I'm trying to build the GNU gsl library using VS2005. Downloaded v1.8 of gsl and tried testing a few functions. It seems the way the download has setup the file paths has subdirectories of gsl, for example ...gsl\interpolation\gsl_interp.h, but all the individual header files have their own #include statements that list the include directories w/o the intervening subdirectories, e.g. ...gsl\gsl_interp.h. I set additional #include directories in VS properties to \gsl and one for \gsl\interpolation, but get a compiler error that one or more of the header files couldn't be located, presumably because the intervening subdirectory "interpolation" is not listed in all the header files. Am I missing something basic here about how the compiler searches for header files or do I really have to manually correct each header file's #include statements (very tedious)?