HP HP-15C Advanced Functions Handbook

Section 2: Working With [J[\9
the actual behavior of the process or event, you would not be
justified in using the calculated value to the full apparent accuracy.
Round-Off Error in Internal Calculations
With any computational device—including the HP-15C—calcu-
lated results must be "rounded off to a finite number of digits (10
digits in the HP-15C). Because of this round-off error, calculated
results—especially results of evaluating a function that contains
several mathematical operations—may not be accurate to all 10
digits that can be displayed. Note that round-off error affects the
evaluation of any mathematical expression, not just the evaluation
of a function to be integrated using f7T|. (Refer to the appendix for
additional information.)
If f(x) is a function relating to a physical situation, its inaccuracy
due to round-off typically is insignificant compared to the
inaccuracy due to empirical constants, etc. If f(x) is what we have
called a pure mathematical function, its accuracy is limited only by
round-off error. Generally, it would require a complicated analysis
to determine precisely how many digits of a calculated function
might be affected by round-off. In practice, its effects are typically
(and adequately) determined through experience rather than
analysis.
In certain situations, round-off error can cause peculiar results,
particularly if you should compare the results of calculating
integrals that are equivalent mathematically but differ by a
transformation of variables. However, you are unlikely to
encounter such situations in typical applications.
Shortening Calculation Time
The time required for [W\o calculate an integral depends on how
soon a certain density of sample points is achieved in the region
where the function is interesting. The calculation of the integral of
any function will be prolonged if the interval of integration
includes mostly regions where the function is not interesting.
Fortunately, if you must calculate such an integral, you can modify
the problem so that the calculation time is reduced. Two such
techniques are subdividing the interval of integration and
transformation of variables.

HP HP-15C Specifications

General

Brand	HP
Model	HP-15C
Category	Calculator
Language	English