Created
April 15, 2015 14:56
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<!DOCTYPE html> | |
<html lang="ja"> | |
<head> | |
<script> | |
function rungekutta(n,xn,f0,f1,x0,y00,y10) { | |
var h = (xn - x0) / n; | |
var xi = x0, obj = [y00,y10]; | |
function step(x,obj) { | |
var y0 = obj[0], y1 = obj[1]; | |
var k01 = h*f0(x, y0, y1), | |
k11 = h*f1(x, y0, y1), | |
k02 = h*f0(x+h/2, y0+k01/2, y1+k11/2), | |
k12 = h*f1(x+h/2, y0+k01/2, y1+k11/2), | |
k03 = h*f0(x+h/2, y0+k02/2, y1+k12/2), | |
k13 = h*f1(x+h/2, y0+k02/2, y1+k12/2), | |
k04 = h*f0(x+h, y0+k03, y1+k13), | |
k14 = h*f1(x+h, y0+k03, y1+k13); | |
obj[0] += (k01+2*k02+2*k03+k04)/6; | |
obj[1] += (k11+2*k12+2*k13+k14)/6; | |
} | |
for (var i = 0; i < n; xi = x0 + h*++i) { | |
step(xi,obj); | |
} | |
return obj; | |
} | |
function solve() { | |
var elem0 = document.getElementById("result0"), | |
elem1 = document.getElementById("result1"), | |
n = document.getElementById("precision").value, | |
x = document.getElementById("x").value, | |
f0str = document.getElementById("function0").value, | |
f1str = document.getElementById("function1").value, | |
x0 = document.getElementById("x0").value, | |
y00 = document.getElementById("y00").value, | |
y10 = document.getElementById("y10").value; | |
var f0 = new Function("x","y0","y1",f0str), | |
f1 = new Function("x","y0","y1",f1str); | |
var res = rungekutta(+n, +x, f0, f1, +x0, +y00, +y10); | |
elem0.value = res[0]; | |
elem1.value = res[1]; | |
} | |
var dict = { | |
// hoge: { xn: , f0: , f1: , x0: , y00: , y10: } | |
nothing: {}, | |
cos1: { xn: 1, f0: "return y1", f1: "return -y0", x0: 0, y00: 1, y10: 0 }, | |
second: { f0: "return y1", f1: "/* y0''(x,y0,y0') */" } | |
} | |
window.onload = function () { | |
var ex = document.getElementById("examples"); | |
for (var i in dict) { | |
var opt = document.createElement("option"); | |
opt.value = i; opt.textContent = i; | |
ex.appendChild(opt); | |
} | |
} | |
function selectExample(ev) { | |
var ex = dict[ev.target.value]; | |
document.getElementById("x").value = ex.xn || null; | |
document.getElementById("function0").value = ex.f0 || null; | |
document.getElementById("function1").value = ex.f1 || null; | |
document.getElementById("x0").value = ex.x0 || null; | |
document.getElementById("y00").value = ex.y00 || null; | |
document.getElementById("y10").value = ex.y10 || null; | |
} | |
</script> | |
</head> | |
<body> | |
<p>precision is <input id="precision" value="100"></input></p> | |
<p>dy0/dx = <input id="function0"></input></p> | |
<p>dy1/dx = <input id="function1"></input></p> | |
<p>y0(<input id="x0"></input>) | |
= <input id="y00"></input></p> | |
<p>y1( ) | |
= <input id="y10"></input></p> | |
<button onclick="solve()">Solve</button> | |
<p>y0(<input id="x"></input>) | |
= <input type="text" id="result0" size="25" readonly></input></p> | |
<p>y1( ) | |
= <input type="text" id="result1" size="25" readonly></input></p> | |
<p> | |
you can choose example: | |
<select id="examples" onchange="selectExample(event)"> | |
</select> | |
</p> | |
</body> | |
</html> |
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