GNU/Linux man pages
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GNU/Linux |
CentOS 5.5 |
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signbit(3) |
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signbit − test sign of a real floating point number
#include <math.h>
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).
copysign(3)
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signbit(3) | |