C MathLog Examples

In this tutorial, we will learn about the C# Math.Log() method, and learn how to use this method to the natural logarithm of a number or logarithm of a number in specified base, with the help of examples.

LogDouble d

Math.Log(d) returns the natural (base e) logarithm of a specified number d.

Syntax

The syntax of Log() method is 

Math.Log(Double d)

where

Parameter Description
d The double value whose natural logarithm is to be found.

Return Value

The method returns a value of type double.

Example 1 Logd

In this example, we will find the natural logarithm of the following values.

  • Positive Value
  • Negative Value
  • Positive Infinity
  • Negative Infinity
  • Zero

C# Program

using System;

class Example {
    static void Main(string[] args) {
        Double d, result;

        d = 8;
        result = Math.Log(d);
        Console.WriteLine($"Log({d}) = {result}");

        d = -7;
        result = Math.Log(d);
        Console.WriteLine($"Log({d}) = {result}");

        d = Double.PositiveInfinity;
        result = Math.Log(d);
        Console.WriteLine($"Log({d}) = {result}");

        d = Double.NegativeInfinity;
        result = Math.Log(d);
        Console.WriteLine($"Log({d}) = {result}");

        d = 0;
        result = Math.Log(d);
        Console.WriteLine($"Log({d}) = {result}");
    }
}

Output

Log(8) = 2.07944154167984
Log(-7) = NaN
Log(∞) = ∞
Log(-∞) = NaN
Log(0) = -∞

LogDouble d, Double newBase

Math.Log(d, newBase) returns the logarithm of a specified number d in a specified base newBase.

Syntax

The syntax of Log() method is 

Math.Log(Double a, Double newBase)

where

Parameter Description
a The double value whose logarithm is to be found.
newBase The base of the logarithm.

Return Value

The method returns a value of type double.

Example 2 Logd, newBase

In this example, we will find the logarithm of the following values.

  • Positive Value to Base 3
  • Negative Value to Base 3
  • 3 to the Base 3
  • Negative Infinity to Base 3
  • Zero to Base 3

C# Program

using System;

class Example {
    static void Main(string[] args) {
        Double d, newBase, result;

        d = 9;
        newBase = 3;
        result = Math.Log(d, newBase);
        Console.WriteLine($"Log({d}) to the base {newBase} = {result}");

        d = -7;
        newBase = 3;
        result = Math.Log(d, newBase);
        Console.WriteLine($"Log({d}) to the base {newBase} = {result}");

        d = 3;
        newBase = 3;
        result = Math.Log(d, newBase);
        Console.WriteLine($"Log({d}) to the base {newBase} = {result}");

        d = Double.NegativeInfinity;
        newBase = 3;
        result = Math.Log(d, newBase);
        Console.WriteLine($"Log({d}) to the base {newBase} = {result}");

        d = 0;
        newBase = 3;
        result = Math.Log(d, newBase);
        Console.WriteLine($"Log({d}) to the base {newBase} = {result}");
    }
}

Output

Log(9) to the base 3 = 2
Log(-7) to the base 3 = NaN
Log(3) to the base 3 = 1
Log(-∞) to the base 3 = NaN
Log(0) to the base 3 = -∞

Conclusion

In this C# Tutorial, we have learnt the syntax of C# Math.Log() method, and also learnt how to use this method with the help of examples.