f64 f64_inv(f64 f) { if (F64_IS_ZERO(f)) return F64_NAN; return s64_to_f64( ((int64_t)0x7fffffffffffffff) / (f64_to_s64(f)/2) ); }
f64 f64_neg(f64 f) { return s64_to_f64( -f64_to_s64(f) ); }
f64 f64_sub(f64 a, f64 b) { return s64_to_f64( f64_to_s64(a) - f64_to_s64(b) ); }