Undefined reference to `ROOT::Math::GSLMinimizer::GSLMinimizer(ROOT::Math::EGSLMinimizerType)

ROOT
11

Don’t replace root-config --libs. Try with:

`root-config --cxx --cflags` -fPIC -w -g -o DoUnfolding DoUnfolding.C -L./src/ ... `root-config --libs` -lMinuit -lMathMore

see for example Using ROOT in a c++ code - #2 by Wile_E_Coyote