Lissajous figures: 2nd Order from gopl

lissajous.go

package main
import (
	"os"
	"image"
	"image/color"
	"image/gif"
	"io"
	"math"
	"math/rand" //Todo: PRNG
)

//Global variables donot use :=
var colPalette = []color.Color{color.White, color.Black}

const(
	whiteVal = 0 // = because constants cannot use :=
	blackVal = 1
)

func main() {
	lissajousWaveGen(os.Stdout)
}

func lissajousWaveGen(out io.Writer) {
	const(
		TF_Order = 2
		angularRes = 0.001
		frameSize = 100 // +-100 overall
		animFrames = 64
		delay = 8 // 80ms
	)
	frequency := rand.Float64() * 3.0 //Go's PRNG
	animation := gif.GIF{LoopCount:animFrames} //LoopCount is inside GIF type struct
	// LoopCount 0 = Looping unconditional
	// Loop count -1 = Show frame once, then done!

	phaseDiff := 0.00
	for i := 0; i < animFrames; i++ {
		rectangleFrame := image.Rect(0,0, 2*frameSize + 1, 2*frameSize + 1)
		img := image.NewPaletted(rectangleFrame,colPalette)

		for phi := 0.0; phi < (TF_Order * 2 * math.Pi); phi += angularRes {
			x := math.Sin(phi)
			y := math.Sin(phi * frequency + phaseDiff)

			img.SetColorIndex(frameSize + int(x * frameSize + 0.5), frameSize + int(y * frameSize + 0.5), blackVal)
			// Dont use float for mapping, easier computation but at a cost of accuracy. Hence the conversion!!
			// Last parameter = baseIndex
		}
		phaseDiff += 0.01
		animation.Delay = append(animation.Delay, delay)
		animation.Image = append(animation.Image, img)
	}
	gif.EncodeAll(out, &animation) //Not acquanited with references yet
}

There appears a small constriction in one of the constructive points between two waves. Maybe due to use of integer math.
Also, not sure if 2nd order wave is to start from the top of the bottom. I don't AKS's notes right now