To install, edit the variables in the Makefile and type 'make install'.
See comments to these variables for guidance.

If the wish interpreter has the blt_graph widget compiled in, plotting
functions will be available (BLT widget set is available from the
current Tcl archives). Other than that, the xelem program should use
plain Tk3.6 wish, but I did not check that (I have extended Tcl
compiled together with wish)

The example initialization file may be placed in ~/.xelemrc (this file
does require math extensions (sqrt, etc.) from TclX). It implements a
calculation of critical angle for neutron scattering off flat interfaces
of arbitrary chemical compounds.

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 {}.

