HP HP-18C - Appendix B: more about HP-18 C Calculations; IRR% Calculations

More About HP-18C
Calculations
IRRO/o Calculations
B
The HP-18C calculates IRR% for a set of cash flows using mathemati-
cal formulas that "search" for the answe r. The process finds a solution
by estimating an answer and then using that estimate to do another
calculation-in mathematical terms, an iterative process.
In
most cases, the HP -18C finds the correct answer, since there is
usually only
one solution to the calculation. However, calculating
IRR% for certain sets
of cash flows is more comp l ex. There may be
more than one mathematical solution to the problem , or there may be
no solution . In these cases, the HP-18C displays a message to help
you interpret what has happened.
Possible Outcomes of Calculating IRR%
These are the possible outcomes of an IRR% calculation for which
you have not stored a guess. Storing a guess is covered on page 170 .
• Case 1: The HP-18C displays a positive answer . This is the only
positive answer. However,
one or more negative answers may exist.
• Case 2: The HP-18C displays a negative answer and the message:
IRR%>0 EXISTS; TO SEEK :
INPUT GUESS
[STO]{IRR%}
The HP -18C has detected that there is a single positive answer. To
search for that positive answer, you must input a guess. (Refer to
Storing a Guess for IRR% on page 170). There may also be one or
more additional negative answers .
B: More About HP-18C Calculations 169