I installed Microsoft Visual Studio 2015 Professional, however "mex -setup" still does not successfully find the Microsoft Visual C++ 2015 compiler. This can be seen from the following output snippet of running the command "mex -v -setup":
... Looking for compiler 'Microsoft Visual C++ 2015 Professional (C)' ... ... Looking for registry setting 'HKLM\SOFTWARE\Microsoft\VisualStudio\SxS\VS7' 14.0 ...No. ... Looking for registry setting 'HKCU\SOFTWARE\Microsoft\VisualStudio\SxS\VS7' 14.0 ...No. ... Looking for registry setting 'HKLM\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\SxS\VS7' 14.0 ...Yes ('C:\Program Files (x86)\Microsoft Visual Studio 14.0\'). ... Looking for file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\cl.exe' ...No. Did not find installed compiler 'Microsoft Visual C++ 2015 Professional (C)'. Error using mex No supported compiler or SDK was found. You can install the freely available MinGW-w64 C/C++ compiler; see Install MinGW-w64 Compiler. For more options, visit http://www.mathworks.com/support/compilers/R2016a/win64.html.
Why is this occurring?
What we see in the output above is that indeed Microsoft Visual Studio 2015 has been installed, but the actual C/C++ compiler is missing. This is likely caused by having installed Microsoft Visual Studio 2015 Professional using the "Typical" setup option which will not install the Visual C/C++ compiler by default. This is seen in Microsoft's documentation:
To resolve this issue, re-run the Visual Studio 2015 installer again and choose to perform a "Custom" setup. Then during installation, make sure to enable "Visual C++" under "Programming Languages".