Remove sparse matrix classes

[purva-thakre]

We want to remove all Sparse matrix classes from functions in toqito and refactor the function to use np.ndarray instead.

Related to #521 (comment). This issue lists functions not listed in #468.

Below is an itemized list of the files that require these changes. If you are interested in working on one of these, comment with which item you want to work on. A maintainer will assign that item to you.

• Remove csr_matrix in toqito/matrices/pauli.py #529
• Remove csr_matrix in toqito/matrices/gell_mann.py #530
• Remove csr_matrix in toqito/states/w_state.py #531
• Remove csr_matrix and dia_matrix in toqito/perms/permute_systems.py #532
• Remove csr_matrix in toqito/matrices/tests/test_gell_mann.py #533
• Remove dia_matrix in toqito/states/max_entangled.py #534
• Remove dia_matrix in toqito/states/max_mixed.py #535
• Remove lil_matrix in toqito/states/ghz.py #536
• Remove lil_matrix in toqito/perms/symmetric_projection.py #537

[Bchass]

Can you assign the first two to me, please

[vprusso]

@Bchass, I converted these all into issues. GitHub, unfortunately, requires you to comment on the issue itself in the thread in order for me to assign you. Once you do that, I can assign them to you. Thanks again for your interest and help, @Bchass!

[purva-thakre]

I think this issue is not as complicated as I initially thought it would be. We could simply replace all uses of sparse.matrix with sparse.array.

https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.csr_array.html#scipy.sparse.csr_array
https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.dia_array.html#scipy.sparse.dia_array
https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.lil_array.html#scipy.sparse.lil_array