Since my plans for a Linux system are on hold, I'm trying to shore up my Windows machine to do some calculations. I've been having trouble with MinGW/MSYS lately. I was able to compile GMP, but wasn't able to do anything with it -- anything I did gave me error messages saying it couldn't find gmp.h. (And yes, I did a make install.) After searching through the settings, I found that it was nothing more than a problem with my search directories: if I compiled with Code (Text): gcc blah.c -o blah -I /usr/local/include -L /usr/local/lib -lgmp rather than simply Code (Text): gcc blah.c -o blah -lgmp it worked properly. But when I'm making a large piece of software, I can't just change all gcc command lines in the makefile -- I don't even know how half the thing works, let alone how to properly modify it. This seems like a problem with a simple solution, but I haven't been able to find it. I can modify the $PATH to include both directories, but that doesn't work. I tried passing --libdir and --includedir to configure, but that had no apparent effect at all. Any ideas?