Graphical support, both run-time and post-processing, for MGGHAT is provided through gnuplot . gnuplot is a copyrighted but freely distributable no-cost program for 2D and 3D plots of functions and data points. If you do not already have gnuplot installed, it can be obtained by anonymous ftp. The official distribution site is ftp.dartmouth.edu. Look in the directory pub/gnuplot. Official mirrors are monu1.cc.monash.edu.au and irisa.irisa.fr.
If you choose to use run-time graphics with MGGHAT , you must have gnuplot in your executable path. If you do not use graphics at all, you do not need to have gnuplot installed.