A formula for IRR

[salvomic]

(05-18-2015 09:20 AM)akmon Wrote:  Anyway I made two little changes:

fsolve(ΣLIST(MAKELIST((L1(I)/X^(I-1)),I,1,SIZE(L1))),X)-1

Example: L1= {-123400, 36200, 54800, 48100}

TIR = 0,0596, or 5,96%
...
I tried your example, Salvomic, and it nails it: 0,1306 or 13,06%.

this formula is quite good, but with another example of 12C I've troubles using it in the program:
{-79000, 14000, 11000, 10000, 10000, 10000, 9100, 9000, 4500, 100000}
12C gives IRR 13.72% (0.1372), Prime "Error: bad argument value" with the program...
With the formula directly I've two solution:
[-101369... 0.13719...], obviously only the second result is ok (positive)...

So, why then in the program it doesn't work?

Instead, with this code

Code:


EXPORT IRR()
// Thanks Cyrille, Akmon, Dale, salvomic
BEGIN
EDITLIST(flows);
irr2();
END;

#cas
irr2():=
BEGIN
fsolve(ΣLIST(MAKELIST((flows(I)/X^(I-1)),I,1,SIZE(flows))),X)-1;
END;
#end

the program works better with the new list (with 2 results), but always the output is a ugly
program({},{},[0.1306288...])
I'm searching to avoid the "program(..." part