signbit — test sign of a real floating point number
#include <math.h>
int
            signbit( | 
            x); | 
          
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            Note | 
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               Compile with   | 
          
signbit() is a generic macro
      which can work on all real floating-point types. It returns a
      nonzero value if the value of x has its sign bit set.
This is not the same as x <
      0.0, because IEEE 754 floating point allows zero
      to be signed. The comparison -0.0
      < 0.0 is false, but signbit(−0.0) will
      return a nonzero value.
C99. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
This page is part of release 2.79 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/.
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                 Copyright 2002 Walter Harms (walter.harmsinformatik.uni-oldenburg.de) Distributed under GPL Based on glibc infopages  |