fix impedance

[AurelienJaquier]

Description

• When stimulus starts at 0 for impedance (which can happen often), use steady_state_voltage_stimend to get holding voltage, and equivalent for holding current. Since at the end of the stimulus, we expect the current and voltage to vary rapidly around the holding value, this is a good enough proxy to get it.
• implemented test_steady_state_current_stimend, along with documentation and test
• fixed current interpolation
• fixed stim_end value in impedance test data file

Checklist:

• Unit tests are added to cover the changes (skip if not applicable).
• The changes are mentioned in the documentation (skip if not applicable).
• CHANGELOG file is updated (skip if not applicable).

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.63636% with 5 lines in your changes missing coverage. Please review.

Project coverage is 92.24%. Comparing base (2cddd26) to head (9ed2241).
Report is 23 commits behind head on master.

Files	Patch %	Lines
efel/cppcore/Subthreshold.cpp	86.95%	0 Missing and 3 partials ⚠️
efel/pyfeatures/pyfeatures.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #402      +/-   ##
==========================================
+ Coverage   91.73%   92.24%   +0.51%     
==========================================
  Files          36       39       +3     
  Lines        6278     7389    +1111     
  Branches     2033     2293     +260     
==========================================
+ Hits         5759     6816    +1057     
- Misses        266      289      +23     
- Partials      253      284      +31     

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[ilkilic]

I think you meant steady_state_voltage_stimend

[AurelienJaquier]

done in latest commit

[ilkilic]

you can even compute the mean inside the if block

[AurelienJaquier]

done in latest commit

[ilkilic]

Formidable! Thank you

[ilkilic]

Looks good!