SymPy basics

SymPy is the Python symbolic calculus library on which the package relies. Below are some basics about the possibilities it offers. For more information, refer to SymPy’s doc.

Symbols and functions

To declare a parameter \(t\) and a function \(f(t)\) using SymPy, run:

from sympy import symbols, Function
t = symbols("t")
f = Function("f")(t)

Working with expressions

Combinations of symbols and/or Functions form SymPy expressions. For instance,

expr = 2*f*t

is an expression. Expressions can be simplified, developed or factored using the .simplify(), .expand(), .factor() methods.

One can also collect specific terms in a (developed) expression using

dic = expr.collect(term, evaluate=False)

This returns a dictionary whose keys are powers of term and values are the factor of these keys in expr.

Display

The lines

from sympy.physics.vector.printing import init_vprinting
init_vprinting(use_latex=True, forecolor='White') # Initialise latex printing

allow to initialise the output display such that

• LaTeX is used for rendering if the python environment supports it.

• The LaTeX colour is set to white (ideal for dark modes)

Additionally, one can display the unformatted LaTeX expression (for copy-paste in a LaTeX document for instance) using

from sympy.physics.vector.printing import vlatex
print(vlatex(expr))