Consider the following system and its solution:

from sympy import *
from sympy.abc import j,f

# augmented matrix
a=Matrix([
[1,  1, 1,  1, 1,  1, 1,  1,  1],
[0, -1, 0, -1, 0, -1, 0, -1, -j],
[0,  0, 0,  0, 1,  1, 1,  1,  f]
])

x=Matrix(list(linsolve(a))[0])

# check if x is a solution
a[:,:-1]*x-a[:,-1] # should be all 0 but the second term is 'tau0-tau1'

Do you have an

Some code even seems to rely on that.

Might be a good idea to verify all implementations do this (I am aware of only one implementation outside of GAP itself, namely in the io package).

Extend the Graphs module with reflexive graphs (ReflexiveGraph) and symmetric reflexive graphs (SymmetricReflexiveGraph), plus appropriate Graphviz visualization in the GraphvizGraphs module.

improve HarmonicNumber implementation:
https://github.com/axkr/symja_android_library/blob/master/symja_android_library/matheclipse-core/src/main/java/org/matheclipse/core/builtin/Arithmetic.java#L1825

• https://en.wikipedia.org/wiki/Harmonic_number
• https://medium.com/cantors-paradise/the-celebrated-harmonic-numbers-and-how-to-approximate-them-b8747a4efeec

The mark note for algiorithms often looks like this:

apply(note1);
apply(note2);
apply(note3);
...

It would be more convenient to write

apply(note1, note2, note3, ...)

Presumably this just calls atan2 and hypot...

Could also investigate whether upstream Octave can be improved to make these "just work" on any class that has atan2 and hypot.

It could be more informative on pypi.org:

The right column must be expanded to roughly match the left one.