Golang least squares method

least_squares_method.go

package main

import "fmt"

type Point struct {
	x float64
	y float64
}

func LeastSquaresMethod(points *[]Point) (a float64, b float64){
	// http://ja.wikipedia.org/wiki/%E6%9C%80%E5%B0%8F%E4%BA%8C%E4%B9%97%E6%B3%95

	n := float64(len(*points))

	sumX := 0.0
	sumY := 0.0
	sumXY := 0.0
	sumXX := 0.0

	for _, p := range *points{
		sumX += p.x
		sumY += p.y
		sumXY += p.x * p.y
		sumXX += p.x * p.x
	}

	base :=  (n * sumXX - sumX * sumX)
	a = (n * sumXY - sumX * sumY) / base
	b = (sumXX * sumY - sumXY * sumX) / base

	return a, b
}

func main() {
	points := make([]Point, 0)

	points = append(points, Point{x:0.0, y:1.0,})
	points = append(points, Point{x:0.1, y:1.5,})
	points = append(points, Point{x:0.2, y:2.0,})
	points = append(points, Point{x:0.3, y:2.5,})
	points = append(points, Point{x:0.4, y:3.0,})
	points = append(points, Point{x:0.5, y:3.5,})
	points = append(points, Point{x:0.6, y:4.0,})

	a, b := LeastSquaresMethod(&points)
	fmt.Println(a)
	fmt.Println(b)
}