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?