golang fast float rounding

fast_float_round.go

// https://www.h-schmidt.net/FloatConverter/IEEE754.html
// simplest rounding is just removing right bits from mantisa
func fastFloatRound(f float32) float32 {
	fbits := math.Float32bits(f)
	fbits = fbits >> 15
	fbits = fbits << 15
	fRounded := math.Float32frombits(fbits)
	return fRounded
}

fast_float_round_test.go

func Test_fastFloatRound(t *testing.T) {
	assert.Equal(t, float32(10.09375), fastFloatRound(10.1234567))
	assert.Equal(t, float32(99840), fastFloatRound(99999.123456789))
	assert.Equal(t, float32(3.3961775e+38), fastFloatRound(math.MaxFloat32))
}