mod.go

package main

import (
	"fmt"
	"math"
	"math/rand"
	"time"
)

func main() {
	n := 100 * 1000
	mod := float64(math.Pi)
	in := make([]float64, 0, n)
	for j := 0; j < n; j++ {
		in = append(in, rand.NormFloat64()) // ExpFloat64, Float64
	}

	out := make([]float64, n)
	t := time.Now()
	NaiveMod(in, out, mod)
	fmt.Println("NaiveMod", time.Since(t))

	out = make([]float64, n)
	t = time.Now()
	MathMod(in, out, mod)
	fmt.Println("MathMod", time.Since(t))
}

func MathMod(in, out []float64, mod float64) {
	for i := range in {
		out[i] = math.Mod(in[i], mod)
	}
}
func NaiveMod(in, out []float64, mod float64) {
	for i := range in {
		out[i] = in[i] - (float64(int64(in[i]/mod)) * mod)
	}
}