Microsoft.VisualBasic.Financial.IRR - Error in C#

[smlemmon]

Hi,

This is my first post, but have been an avid reader up until to now. Great resource though.

Anyway, onto my problem.

I need to use the Microsoft.VisualBasic.Financial.IRR procedure in my C# / ASP.NET 2.0 application.

The code I am using is shown below:-

Decimal monthlyROI = 0;
Decimal ROI = 0;
Double estimate = 0.1;
Double[] irrArray;
ArrayList irrArrayList = new ArrayList();
 
irrArrayList.Add((Double)Decimal.Negate(amountOfCredit));
 
for (int termLoop = 0; termLoop < (term - 2); termLoop++)
{
     irrArrayList.Add((Double)standardFinancePayment);
}
 
 irrArrayList.Add((Double)Decimal.Add(monthlyFinancePayment, finalPayment));
 
irrArray = (Double[])irrArrayList.ToArray(typeof(Double));
 
monthlyROI = (Decimal)Microsoft.VisualBasic.Financial.IRR(ref irrArray, estimate);
 
ROI = Decimal.Multiply(monthlyROI, 12);
 
return ROI;

When I run this peice of code, the call to Microsoft.VisualBasic.Financial.IRR raises an exception, "Arguments Are Not Valid".

I thought it might have been to do with using the array list, and then populating the array with the contents of it.

I tried just using a standard Double Array and then assigning its size when it was instantiated. THis too didnt work.

The only way I can get this function to work correctly is by instantiating the array with values at design time as follows:-

Double[] irrArray = {-22500.00, 770, 770, 600, 500, 7770, 666,555,444,666,666};

I am sure I am missing something really simple here and any guidance would be really appreciated.

Regards

Simon