This repository contains a PyQt5 based program to aid in visualizing taking limits in obtaining the derivative of a function. It is meant to supplement a quick tour of derivatives.
If your Linux (-compatible) environment does not have PyQt5 support,
install it with the appropriate command, e.g., apt install python3-qtpy for systems that use the apt package manager.
The program visualize.py displays two graphs by default, one for
f(x) and the other for f'(x) over a range x0 to x1. The function f
and the range boundaries x0 and x1 are command-line arguments (via
--min-x and --max-x). Beneath the two graphs are sliders, one for
x and the other for Δx, where Δx is used in the numerical derivative
f'(x).
To run it, you can specify the function to be plotted using the -f
command line flag. It takes a string as an argument, which is
evaluated as python code. The default function is math.sin.
By default, the numerical derivative is computed by using the slope
between the points (x, f(x)), and (x+Δx, f(x+Δx)), or the "plus"
approximation. The --approximation-method switch can be used to
specify other approximations.
The -D flag specifies the number of derivative graphs (minium 1) to
display. I wouldn't recommend too many if you want to be able to play
with the sliders, since it will probably be too slow.
Different functions you might try:
$ ./visualize.py -f 'lambda x: x**3' -D 2
$ ./visualize.py -f 'lambda x: math.sin(x)*math.cos(10*x)'
There is help for all the flags, so try ./visualize.py --help and
experiment!