I'm using Marc 2020 and have been trying to implement user subroutines, for which I've installed Microsoft Visual Studio 2017 and Intel Fortran Compiler via Intel's oneAPI toolkits. However, I haven't been able to properly run the program with subroutines (have been trying some of the demo examples), the latest issue being:
LINK : fatal error LNK1181: cannot open input file 'C:\Program Files (x86)\Intel\oneAPI\compiler\latest\windows\bin\..\mkl\lib\intel64\mkl_intel_ilp64.lib'
Environment variables have been properly set using setvars.bat from oneAPI. However, I see that Intel paths set in Marc's include_win64.bat are wrong, but can't edit them.
I ended up contacting support, and they sent me a patch for the include_64.bat ("C:\Program Files\MSC.Software\Marc\2020.1.0\marc2020.1\tools\include_win64.bat"). However, this didn't work because the patch was meant for Marc 2020.1 and I was running Marc 2020.0. I was told then to upgrade to Marc 2021.4 (newest version at the time) and that fixed the problem. I recommend contacting support to see if you can get a similar patch. And if you don't have access to newer versions, you might still be able to update to the newest 2020 version.
I ended up contacting support, and they sent me a patch for the include_64.bat ("C:\Program Files\MSC.Software\Marc\2020.1.0\marc2020.1\tools\include_win64.bat"). However, this didn't work because the patch was meant for Marc 2020.1 and I was running Marc 2020.0. I was told then to upgrade to Marc 2021.4 (newest version at the time) and that fixed the problem. I recommend contacting support to see if you can get a similar patch. And if you don't have access to newer versions, you might still be able to update to the newest 2020 version.