package com.gunshi.project.xyt.util;

import org.apache.commons.math3.distribution.GammaDistribution;

import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;

/**
 * @author cxw
 * @description
 * @classname BigdecimalUtil.java
 * @create 2024-11-06, 星期三, 10:33:41
 */
public class BigdecimalUtil {


    /**
     * @description: 小数指数计算
     * @param base 底数
     * @param exponent 指数
     * @return: java.math.BigDecimal
     * @auther: cxw
     * @date: 2024-11-06, 周三, 10:34:47
     */
    public static BigDecimal bigDecimalExponentiation(BigDecimal base, double exponent) {
        BigDecimal result = BigDecimal.valueOf(Math.pow(base.doubleValue(), exponent)).round(new MathContext(10, RoundingMode.HALF_UP));
        return result;
    }


    /**
     * @description: 计算x的伽马函数
     * @param x
     * @return: java.math.BigDecimal
     * @auther: cxw
     * @date: 2024-11-06, 周三, 11:31:24
     */
    public static double gammaDist(double x, double alpha, double beta, boolean cumulative) {
        GammaDistribution gammaDist = new GammaDistribution(alpha, 1/beta);
        if (cumulative) {
            return gammaDist.cumulativeProbability(x);
        } else {
            return gammaDist.density(x);
        }
    }
}