### The Noisy Sine Map

```// Forked from "The Sine Map" by mdiamond
// https://turtletoy.net/turtle/b8ae13c558

const scale = 65;
const iterations =25000;

/*
Try changing the value of k
and the start coordinate
*/

const k = 3;
const start = [1, 1];

setup();
const turtle = getTurtle();
const scale_noise = 38.2; // min=0, max=100, step=.1

// const wrinkles = 7; // min=0, max=10, step=.1

const noise  = new SimplexNoise(69);

let posclean = start;

function walk(i) {
[posclean, posdirty]= iterate(posclean)
turtle.setpos(posdirty);
return i < iterations;
}

function iterate([x, y]) {
[x, y] = [x / scale, y / scale];
let no = noise.noise2D([x, y]);
let clean= [
Math.sin(k * (y + x)) * scale,
Math.sin(k * (y - x)) * scale
];
let dirty= [
Math.sin(k * (y + x)) * scale,
Math.sin(k * (y - x)) * scale
];
dirty[0]=dirty[0] + no*scale_noise;
dirty[1]=dirty[1] + no*scale_noise;
// xn= wrinkleNoise([x, y]);
// dirty[0]=dirty[0] + xn*scale_noise;
// dirty[1]=dirty[1] + xn*scale_noise;
return [clean, dirty]
}

function getTurtle () {
const turtle = new Turtle();
turtle.penup();
turtle.goto(start);
turtle.pendown();
return turtle;
}

function setup() {
Canvas.setpenopacity(0.2);
}

function wrinkleNoise(x, y) {
let n = noise.noise2D([x, y]);
return Math.sin(n * 3. * wrinkles) * ((.5 + .5 *n)**2);
}
////////////////////////////////////////////////////////////////
// Simplex Noise utility code. Created by Reinder Nijhoff 2020
// https://turtletoy.net/turtle/6e4e06d42e
// Based on: http://webstaff.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
////////////////////////////////////////////////////////////////
function SimplexNoise(seed = 1) {
const grad = [  [1, 1, 0], [-1, 1, 0], [1, -1, 0], [-1, -1, 0],
[1, 0, 1], [-1, 0, 1], [1, 0, -1], [-1, 0, -1],
[0, 1, 1], [0, -1, 1], [0, 1, -1], [0, -1, -1] ];
const perm = new Uint8Array(512);

const F2 = (Math.sqrt(3) - 1) / 2, F3 = 1/3;
const G2 = (3 - Math.sqrt(3)) / 6, G3 = 1/6;

const dot2 = (a, b) => a[0] * b[0] + a[1] * b[1];
const sub2 = (a, b) => [a[0] - b[0], a[1] - b[1]];
const dot3 = (a, b) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
const sub3 = (a, b) => [a[0] - b[0], a[1] - b[1], a[2] - b[2]];

class SimplexNoise {
constructor(seed = 1) {
for (let i = 0; i < 512; i++) {
perm[i] = i & 255;
}
for (let i = 0; i < 255; i++) {
const r = (seed = this.hash(i+seed)) % (256 - i)  + i;
const swp = perm[i];
perm[i + 256] = perm[i] = perm[r];
perm[r + 256] = perm[r] = swp;
}
}
noise2D(p) {
const s = dot2(p, [F2, F2]);
const c = [Math.floor(p[0] + s), Math.floor(p[1] + s)];
const i = c[0] & 255, j = c[1] & 255;
const t = dot2(c, [G2, G2]);

const p0 = sub2(p, sub2(c, [t, t]));
const o  = p0[0] > p0[1] ? [1, 0] : [0, 1];
const p1 = sub2(sub2(p0, o), [-G2, -G2]);
const p2 = sub2(p0, [1-2*G2, 1-2*G2]);

let n =  Math.max(0, 0.5-dot2(p0, p0))**4 * dot2(grad[perm[i+perm[j]] % 12], p0);
n += Math.max(0, 0.5-dot2(p1, p1))**4 * dot2(grad[perm[i+o[0]+perm[j+o[1]]] % 12], p1);
n += Math.max(0, 0.5-dot2(p2, p2))**4 * dot2(grad[perm[i+1+perm[j+1]] % 12], p2);

return 70 * n;
}
hash(i) {
i = 1103515245 * ((i >> 1) ^ i);
const h32 = 1103515245 * (i ^ (i>>3));
return h32 ^ (h32 >> 16);
}
}
return new SimplexNoise(seed);
}```