mex not finding eigen library

I'm trying to use the Eigen 3.3.5 library with mex using Matlab2018a and OS X 10.13.6 and gcc 4.2.1. I installed it into /usr/local/lib using cmake and also put a symbolic link to it in /usr/local/include. I named the directory eigen. The terminal command gcc -xc -E -v - indicates that /usr/local/include is on the include path for gcc. Nonetheless, the command mex ep_bootdat.c (which has #include <Eigen>) results in "error: 'Eigen' file not found" I've also tried #include <eigen/Eigen> and #include <eigen>. I've also tried mex -I/usr/local/include/eigen/ ep_bootdat.c. Nothing seems to help. Can anyone suggest what might be going wrong?

Answer 1

[Joseph]

okay, after much mucking around, I found the solution, which was #include <Eigen/Dense> in the .c file and mex ep_bootdat.c -I/usr/local/include/eigen3/ as the Matlab invocation. eigen3 was placed in /usr/local/include by the "make install" command that one is supposed to do after the cmake command, according to the eigen INSTALL documenation.

Answer 2

[Joseph]

footnote - apparently it needs to be C++ (as in ep_bootdat.cc -I/usr/local/include/eigen3/) otherwise it errors out with a:

 /usr/local/include/eigen3/Eigen/Core:82:12: fatal error: 'new' file not found
  #include <new>