使用对数函数

找出两个数的差

原文:https://www . geesforgeks . org/find-两个数差-使用-log-function/

给定两个整数 a 和 b ，任务是使用日志功能找到 a 和 b 的减法，即 (a-b) 。

注意:我们不能使用–运算符。

示例:

输入: a = 4，b = 81 输出: -77

输入: a = -3，b = 16 输出: -19

输入: a = -3，b =-13 T3】输出: 10

方法:要编写此问题的解决方案，请使用日志的以下三个属性

• 对数(a/b)=对数(a)–对数(b)
• log _a (a)= 1
• 原木(a ^b )= b 原木(a)

结合这三个属性，写。

log_e(e^a/e^b) =>log_e(e^a)–log_e(e^b){使用属性 1 } =>log_e(e)–blog_e(e){使用属性 2 }>

注:T2 e 为欧拉数即 2.71828

按照以下步骤解决问题:

• a-b 的减法将对数(exp(a) / exp(b)) 作为答案。

下面是上述方法的实现。

C++

// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;

// Function to find the subtraction
// of two number a and b i.e, (a-b)
int subtract(int a, int b)
{
    return log(exp(a) / exp(b));
}

// Driver Code
int main()
{
    int a = -15;
    int b = 7;

    cout << subtract(a, b);

    return 0;
}

Java 语言(一种计算机语言，尤用于创建网站)

// Java program for the above approach
class GFG {

    // Function to find the subtraction
    // of two number a and b i.e, (a-b)
    static int subtract(int a, int b) {
        return (int) Math.log(Math.exp(a) / Math.exp(b));
    }

    // Driver Code
    public static void main(String[] args) {
        int a = -15;
        int b = 7;

        System.out.print(subtract(a, b));

    }
}

// This code is contributed by shikhasingrajput

Python 3

# Python3 program for the above approach
import math

# Function to find the subtraction
# of two number a and b i.e, (a-b)
def subtract(a, b) :
    return math.log(math.exp(a) / math.exp(b));

# Driver Code
if __name__ == "__main__" :

    a = -15;
    b = 7;

    print(subtract(a, b));

    # This code is contributed by AnkThon

C

// C# program for the above approach
using System;

public class GFG {

    // Function to find the subtraction
    // of two number a and b i.e, (a-b)
    static int subtract(int a, int b)
    {
        return (int)Math.Log(Math.Exp(a) / Math.Exp(b));
    }

    // Driver Code
    public static void Main(string[] args) {
        int a = -15;
        int b = 7;

        Console.Write(subtract(a, b));
    }
}

// This code is contributed by AnkThon

java 描述语言

<script>
        // JavaScript Program to implement
        // the above approach

        // Function to find the subtraction
        // of two number a and b i.e, (a-b)
        function subtract(a, b) {
            return Math.log(Math.exp(a) / Math.exp(b));
        }

        // Driver Code

        let a = -15;
        let b = 7;

        document.write(subtract(a, b));

    // This code is contributed by Potta Lokesh
    </script>

Output

-22

时间复杂度:O(1) T5辅助空间:** O(1)

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