    int isfinite(x);
    
    int isnormal(x);
    
    int isnan(x);
    
    int isinf(x);
    

    Link with -lm.

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

    fpclassify(), isfinite(), isnormal(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
    isnan(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE; or cc -std=c99
    isinf(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99  

    DESCRIPTION

    Floating point numbers can have special values, such as infinite or NaN. With the macro fpclassify(x) you can find out what type x is. The macro takes any floating-point expression as argument. The result is one of the following values:
    FP_NAN
    x is "Not a Number".
    FP_INFINITE
    x is either positive infinity or negative infinity.
    FP_ZERO
    x is zero.
    FP_SUBNORMAL
    x is too small to be represented in normalized format.
    FP_NORMAL
    if nothing of the above is correct then it must be a normal floating-point number.

    The other macros provide a short answer to some standard questions.

    isfinite(x)
    returns a non-zero value if
    (fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
    isnormal(x)
    returns a non-zero value if (fpclassify(x) == FP_NORMAL)
    isnan(x)
    returns a non-zero value if (fpclassify(x) == FP_NAN)
    isinf(x)
    returns 1 if x is positive infinity, and -1 if x is negative infinity.
     

    CONFORMING TO

    C99, POSIX.1.

    For isinf(), the standards merely say that the return value is non-zero if and only if the argument has an infinite value.  

    NOTES

    In glibc 2.01 and earlier, isinf() returns a non-zero value (actually: 1) if x is positive infinity or negative infinity. (This is all that C99 requires.)  

    SEE ALSO

    finite(3), INFINITY(3), isgreater(3), signbit(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
    CONFORMING TO
    NOTES
    SEE ALSO
    COLOPHON


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