eqnp

A simple symbolic derivative calculator and simplification engine.

Goal

The goal of eqnp is to be a program which can parse expressions (and maybe equations at some point) and can manipulate them in various ways. This might eventually include:

• Simplifying
• Differentiating (finding derivatives)
• Integrating (finding integrals)
• Solving (isolating variables)

In addition, this is a project that I'm creating only from my own knowledge. My goal is to not use any resources relating to the actual function of eqnp. (Python documentation is acceptable, of course.)

Install

eqnp is a Python package, so it can be installed in multiple ways.

Install directly from repository

Run the following command to download and install eqnp.

$ python -m pip install git+https://github.com/kdkasad/eqnp

Clone repository

Another method is to clone the repository first, then install from the local copy.

$ git clone https://github.com/kdkasad/eqnp
$ cd eqnp
$ python -m pip install .

Usage

Import the parse_expression() function from eqnp.parser:

from eqnp.parser import parse_expression

# or

from eqnp import *

Then run parse_expression(...), passing in a string which is an expression. See below for syntax.

Example

In [1]: import eqnp

In [2]: function = eqnp.parse_expression(' 1 / x^2 ')

In [3]: print(function)
Out[3]: Division(1, Exponent(x, 2))

In [4]: derivative = function.differentiate(respectTo='x')

In [5]: print(derivative)
Out[5]: Division(Subtraction(Multiplication(0, Exponent(x, 2)), Multiplication(1, Multiplication(Multiplication(2, Exponent(x, Subtraction(2, 1))), 1))), Exponent(Exponent(x, 2), 2))

In [6]: derivative = derivative.simplify_fully()

In [7]: print(derivative)
Out[7]: Division(Subtraction(0, Multiplication(2, x)), Exponent(x, 4))

      # Out[7] is equivalent to '(-2 * x) / (x ^ 4)'

Expression string syntax

Currently, the following operators, functions, and other syntactical structures are supported (... means an expression):

Syntax	Meaning
... + ...	Addition -- Must have operands on either side
... - ...	Subtraction -- Must have operands on either side
... * ...	Multiplication -- Must have operands on either side
... / ...	Division -- Must have operands on either side
(...)	Grouping -- used to group operations to enforce a certain order
|...|	Absolute value -- same as abs(...)
abs(...)	Absolute value
sin(...)	Sine function
cos(...)	Cosine function
tan(...)	Tangent function
csc(...)	Cosecant function
sec(...)	Secant function
cot(...)	Cotangent function
-n	Negation -- n must be a constant number

Note: The absolute value bars do not have to be escaped. They're only that way in the markdown file because the table syntax uses pipe characters.

To do

There are still a lot of features that I want to implement. Some are listed as # TODO: comments in the source code, but I'll put a list here too:

• Pull all constants out of nested multiplication expressions
• Flip negative exponents in fractions to opposite side
• Add inverse trigonometric functions
• Implement integration