243
File name: hp 12c pt_user's guide_English_HDPMF123E27 Page: 243 of 275
Printed Date: 2005/8/1
Dimension: 14.8 cm x 21 cm
Appendix C
More About
L
Given a sequence of positive and negative cash flows, we hope that there is
enough information to determine whether an
IRR
answer exists, and what that
answer is. For the vast majority of cases, your hp 12c platinum will find the unique
IRR
answer if it exists. But the
IRR
computation is so complex that if the cash flow
sequence does not meet certain criteria, then sometimes the calculator is unable to
determine whether or not an answer or answers exist.
Let’s look at all of the possible outcomes of
IRR
as calculated by your hp 12c
platinum:
Case 1:
A positive answer. If a positive answer is displayed, it is the only such
answer. One or more negative answers may also exist.
Case 2:
A negative answer. If a negative answer is displayed, there
may
be
additional negative answers, and there
may
be a single positive answer. If
additional answers (negative or positive) exist, they can be calculated using the
procedure described below.
Case 3:
The calculator displays
Error 3
. This indicates that the computation is
very complex, possibly involving multiple answers, and cannot be continued until
you give the calculator an estimate of
IRR
. The procedure for doing so is described
below.
Case 4:
The calculator displays
Error 7
. This indicates that there is no answer to
the computation of
IRR
with the cash flow amounts you have entered. This situation
is probably the result of a mistake in entering the magnitudes or signs of the cash
flows or the number of times a cash flow amount occurs consecutively. Refer to
Reviewing Cash Flow Entries (page 79) and Changing Cash Flow Entries (page
80) to check and correct the entries.
Error 7
will result if there is not at least one
positive cash flow
and
at least one negative cash flow.
Although the calculator will eventually reach one of the above outcomes, it may
take a long time to get there. You may wish to terminate the
IRR
iterative process,
by pressing any key, to see what interest rate the calculator has computed at that
point. If you stop the calculation, you may continue searching for
IRR
as described
below.