HP 39g+, User Manual

Page: 164 / 294

11-20 Using mathematical functions
SEC
Secant: 1/cos x .
SEC
( value )
Symbolic calculations
The hp 39g+ has the ability to perform symbolic
calculations, for example, symbolic integration and
differentiation. You can perform symbolic calculations in
HOME and in the Function aplet.
In HOME
When you perform calculations that contain normal
variables, the calculator substitutes values for any
variables. For example, if you enter A+B on the command
line and press
, the calculator retrieves the values
for A and B from memory and substitutes them in the
calculation.
Using formal
variables
To perform symbolic calculations, for example symbolic
differentiations and integrations, you need to use formal
names. The hp 39g+ has six formal names available for
use in symbolic calculations. These are S0 to S5. When
you perform a calculation that contains a formal name,
the hp 39g+ does not carry out any substitutions.
You can mix formal names and real variables. Evaluating
(A+B+S1)
2
will evaluate
A+B
, but not
S1
.
If you need to evaluate an expression that contains formal
names numerically, you use the | (
where ) command,
listed in the Math menu under the Symbolic category.
For example to evaluate
(S1*S2)
2
when
S1=2
and
S2=4
, you would enter the calculation as follows:
(The | symbol is in the CHARS menu: press
CHARS
.
The = sign is listed in the MATH menu under Symbolic
functions.)