[ncassereau]

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Motivation and context / Related issue

Attempt to resolve #311.
This bug appeared on multiple occasions (#281, #311 as far as I'm aware) due to the fact that line_search_armijo could return None as an alpha if no valid value was found. This behaviour is faulty and might be a cause of bugs in the future. From now on, this function returns 0 if no alpha value was found, meaning convergence point was reached.

How has this been tested (if it applies)

Tested with the data provided by issue #311

Checklist

• The documentation is up-to-date with the changes I made.
• I have read the CONTRIBUTING document.
• All tests passed, and additional code has been covered with new tests.

[codecov]

Codecov Report

Merging #312 (d036d17) into master (f4b363d) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #312      +/-   ##
==========================================
+ Coverage   93.39%   93.43%   +0.03%     
==========================================
  Files          21       21              
  Lines        4888     4887       -1     
==========================================
+ Hits         4565     4566       +1     
+ Misses        323      321       -2