微积分学习笔记（2）：用Go语言画函数图像

使用的Go库

• gonum.org/v1/plot
• image/color

待绘图函数

直接使用三角函$sin$:

func f(x float64) float64 {
	return math.Sin(x)
}

绘图过程

1 创建一个绘图

	p := plot.New()
	assert.NotNil(t, p)
	p.Title.Text = "Function Image"
	p.X.Label.Text = "X"
	p.Y.Label.Text = "Y"

2 生成一些函数的点

	points := make(plotter.XYZs, 100, 100)
	for i := range points {
		x := float64(i) / 10.0
		y := f(x)
		points[i].X = x
		points[i].Y = y
	}

3 将这些点连成线条

	line, err := plotter.NewLine(points)
	assert.Nil(t, err)
	line.Color = color.RGBA{R: 255}
	p.Add(line)

4 将绘图保存到图片

	err = p.Save(4*vg.Inch, 4*vg.Inch, "func_image.png")
	assert.Nil(t, err)

5 绘图效果

完整源码

函数定义

package funcimage

import "math"

func f(x float64) float64 {
	return math.Sin(x)
}

画图像

package funcimage

import (
	"github.com/stretchr/testify/assert"
	"gonum.org/v1/plot"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
	"image/color"
	"testing"
)

func Test_func_image(t *testing.T) {
	p := plot.New()
	assert.NotNil(t, p)
	p.Title.Text = "Function Image"
	p.X.Label.Text = "X"
	p.Y.Label.Text = "Y"

	points := make(plotter.XYZs, 100, 100)
	for i := range points {
		x := float64(i) / 10.0
		y := f(x)
		points[i].X = x
		points[i].Y = y
	}

	line, err := plotter.NewLine(points)
	assert.Nil(t, err)
	line.Color = color.RGBA{R: 255}
	p.Add(line)

	err = p.Save(4*vg.Inch, 4*vg.Inch, "func_image.png")
	assert.Nil(t, err)
}