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#include <math.h> #include <stdint.h> double frexp(double x, int *e) { union { double d; uint64_t i; } y = { x }; int ee = y.i>>52 & 0x7ff; if (!ee) { if (x) { x = frexp(x*0x1p64, e); *e -= 64; } else *e = 0; return x; } else if (ee == 0x7ff) { return x; } *e = ee - 0x3fe; y.i &= 0x800fffffffffffffull; y.i |= 0x3fe0000000000000ull; return y.d; }