Float Comparison Benchmark: Subtraction vs Multiplication

floatcomp_test.go

package main

import (
	"math"
	"math/rand"
	"runtime"
	"testing"
)

const DELTA_MULT = 10000000000
const DELTA_SUB = 0.00000001

func init() {
	runtime.GOMAXPROCS(1)
}

func compareMult(a float64, b float64, delta float64) bool {
	return int64(a*delta) == int64(b*delta)
}

func compareSub(a float64, b float64, delta float64) bool {
	return math.Abs(a-b) < delta
}

func BenchmarkMultiplication(b *testing.B) {
	float1 := rand.Float64()
	float2 := rand.Float64()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		compareMult(float1, float2, DELTA_MULT)
	}
}

func BenchmarkSubtraction(b *testing.B) {
	float1 := rand.Float64()
	float2 := rand.Float64()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		compareSub(float1, float2, DELTA_SUB)
	}
}

Results on a 2014 MacBook Pro with a 2.6 GHz Core i5:

$ go test -bench .
testing: warning: no tests to run
PASS
BenchmarkMultiplication 2000000000           1.36 ns/op
BenchmarkSubtraction    500000000            5.55 ns/op