Hi there, I believe there is a slight typo in gsl_types.h
Where it should be "#ifdef _WIN32" Source https://docs.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2008/b0084kay(v=vs.90) Without this change DLLs do not build. Secondly, it seems a large number of functions are missing the prefix "GSL_VARS" and cannot be used in DLLs built by MSVC. More information on this can be found here: https://github.com/ampl/gsl/issues/24#issuecomment-503330162 Kind regards Philip Deegan https://github.com/Dekken
