5 min before class and I have to post this else the day will sweep it through.
14 March (=3.14 in the US) is known as the π (3.14159) Day
To celebrate this very special day I am posting a Monte-Carlo method to calculate Pi.
Here is the link to the method a seen on Academo.org
You can try the code yourself in javascript:
var demo = new Demo({
ui: {
addOne: {
title: “Add points one-by-one”,
type: “button”
},
animate: {
title: “Animate”,
value: false,
},
speed: {
title: “Speed”,
value: 1,
range: [5, 100],
resolution: 1,
input: “hidden”,
},
reset: {
title: “Reset”,
type: “button”
},
},
animateID: null,
totalPoints: 0,
innerPoints: 0,
radius: 250,
init: function(){
$(‘<canvas>’).attr({
id: “my-canvas”,
height: “500px”,
width: “500px”,
}).css({
width: “100%”,
“max-width”: “500px”,
“max-height”: “500px”,
“height”: “100%”,
“margin”: “0 auto”,
“display”: “block”,
“border”: “solid 1px #CCC”
}).appendTo(‘#demo’);
this.scale = d3.scale.linear()
.domain([-1, 1])
.range([0, 500]);
this.canvas = document.getElementById(“my-canvas”);
this.context = this.canvas.getContext(“2d”);
this.initCanvas();
$(“#ui-container”).prepend(“
“);
$(“#js-points-data”).append(“Total Number of points: <span class=’js-total-points’>0</span><br />”);
$(“#js-points-data”).append(“Points within circle: <span class=’js-inner-points’>0</span><br />”);
$(“#js-points-data”).append(“Pi estimation: <span class=’js-pi-estimation’></span><br />”);
},
initCanvas: function(){
this.context.clearRect(0,0,500,500);
this.context.strokeStyle = “#999”;
this.context.beginPath();
this.context.arc(this.scale(0), this.scale(0), this.radius, 0, 2 * Math.PI);
this.context.stroke();
},
animate: function(){
this.animateID = window.requestAnimationFrame(this.animate.bind(this));
this.update();
},
reset: function(){
this.totalPoints = 0;
this.innerPoints = 0;
this.updateDisplay();
},
updateDisplay: function(){
$(“.js-inner-points”).html(this.innerPoints);
$(“.js-total-points”).html(this.totalPoints);
var piEstimate = (4 * this.innerPoints / this.totalPoints).toFixed(5);
if (this.totalPoints == 0){
piEstimate = “”;
}
$(“.js-pi-estimation”).html(piEstimate);
},
update: function(e){
if (e == “speed”){
} else if (e == “animate” && this.ui.animate.value == true) {
this.animate();
} else if (e == “animate” && this.ui.animate.value == false) {
window.cancelAnimationFrame(this.animateID);
} else if (e == “reset”) {
this.initCanvas();
this.reset();
} else {
if (e == “addOne”){
var numberToAdd = 1;
} else {
var numberToAdd = this.ui.speed.value;
}
for (var i = 0 ; i < numberToAdd ; i++){
var randomX = Math.random() * 2 – 1;
var randomY = Math.random() * 2 – 1;
this.context.beginPath();
if (Math.pow(this.scale(randomX) – this.scale(0), 2) + Math.pow(this.scale(randomY) – this.scale(0), 2) > Math.pow(this.radius, 2)){
this.context.fillStyle = “blue”;
} else {
this.context.fillStyle = “red”;
this.innerPoints++;
}
this.context.fillRect(this.scale(randomX),this.scale(randomY),1,1);
this.totalPoints++;
this.updateDisplay();
}
}
}
});
Have a real Haπ Day!
An Isotopia 