37 lines
1.3 KiB
Java
37 lines
1.3 KiB
Java
import java.math.BigDecimal;
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import java.math.MathContext;
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import java.util.Objects;
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public class Calculate_Pi {
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private static final MathContext con1024 = new MathContext(1024);
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private static final BigDecimal bigTwo = new BigDecimal(2);
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private static final BigDecimal bigFour = new BigDecimal(4);
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private static BigDecimal bigSqrt(BigDecimal bd, MathContext con) {
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BigDecimal x0 = BigDecimal.ZERO;
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BigDecimal x1 = BigDecimal.valueOf(Math.sqrt(bd.doubleValue()));
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while (!Objects.equals(x0, x1)) {
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x0 = x1;
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x1 = bd.divide(x0, con).add(x0).divide(bigTwo, con);
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}
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return x1;
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}
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public static void main(String[] args) {
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BigDecimal a = BigDecimal.ONE;
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BigDecimal g = a.divide(bigSqrt(bigTwo, con1024), con1024);
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BigDecimal t;
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BigDecimal sum = BigDecimal.ZERO;
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BigDecimal pow = bigTwo;
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while (!Objects.equals(a, g)) {
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t = a.add(g).divide(bigTwo, con1024);
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g = bigSqrt(a.multiply(g), con1024);
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a = t;
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pow = pow.multiply(bigTwo);
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sum = sum.add(a.multiply(a).subtract(g.multiply(g)).multiply(pow));
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}
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BigDecimal pi = bigFour.multiply(a.multiply(a)).divide(BigDecimal.ONE.subtract(sum), con1024);
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System.out.println(pi);
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}
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}
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