Calculating a Square Root in Microsoft .Net with Visual Basic
61This tutorial illustrates an adaptation of the Newton method for calculating square roots. Written in Visual Basic and implemented in Visual Basic .Net, this code simply iterates until a reasonably close approximation is calculated.
The square root approximation is governed by the value of the variable epsilon, declared and initialized in line 5.
Function SquareRoot(ByVal x As Double) As Double
Dim g As Double
Dim root As Double
Dim tmp As Double
Const epsilon = 0.00001
'Add some error handling
Try
'Start with a guess in the variable g
g = 2
Do While True ' Infinite Loop. The condition can never become false
'Calculate x / g
tmp = x / g
'Calculate (x/g) squared
tmp = tmp * tmp
'Check to see how close we are to the answer
If System.Math.Abs(tmp - x) <= epsilon Then
Return x / g ' Send the answer back to the calling procedure
End If
'Recalculate the guess
g = ((x / g) + g) / 2
'Start the loop over
Loop
Catch ' Errors end up here
MsgBox("Unable to calculate square root: " & Err.Description, MsgBoxStyle.Critical, "oops")
End Try
End FunctionVisual Basic
Of course, Microsoft has included a square root function in the .Net framework. Our code can be replaced with:
Function SquareRoot(ByVal x As Double) As Double
Return Math.Sqrt(x)
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SimeyC says:
4 months ago
Nice method - long time since I did anything in VB!!!