Finding Derivatives - HP 39gs User Manual

Symbolic
calculations in
the Function
aplet

Finding derivatives

To find derivatives
in HOME
Using mathematical functions
(The | symbol is in the CHARS menu: press
The = sign is listed in the MATH menu under Symbolic
functions.)
You can perform symbolic operations in the Function
aplet's Symbolic view. For example, to find the derivative
of a function in the Function aplet's Symbolic view, you
define two functions and define the second function as a
derivative of the first function. You then evaluate the
second function. See "To find derivatives in the Function
aplet's Symbolic view" on page 13-22 for an example.
The HP 39gs can perform symbolic differentiation on
some functions. There are two ways of using the HP 39gs
to find derivatives.
•
You can perform differentiations in HOME by using
the formal variables, S1 to S5.
•
You can perform differentiations of functions of X in
the Function aplet.
To find the derivative of the function in HOME, use a
formal variable in place of X. If you use X, the
differentiation function substitutes the value that X holds,
and returns a numeric result.
For example, consider the function:
2
( x ( )
dx sin + 2 cos
1. Enter the differentiation function onto the command
line, substituting S1 in place of X.
2
x ( ) )
S1
S1
.
CHARS
13-21