This is an example of a simple hence graph which computes mandelbrots.
The parameters are set up in the start node, the mandelbrot is computed in
the tile node, and the output is written to a file (mandel.out in your home
directory) from the collect node.  There is no point to this example other than
to introduce you to hence graphs; the graph is completely sequential and
therefore there is no way hence can do any of the operations in parallel.

To run the example, start htool.  Load the graph demo0.gr by clicking the
"graph" button and selecting demo0.gr.  Click "compose" to look at the graph.
Click config and add the names of the machine(s) you will use, and some
arbitrary cost (say 1 for now) in each block.  Save the cost matrix by
clicking "store".  Click "build" to get into build mode, then click
"write wrappers", "write makefile", "make clean", "make", and "make install"
in that order (assuming all goes well).  Then click "start pvm" and "execute".
Then click "trace", the satelite dish, and the "play" button (a right pointing
triangle) to watch the graph execute.

The format of the output file is width*height (currently 65536) bytes of
raw data.  Display using the values of the bytes as pixel values with some
interesting colormap, preferably with contrast between adjacent colors.

The program xpx.c in this directory can be used to display these images.  To
compile use:
	cc xpx.c -o xpx -lX11 -lm

To use the display program (from a color display) use:

	xpx -color 256 256 ~/mandel.out
