HP 39g+ - Manual (Page 165)

Using mathematical functions 11-21
Symbolic
calculations in the
Function aplet 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 11-22 for an example.
Finding derivatives
The hp 39g+ can perform symbolic differentiation on
some functions. There are two ways of using the hp 39g+
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 derivatives
in HOME 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:
1. Enter the differentiation function onto the command
line, substituting S1 in place of X.
S1
S1
2
S1
2. Evaluate the function.
dx x (
2
) sin ( 2 x ( ) ) cos +