Double type returns -1.#IND/NaN error when calculating pi iteratively
- by Draak
I am working through a problem for my MCTS certification. The program has to calculate pi until the user presses a key, at which point the thread is aborted, the result returned to the main thread and printed in the console. Simple enough, right? This exercise is really meant to be about threading, but I'm running into another problem. The procedure that calculates pi returns -1.#IND. I've read some of the material on the web about this error, but I'm still not sure how to fix it. When I change double to Decimal type, I unsurprisingly get Overflow Exception very quickly. So, the question is how do I store the numbers correctly? Do I have to create a class to somehow store parts of the number when it gets too big to be contained in a Decimal?
Class PiCalculator
Dim a As Double = 1
Dim b As Double = 1 / Math.Sqrt(2)
Dim t As Double = 1 / 4
Dim p As Double = 1
Dim pi As Double
Dim callback As DelegateResult
Sub New(ByVal _callback As DelegateResult)
callback = _callback
End Sub
Sub Calculate()
Try
Do While True
Dim a1 = (a + b) / 2
Dim b1 = Math.Sqrt(a * b)
Dim t1 = t - p * (a - a1) ^ 2
Dim p1 = 2 * p
a = a1
b = b1
t = t1
p = p1
pi = ((a + b) ^ 2) / (4 * t)
Loop
Catch ex As ThreadAbortException
Finally
callback(pi)
End Try
End Sub
End Class
