(Comp.sys.handhelds)
Item: 2264 by fseipel at hpuxa.ircc.ohio-state.edu
Author: [Frank Seipel]
  Subj: HP-48SX; subroutine (subscripted chemical formulae)
  Date: Thu Feb 28 1991

Chemical Formula Display Utility (CFD)
by Frank Seipel

 The following is a short RPL subroutine, to be called CFD, and a short
example program, Call, which demonstrates its use. The purpose of CFD is to
provide a means of displaying subscripted chemical formulae in user programs.

CFD takes three arguments, an x-coordinate (binary integer), a y-coordinate
(binary integer), and a text string (formula to display). The formula will be
superimposed on PICT, beginning at the location specified by your coordinates.
Any numerals in the formula will be subscripted, so as to appear like a
chemical formula you would write on paper. Optionally you may include an '@'
character in the string. This is interpreted as: go to column #50d and add the
rest of the string to PICT at once, without subscripts -- this may be useful
in right-justifying the names of compounds next to their names (see example
program).  See page 324 of the manual for a diagram showing the binary
coordinate system; the upper left corner is { #0d #0d }, the bottom right
corner is { #130 #63 }. To type '@' on the HP-48SX, key in: alpha, followed by
blue shift, and then ENTER.

I realize this program is rather straightforward, but it seems as if it would
be something which will be written over and over by many people so I decided
to post it to the net. I am working on a program to let you scroll through
subscripted formulas of common compounds. Once I have this working I will
write a program to compute specific enthalpy at a given temperature, and to
display other physical properties such as boiling points, heats of formation,
vaporization, and combustion.

 If you didn't guess, YES, I am studying Chemical Engineering...

---------------- STO this program as 'Call' ------------------------

%%HP: T(3)A(R)F(.);
\<< # 0d # 22d "H2SO4@Sulfuric Acid" CFD { } PVIEW
\>>

---------------- Second example ------------------------------------

Example calling sequence:

4:                      #0d
3:                      #0d
2:   "CH3CH2CH3@Propane"
1:                      CFD

Then hit orange-shift-graph to display PICT to see the subscripted formula in
the upper right hand corner of screen. See also 'Call', above.

Note: You may wish to adjust how far '@' goes over horizontally, depending
on the length of your formula.