> I think one point, which isn't brought out here and not well in the
> wikipedia article either, is that given all of the C_t, you still have
> two unknowns: IRR (which we are attempting to solve for) and NPV.
>
> In this case, you want NPV set to zero in order to solve for IRR.  Or
> did I miss something?

Yes.  At least I get the right answer if the "irr" function solves for
NPV=0.  :-)

Paolo