signbit

signbit - test sign of a real floating point number

#include <math.h> I int signbit( X ); Compile with -std=c99; link with -lm.

`signbit' is a generic macro which can work on all real floating-point types. It returns a non-zero 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 non-zero value.

C99. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).

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