function gm_errmsg(filename)disp(sprintf('You have executed m-file %s.m.  This m-file is not meant', filename))disp('to be executed.  Instead, you should be executing a mex file named')disp(sprintf('%s.  The fact that %s.m has been executed means that either QMG is not', filename, filename))disp('fully built, and hence some mex files are missing, or else your Matlab')disp('path is not set up correctly.  The path should be set by the file named')disp('startup.m in QMG_ROOT/ex.  This file should be run prior to executing')disp('any QMG files.')emsg = sprintf('missing mex file %s', filename);error(emsg)