25 lines
734 B
Java
25 lines
734 B
Java
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import java.util.function.DoubleFunction;
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public class SimpsonIntegration {
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public static double integrate(DoubleFunction<Double> f, double a, double b) {
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double eps = 1e-10;
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double m = (a + b) / 2;
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double am = simpsonIntegration(f, a, m);
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double mb = simpsonIntegration(f, m, b);
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double ab = simpsonIntegration(f, a, b);
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if (Math.abs(am + mb - ab) < eps)
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return ab;
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return integrate(f, a, m) + integrate(f, m, b);
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}
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static double simpsonIntegration(DoubleFunction<Double> f, double a, double b) {
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return (f.apply(a) + 4 * f.apply((a + b) / 2) + f.apply(b)) * (b - a) / 6;
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}
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// Usage example
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public static void main(String[] args) {
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System.out.println(integrate(x -> Math.sin(x), 0, Math.PI / 2));
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}
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}
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