Created
March 20, 2017 02:35
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JavaScriptとCanvasでモンテカルロ法で円周率を求める
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <meta http-equiv="X-UA-Compatible" content="ie=edge"> | |
| <title>モンテカルロ法</title> | |
| <style> | |
| canvas { | |
| width :200px; | |
| height:200px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas id="mycanvas" width="200" height="200"></canvas> | |
| <div>π=<span id="piValue">0.0</span></div> | |
| <script src="1.5.1.montecalro.js"></script> | |
| </body> | |
| </html> |
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| "use strict"; | |
| let inCount = 0; | |
| let counter = 0; | |
| const piValue = document.getElementById('piValue'); | |
| function loop(canvas) { | |
| counter++; | |
| window.requestAnimationFrame(()=>{ loop(canvas)}); | |
| const ctx = canvas.getContext('2d'); | |
| const scale = canvas.width; | |
| const x = Math.random(1); | |
| const y = Math.random(1); | |
| if (x * x + y * y < 1) { | |
| ctx.strokeStyle = 'rgb(255,0,0)'; | |
| inCount++; | |
| } else { | |
| ctx.strokeStyle = 'rgb(0, 255,0)'; | |
| } | |
| ctx.strokeRect(x * scale, y * scale, 1, 1); | |
| piValue.innerHTML = (4*inCount) / counter; | |
| } | |
| loop(document.getElementById('mycanvas')); |
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