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

UPDATE: almost all of the points below have been taken care of, all that remains is to add mathematically complete definitions for vector spaces and algebras to section 6.1 and 6.2 in the tutorial.

Suggested fixes for "GAP -- A Tutorial Release 4.11.0, 29-Feb-2020"

On page 41, in the first sentence after the first Example

Pretty-print GATs as LaTeX in both of the following styles:

1. Cartmell-style linear notation

2. natural-deduction-style tree notation
   <img width="680" alt="image" src="https://user-images.githubusercontent.com/316610/91097121-f953b080-e613-11ea-8dda-8da598

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#L1834

• 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.