Best solution (f-value and params) printed as best by CMASolutions object differs from best seen solution

[kostayScr]

When doing (or using cmasols.print()):
std::stringstream s; s << cmasols << std::endl;
Example output is:
best solution => f-value=-7.15984 / fevals=1404 / sigma=39.6261 / iter=234 / elaps=516809ms / x=4.77428 9.80868
That is not correct though.
Actual best for this example:
Correct f-vlaue: -8.03673
The output is pretty random, because it outputs Current best solution, not the best seen candidate.
The bug is in cmasolutions.cc, line 265:
out << "best solution => f-value=" << best_candidate().get_fvalue() << " / fevals=" << _nevals << " / sigma=" << _sigma << " / iter=" << _niter << " / elaps=" << _elapsed_time << "ms" << " / x=" << gp.pheno(best_candidate().get_x_dvec()).transpose();
The used best_candidate() member function is wrong. Must be get_best_seen_candidate(). The correct results in the example were obtained using it.
The current output is very random, can be heavily different from real best value i.e. you m ay think that it doesn't converge at all with this lambda, while it converged nicely.

[beniz]

Hi, this is not a bug, the best (or final) value is that of the current (or final) iteration, to get best value over the full run, the call to get_best_seen_candidate() is the right way to do it, as you are mentioning.

This comment might help you as well, #195 (comment)

[kostayScr]

Ok but the description is heavily misleading then.
It says "best solution" but it's not the best solution that has been found..
These solutions can often heavily differentiate e.g. -3 - which was good enough and +6, as well as an entirely different parameters values region.
I'm not the only one confused by it , as you saw in the #195.
Btw would be nice to catch some dumb errors like this:
GenoPheno<pwqBoundStrategy, linScalingStrategy> gp( mins.data(), maxes.data(), dim ); CMAParameters<decltype(gp)> cmaparams( x0, sigma, lambda, 0, gp ); CMASolutions cmasols = cmaes<>( optimFn, cmaparams );// <-- no decltype(gp) given, but compiles without a hitch