Brownian motion.

public/main.js

@@ -36,6 +36,12 @@ var touch_identifier
 var moving_origin = []
 var moving_epsilon = 0.04
 
+// brownian motion constants
+var brownian_callback = false
+var brownian_eps = 0.1
+var brownian_time = 50
+var brownian_time_elapsed = 0
+
 function p_to_canv_coords(x, y) {
 	return [p_canvas.width * (x + p_scale) / (2 * p_scale), p_canvas.height * (-y + p_scale) / (2 * p_scale)]
 }
@@ -244,7 +250,21 @@ function zoom_out_dr() {
 	update_zoom()
 }
 
+function clear_matrix() {
+	brownian_time_elapsed = 0
+
+	matrix_entries = []
+	for (let i = 0; i < 2 * dim * dim; i++) {
+		matrix_entries[i] = 0
+	}
+
+	p_draw()
+	dr_draw()
+}
+
 function randomize_matrix() {
+	brownian_time_elapsed = 0
+
 	matrix_entries = []
 	for (let i = 0; i < dim * dim; i++) {
 		matrix_entries.push((6.0 * Math.random()) - 3.0)
@@ -302,6 +322,8 @@ function enter_matrix() {
 			}
 		}
 
+		brownian_time_elapsed = 0
+
 		matrix_entries = entries
 		make_grid()
 		p_draw()
@@ -310,6 +332,8 @@ function enter_matrix() {
 }
 
 function dim_update() {
+	brownian_time_elapsed = 0
+
 	var old_dim = dim
 	dim = Number(document.getElementById("dim").value)
 	update_dr_scale()
@@ -356,6 +380,8 @@ function dim_update() {
 var input_timers = {};
 
 function input_update(e) {
+	brownian_time_elapsed = 0
+
 	const input = e.srcElement;
 	const row = input.dataset.row;
 	const col = input.dataset.col;
@@ -546,3 +572,58 @@ function mouse_up(e) {
 		mouse_moving = false
 	}
 }
+
+function brownian_checkbox() {
+	if (document.getElementById('brownian').checked) {
+		brownian_time_elapsed = 0
+		brownian_callback = window.setInterval(brownian_motion, brownian_time)
+		document.getElementById('brownian_modifiers').style.display = 'block'
+	} else {
+		window.clearInterval(brownian_callback)
+		document.getElementById('brownian_modifiers').style.display = 'none'
+	}
+}
+
+function brownian_freq_update() {
+	f = document.getElementById('brownian_freq').value
+	if (f < 10) f = 10
+	if (f > 10000) f = 10000
+	document.getElementById('brownian_freq').value = f
+
+	if (document.getElementById('brownian').checked) {
+		window.clearInterval(brownian_callback)
+		brownian_callback = window.setInterval(brownian_motion, brownian_time)
+	}
+}
+
+function brownian_eps_update() {
+	e = document.getElementById('brownian_eps').value
+	if (e <= 0) e = 0
+	if (e > 6) e = 6
+	document.getElementById('brownian_eps').value = e
+	brownian_eps = e
+}
+
+function brownian_motion() {
+	brownian_time_elapsed += brownian_time
+
+	entries = matrix_entries
+	for (let i = 0; i < 2 * dim * dim; i++) {
+		entries[i] += brownian_eps * Math.sqrt(0.0001 * brownian_time_elapsed) * gaussian_random()
+		if (-3 > entries[i]) entries[i] = -3;
+		if (entries[i] > 3) entries[i] = 3;
+	}
+
+	matrix_entries = entries
+	make_grid()
+	p_draw()
+	dr_draw()
+}
+
+// https://stackoverflow.com/a/36481059
+function gaussian_random(mean = 0, stdev = 0.5) {
+    const u = 1 - Math.random();
+    const v = Math.random();
+    const z = Math.sqrt( -2.0 * Math.log( u ) ) * Math.cos( 2.0 * Math.PI * v );
+    return z * stdev + mean;
+}

public/tjsm.html

@@ -48,6 +48,7 @@ canvas {
 
 
 <button id="enhance" type="button" onclick="enhance()" disabled>enhance</button>
+<button id="clear_button" type="button" onclick="clear_matrix()">clear</button>
 <button id="randomize_button" type="button" onclick="randomize_matrix()">randomize</button>
 <button id="zoom_in_button" type="button" onclick="zoom_in_dr()">+</button>
 <button id="zoom_out_button" type="button" onclick="zoom_out_dr()">-</button>
@@ -58,6 +59,14 @@ canvas {
 
 <br>
 
+<input type="checkbox" id="brownian" onclick="brownian_checkbox()">Brownian motion</input>
+<div id="brownian_modifiers" style="display:none">
+update time = <input type="number" id="brownian_freq" onChange="brownian_freq_update()" value="50" min="10" max="10000" style="width: 100px;"> ms <br>
+speed = <input type="number" id="brownian_eps" onChange="brownian_eps_update()" value="0.1" min="0" max="6" style="width: 100px;">
+</div>
+
+<br>
+
 <a href="https://arxiv.org/abs/2310.03227">paper</a> by
 <a href="https://web.math.princeton.edu/~oeh">Otte Hein&#228;vaara</a>.
 <a href="https://ahti.space/git/shikhin/tjsm">source</a>.