HP HP-15C, Руководство пользователя

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Section 13: Finding the Roots of an Equation 193
Restriction on the Use of
_
The one restriction regarding the use of
_
is that
_
cannot be
used recursively. That is, you cannot use
_
in a subroutine that is
called during the execution of
_
. If this situation occurs, execution
stops and
Error 7
is displayed. It is possible, however, to use
_
with
f
thereby using the advanced capabilities of both of these keys.
Memory Requirements
_
requires five registers to operate. (Appendix C explains how they
are automatically allocated from memory.) If five unoccupied registers are
not available,
_
will not run and Error 10 will be displayed.
A routine that combines
_
and
f
requires 23 registers of space.
For Further Information
In appendix D, Advanced Use of
_
, additional techniques and
explanations for using
_
are presented. These include:

How
_
works.

Accuracy of the root.

Interpreting results.

Finding several roots.

Limiting estimation time.