Installation is very straightforward: xelem is a tcl script. It
requires wish interpreter to be in /usr/local/bin/wishx; if that wish
interpreter has the xygraph widget compiled in, plotting functions
will be available (graph-1.1.tar.Z is available at
harbor.ecn.purdue.edu). Other than that, the xelem program should use plain
Tk3.2 wish, but I did not check that (I have extended Tcl compiled together
with wish)

A simple icon bitmap is included that may be put in
/usr/local/lib/bitmaps.

The example initialization file should be placed in ~/.xelemrc (this
file does require math extensions from TclX). It implements a
calculation of critical angle for neutron scattering. 

The initialization file illustrates the use of GetTotal command
provided by the main program:

	GetTotal quantity compound

will calculate the sum total of the quantity (e.g. "atomic mass")
over all elements of the compound, which is given as a chemical
formula (e.g. Fe2(H2O)3).

The main file also defines a procedure 

	labent window name variable InitValue

that creates a frame with label and entry widgets, as a convenient
input widget. The InitValue argument is optional and defaults to {}.

