IRR Calculation in TM1 9.5

[Goatship]

Dear All,

I have a series of cash flow against a Year dimension (randomly negative and positive values, no pattern at all, but always at least one negative and one positive). I would like to calculate IRR.
I have learned that TM1 web can do it in Excel, but we only use the TM1 Contributor, any idea on how to write rule for IRR ? or
Any finance website you suggest I go ask finance people about the IRR formula ?


IRR = Internal Rate of Return, same as an effective interest rate, I believe.
For more information on IRR:
http://en.wikipedia.org/wiki/Internal_rate_of_return

Thank you.