HP 10B - Manual (Page 130)

B
More About Calculations
IRR/YR Calculations
The calculator determines IRR/YR for a set of cash flows using
mathematical formulas that “search” for the answer. The process finds a
solution by estimating an answer and then using that estimate to do
another calculation —this is called an iterative process.
In most cases, the calculator finds the desired answer, since there is usu­
ally only one solution to the calculation. However, calculating IRR/YR for
certain sets of cash flows is more complex. There may be more than one
(or no) mathematical solution to the problem. In these cases, the calcula­
tor displays a message to help you interpret what has happened.
Possible Outcomes of Calculating IRR/YR
These arc the possible outcomes of an IRR/YR calculation:
■ Case 1.
The calculator displays a positive answer. This is the only
positive answer. However, one or more negative answers may exist.
■ Case
2. The calculator finds a negative answer but a single positive
answer also exists. It displays; POS Irr ALSO. To sec the negative
answer, press 0 to clear the message. To search for the positive
answer, you must input a gucs.s. (Refer to “nnicring a Guess for
IRR/YR/* below). There might also be additional negative answers.
■ Case
3. The calculator displays a negative answer and no message.
This is the only answer.
■ Case 4.
The calculator displays the message: Error - Soln. This
indicates that the calculation is very complex. It might involve more
than one positive or negative answer, or there may be no solution. To
continue the calculation, you must store a guess (see below).
B: Moro About Calculations 127