Bugfix in uni5_for.c and in test

[TimSiebert1]

Hi,
this PR includes a bugfix in

• uni5_for.c
• traceOperatorVector.cpp

uni5_for.c:
There was a bug when calculating the derivative of fmax or fmin at the tie-point with the tape-based forward mode. In principle, there was a missing else that encapsulates the pointer increment: Targ1++ and Targ2++. Due to the missing else, the pointers got sometimes incremented twice, when the loop macro FOR_0_LE_i_LT_k was not defined.

traceOperatorVector.cpp
I also corrected the tests for the tie-points of fmax and fmin, based on following assumption for the "correct" behavior:
If we have two adouble variables a and b that are equal, the derivative yd of fmax calculated by fov_forward is given by the column-wise maximum of the provided tangent matrix xd. Meaning, if xd[0][0] = 1.3, xd[1][0] = -1.3, xd[0][1] = -1.3, xd[1][1] = 4.0 we would get yd = [1.3, 4.0] (= [std::fmax(xd[0][0], xd[1][0]), std::fmax(xd[0][1], xd[1][1])]). If on the other hand, b is a constant (double) yd is given by the maximum between the corresponding xd entries and 0.0 (i.e. [std::fmax(xd[0][0], 0.0), std::fmx(xd[0][1], 0.0)]).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.25%. Comparing base (a02023b) to head (3c1f1ed).
Report is 14 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #88      +/-   ##
==========================================
+ Coverage   65.95%   66.25%   +0.29%     
==========================================
  Files          51       51              
  Lines       26473    26686     +213     
  Branches     1843     1843              
==========================================
+ Hits        17461    17680     +219     
+ Misses       9012     9006       -6     

Flag	Coverage Δ
unittests	66.25% <100.00%> (+0.29%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.