21 lines
515 B
Text
21 lines
515 B
Text
func runge_kutta(yp) {
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func (t, y, δt) {
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var a = (δt * yp(t, y));
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var b = (δt * yp(t + δt/2, y + a/2));
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var c = (δt * yp(t + δt/2, y + b/2));
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var d = (δt * yp(t + δt, y + c));
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(a + 2*(b + c) + d) / 6;
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}
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}
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define δt = 0.1;
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var δy = runge_kutta(func(t, y) { t * y.sqrt });
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var(t, y) = (0, 1);
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loop {
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t.is_int &&
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printf("y(%2d) = %12f ± %e\n", t, y, abs(y - ((t**2 + 4)**2 / 16)));
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t <= 10 || break;
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y += δy(t, y, δt);
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t += δt;
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}
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