# software for sketching derivatives from arbitrary functions drawn by hand

So, let's say I want to visualize the derivative of an arbitrary function and vice-versa. What software can I use to do this? By arbitrary I mean I just want to draw any function by hand and see the behavior of the derivative. I don't want to introduce an equation to graph its function but to draw the curve by using the pencil thing and the software to show its derivative.

• Geogebra does it from what I remember, but it has the problem that every little hand twitch causes a massive spike and the derivative can be hard to read. – Kaynex Sep 3 '17 at 2:40
• @Kaynex can you show how to do it. I'm sorry I'm so lost – Novato Sep 3 '17 at 2:47
• @Novato On Desmos, you can type $y = \frac{d}{dx} f(x)$. Here is an example illustrating this using a couple of functions. – Toby Mak Sep 3 '17 at 4:18
• Ok.The thing is I don't want to introduce an equation to get the graph of a function but to draw a curve and I from that I want the program to draw the curve of its derivative. – Novato Sep 3 '17 at 5:58
• Define a very step $h$ (for example $h=10^{-4}$) and plot $g$ defined by $g(x):=(f(x+h)-f(x))/h.$ – Jean Marie Sep 3 '17 at 7:06