Java Java.math.BigInteger.modInverse()用法及代碼示例

modPow()方法返回此模m的模乘逆。如果m> = 0或沒有乘法逆模m(即gcd(this，m)!= 1)，則此方法引發ArithmeticException。

用法:

public BigInteger modInverse(BigInteger m)

參數：m-模數。

返回值：該方法返回一個BigInteger對象，其值為((this)^(-1)mod m)。

異常：

ArithmeticException-m> = 0，或者此BigInteger不具有乘法逆模m(即，此BigInteger相對於m而言不是素數)。

以下示例程序旨在說明BigInteger.modInverse()方法：

程序1:：

import java.math.*; 
import java.util.Scanner; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        Scanner sc = new Scanner(System.in); 
  
        // create 2 BigInteger objects 
        BigInteger biginteger1, biginteger2, result; 
  
        // Initialize all BigInteger Objects 
        biginteger1 = new BigInteger("8"); 
        biginteger2 = new BigInteger("21"); 
  
        // perform modInverse operation on biginteger1 using biginteger2. 
        result = biginteger1.modInverse(biginteger2); 
  
        String expression = biginteger1 + " ^ -1 % "
                            + biginteger2 + " = " + result; 
  
        // print result value 
        System.out.println(expression); 
    } 
}

輸出：

8 ^ -1 % 21 = 8

程序2:

import java.math.*; 
import java.util.Scanner; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        Scanner sc = new Scanner(System.in); 
  
        // create 2 BigInteger objects 
        BigInteger biginteger1, biginteger2, result; 
  
        // Initialize all BigInteger Objects 
        biginteger1 = new BigInteger(88882); 
        biginteger2 = new BigInteger(22224); 
  
        // perform modInverse operation on biginteger1 using biginteger2. 
        result = biginteger1.modInverse(biginteger2); 
  
        String expression = biginteger1 + " ^ -1 % "
                            + biginteger2 + " = " + result; 
  
        // print result value 
        System.out.println(expression); 
    } 
}

輸出：

Exception in thread "main" java.lang.ArithmeticException: BigInteger not invertible.
    at java.math.MutableBigInteger.modInverse(Unknown Source)
    at java.math.MutableBigInteger.mutableModInverse(Unknown Source)
    at java.math.BigInteger.modInverse(Unknown Source)
    at BigInteger.GFG2.main(GFG2.java:23)

參考： https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#modInverse(java.math.BigInteger)

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注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 Java.math.BigInteger.modInverse() method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。