Press to view the calculus menu, then to select numerical differentiation, nDer.

The syntax is: `nDer( `

*expression*`,`

*variable*
[`,`

*value*]` )`

The numerical derivative option approximates the first derivative
of *expression* with respect to *variable* at *value*.
If *value* is omitted, the current value of *variable* is used.

The value of can be changed in the tolerance editor available by pressing . typically has a value of about 0.0001.

Though this method is less accurate than der1, it can be used to evaluate any expression, including a single nesting of itself for calculating the second derivative.