HP 50g Graphing Calculator - Manual (Page 55)

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_Last Stack: Keeps the contents of the last stack entry for use with the functions
UNDO and ANS (see Chapter 2).
The _Beep option can be useful to advise the user about errors. You may want
to deselect this option if using your calculator in a classroom or library.
The _Key Click option can be useful as an audible way to check that each
keystroke was entered as intended.
The _Last Stack option is very useful to recover the last operation in case we
need it for a new calculation.
To select, or deselect, any of these three options, first press the H button.
Next,
Θ Use the down arrow key, ˜, four times to select the _Last Stack option.
Use the @ @CHK@@ soft menu key to change the selection.
Θ Press the left arrow key š to select the _Key Click option. Use the @ @CHK@@
soft menu key to change the selection.
Θ Press the left arrow key š to select the _Beep option. Use the @ @CHK@@ soft
menu key to change the selection.
Press the !!@@OK#@ soft menu key to complete the operation.
Selecting CAS settings
CAS stands for Computer Algebraic System. This is the mathematical core of
the calculator where the symbolic mathematical operations and functions are
programmed and performed. The CAS offers a number of settings can be
adjusted according to the type of operation of interest. These are:
Θ The default independent variable
Θ Numeric vs. symbolic mode
Θ Approximate vs. Exact mode
Θ Verbose vs. Non-verbose mode
Θ Step-by-step mode for operations
Θ Increasing power format for polynomials
Θ Rigorous mode
Θ Simplification of non-rational expressions
Details on the selection of CAS settings are presented in Appendix C.