Math.Sqrt

This function takes the square root of a number. With it, you pass one Double value as an argument, and receive the square root of that as another Double.

This function requires more time to compute fractional square roots. We can use caching to speed up square roots.

This program takes the square roots of 4 Doubles and prints them with Console.WriteLine. We can see that the square root of 1 is 1, and the square root of four is two.

Module Module1
    Sub Main()
        Dim result1 As Double = Math.Sqrt(1)
        Dim result2 As Double = Math.Sqrt(2)
        Dim result3 As Double = Math.Sqrt(3)
        Dim result4 As Double = Math.Sqrt(4)

        Console.WriteLine(result1)
        Console.WriteLine(result2)
        Console.WriteLine(result3)
        Console.WriteLine(result4)
    End Sub
End Module
1
1.4142135623731
1.73205080756888
2

Performance

Let's look into the performance of Math.Sqrt. Some arguments to Math.Sqrt are much faster than others—the performance depends on what arguments are used.

Module Module1
        Sub Main()
        Dim m As Integer = 10000000
        Dim s1 As Stopwatch = Stopwatch.StartNew
        For i As Integer = 0 To m - 1
            If Math.Sqrt(4) = 1 Then
                Throw New Exception
            End If
        Next
        s1.Stop()

        Dim s2 As Stopwatch = Stopwatch.StartNew
        For i As Integer = 0 To m - 1
            If Math.Sqrt(4.1) = 1 Then
                Throw New Exception
            End If
        Next
        s2.Stop()

        Dim u As Integer = 1000000
        Console.WriteLine(((s1.Elapsed.TotalMilliseconds * u) / m).ToString("0.00 ns"))
        Console.WriteLine(((s2.Elapsed.TotalMilliseconds * u) / m).ToString("0.00 ns"))
    End Sub
End Module
2.61 ns
6.20 ns

We examined several aspects of Math.Sqrt. And we investigated its performance—its arguments affect the time it requires to compute a result.