A formula for IRR

[DrD]

Here's a twist on the theme, requires NO pre-definition, but will work with the list, if it is predefined:

Code:


EXPORT IRR()
BEGIN
  // test vals: {-123400, 36200, 54800, 48100} 
  IFTE(size(L1)==0,input({L1}),break); // purists will HATE this, some feel its wrong usage of this function!
  return fsolve(ΣLIST(MAKELIST((L1(I)/X^(I-1)),I,1,SIZE(L1))),X)-1; //  (Original command line from Akmon)      
END;

You would need to clear the input line if you input a brace enclosed set of values, of course.

* Feel free to change the IFTE(), to: if size(L1)==0 then input({L1}); end; ... for those so inclined!

There is an issue with IFTE() vs. the IF THEN ELSE END conditional block. I don't know the author's original design intention, but I see IFTE() as a convenient short hand for the other IF construct (in some cases). It has been attempted to explain that IFTE() is not intended to process a command as a T/F clause verb, only to process a value. It does process some commands, but reports syntax error on others. Stuff for another thread, perhaps ...