1 #include <math.h> 2 #include <stdint.h> 3 copysignf(float x,float y)4 float copysignf(float x, float y) 5 { 6 union {float f; uint32_t i;} ux={x}, uy={y}; 7 ux.i &= 0x7fffffff; 8 ux.i |= uy.i & 0x80000000; 9 return ux.f; 10 } 11