In the function below I have a For-Next loop that loops though a range
of cells. Would it be any faster to read the range into an array and
loop through the array?

Function InvDistanceWtd(x, y, xdata as Range, ydata as Range, zdata as
Range, power)
N = Application.Count(xdata)
For i = 1 To N
D = Sqr((x - xdata(i, 1)) ^ 2 + (y - ydata(i, 1)) ^ 2)
SumZoDn = SumZoDn + data(i, 1) / D ^ Power
SumIDn = SumIDn + 1 / D ^ Power
Next i
InvDistanceWtd = SumZoDn / SumIDn
End Function