SIGNBIT(3) Linux Programmers Manual SIGNBIT(3)
signbit - test sign of a real floating point number
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
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 sign
bit(-0.0) will return a non-zero value.
C99. This function is defined in IEC 559 (and the appendix with recom
mended functions in IEEE 754/IEEE 854).
This page is part of release 3.05 of the Linux man-pages project. A
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be found at http://www.kernel.org/doc/man-pages/.
GNU 2002-08-10 SIGNBIT(3)