Added Function for Generating LDPC Tanner Graphs using the Progressive Edge Growth (PEG) Algorithm

[vivek-kumar9696]

This solves the issue #70 by implementing the required function and necessary tests.

• Implementation: Placed the implementation, generate_ldpc_peg.py in the src_python/ldpc/codes directory.

• Testing: Added corresponding tests in the python_test directory by modifying test_codes.py. Added tests for:

• Test that generate_ldpc_peg returns a CSR matrix of correct shape and type, test_generate_ldpc_peg_output_type_and_shape()

• Test that all entries of the generated matrix are binary (0 or 1), test_generate_ldpc_peg_binary_entries()

• Test that each variable node has exactly dv edges and each check node has degree at most dc, test_generate_ldpc_peg_degrees

• Test that the generated matrix contains no 4-cycles, i.e. any two variable nodes share at most one common check neighbor, test_generate_ldpc_peg_no_four_cycles

[quantumgizmos]

Thank you for the PR. I have assigned you to the issue.

[vivek-kumar9696]

@quantumgizmos ,
Thank you. I remember that you also required a cython wrapper. Apologies, I did not get time to take a look at it. But if this is a correct implementation, I will raise a new issue and modify to add a cython wrapper asap.

[quantumgizmos]

@vivek-kumar9696 Thank you. A cython wrapper would be great!