52 lines
1.6 KiB
Java
52 lines
1.6 KiB
Java
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package com.gunshi.project.xyt.util;
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import java.math.BigDecimal;
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import java.math.MathContext;
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import java.math.RoundingMode;
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/**
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* @author cxw
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* @description
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* @classname BigdecimalUtil.java
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* @create 2024-11-06, 星期三, 10:33:41
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*/
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public class BigdecimalUtil {
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/**
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* @description: 小数指数计算
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* @param base 底数
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* @param exponent 指数
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* @return: java.math.BigDecimal
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* @auther: cxw
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* @date: 2024-11-06, 周三, 10:34:47
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*/
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public static BigDecimal bigDecimalExponentiation(BigDecimal base, double exponent) {
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BigDecimal result = BigDecimal.valueOf(Math.pow(base.doubleValue(), exponent)).round(new MathContext(10, RoundingMode.HALF_UP));
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return result;
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}
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/**
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* @description: 计算x的伽马函数
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* @param x
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* @return: java.math.BigDecimal
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* @auther: cxw
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* @date: 2024-11-06, 周三, 11:31:24
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*/
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public static BigDecimal bigDecimalGamma(BigDecimal x) {
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BigDecimal result = BigDecimal.valueOf(gamma(x.doubleValue()));
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return result.setScale(x.scale(), RoundingMode.HALF_UP);
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}
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public static double gamma(double x) {
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return Math.exp(logGamma(x));
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}
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public static double logGamma(double x) {
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double tmp = (x - 0.5) * Math.log(x + 4.5) - (x + 4.5);
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double ser = 1.0 + 76.18009173 / (x + 0) - 86.50532033 / (x + 1)
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+ 24.01409822 / (x + 2) - 1.231739516 / (x + 3)
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+ 0.00120858003 / (x + 4) - 0.00000536382 / (x + 5);
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return tmp + Math.log(ser * Math.sqrt(2 * Math.PI));
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}
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}
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