Math.Log10() Method in C#

The Math.Log10() method in C# calculates the base-10 logarithm of a specified number. This method is particularly useful in mathematical calculations, scientific computations, and when working with exponential data that needs to be converted to a logarithmic scale.

Syntax

Following is the syntax for the Math.Log10() method −

public static double Log10(double d);

Parameters

d − A double-precision floating-point number whose base-10 logarithm is to be found.

Return Value

The Log10() method returns different values based on the input parameter −

Using Math.Log10() with Special Values

The following example demonstrates how Math.Log10() handles special floating-point values −

using System;

public class Demo {
    public static void Main() {
        double val1 = Double.PositiveInfinity;
        double val2 = Double.NegativeInfinity;
        double val3 = Double.NaN;
        
        Console.WriteLine("Log10(PositiveInfinity) = " + Math.Log10(val1));
        Console.WriteLine("Log10(NegativeInfinity) = " + Math.Log10(val2));
        Console.WriteLine("Log10(NaN) = " + Math.Log10(val3));
    }
}

The output of the above code is −

Log10(PositiveInfinity) = Infinity
Log10(NegativeInfinity) = NaN
Log10(NaN) = NaN

Using Math.Log10() with Regular Numbers

This example shows the behavior of Math.Log10() with common numerical values −

using System;

public class Demo {
    public static void Main() {
        double val1 = 0;
        double val2 = 1;
        double val3 = 10;
        double val4 = 100;
        double val5 = -5;
        
        Console.WriteLine("Log10(0) = " + Math.Log10(val1));
        Console.WriteLine("Log10(1) = " + Math.Log10(val2));
        Console.WriteLine("Log10(10) = " + Math.Log10(val3));
        Console.WriteLine("Log10(100) = " + Math.Log10(val4));
        Console.WriteLine("Log10(-5) = " + Math.Log10(val5));
    }
}

The output of the above code is −

Log10(0) = -Infinity
Log10(1) = 0
Log10(10) = 1
Log10(100) = 2
Log10(-5) = NaN

Practical Application Example

Here's a practical example that demonstrates using Math.Log10() to calculate the number of digits in an integer −

using System;

public class Demo {
    public static void Main() {
        int[] numbers = {12, 345, 6789, 12345};
        
        Console.WriteLine("Number\tDigits");
        Console.WriteLine("---------------");
        
        foreach (int num in numbers) {
            int digits = (int)Math.Floor(Math.Log10(num)) + 1;
            Console.WriteLine(num + "\t" + digits);
        }
    }
}

The output of the above code is −

Number	Digits
---------------
12	2
345	3
6789	4
12345	5

Conclusion

The Math.Log10() method is essential for calculating base-10 logarithms in C#. It handles special cases like zero, negative numbers, and infinity appropriately, making it reliable for mathematical computations and scientific applications where logarithmic calculations are required.