COPYSIGN(3) Library Functions Manual COPYSIGN(3)
copysign, copysignf, copysignl -- functions to manipulate signs
Math Library (libm, -lm)
copysign(double x, double y);
copysignf(float x, float y);
copysignl(long double x, long double y);
The copysign(), copysignf(), and copysignl() functions return a value
whose absolute value matches x, but whose sign bit is taken from y.
Upon successful completion, all three functions return a value with the
magnitude of x and the sign of y. If x is NaN , the functions return a
NaN with the sign of y.
The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').
Note that on implementations that represent a signed zero but do not
treat negative zero consistently in arithmetic operations, these
functions may regard the sign of zero as positive.
NetBSD 6.1.5 April 13, 2011 NetBSD 6.1.5