HP 40gs - Manual (Page 268)

15-16 Equation Writer
Press to obtain an
intermediate result, (4– 2)(4
+ 2), and
again to
evaluate the intermediate
result. The final answer, as
before, is 12.
N o t e If you call a CAS function while you’re writing an
expression, whatever is currently selected is copied to the
function’s first or main argument. If nothing is selected,
the cursor is placed at the appropriate location for
completing the arguments.
Equation Writer variables
You can store objects in variables, then access an object
by using the name of its variable. However, you should
note the following:
• Variables used in CAS cannot be used in HOME, and
vice versa.
• In HOME or in the program editor, use to store
an object in a variable.
• In CAS, use the STORE command (on the
menu) to store a value in a variable.
• The key displays a menu that contains all the
available variables. Pressing while you are in
HOME displays the names of the variables defined in
HOME and in the Aplets. Pressing
while you
are in the Equation Writer displays the names of the
variables defined in CAS (as explained on
page 15-18).
Predefined CAS variables
• VX contains the name of the current symbolic
variable. Generally, this is X, so you should not use X
as the name of a numeric variable. Nor should you
erase the contents of X with the
UNASSIGN command
(on the menu) after having done a symbolic
calculation.
• EPS contains the value of epsilon used in the EPSX0
command.
hp40g+.book Page 16 Friday, December 9, 2005 1:03 AM