Article 4658 of comp.sys.handhelds:
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From: fseipel@hpuxa.ircc.ohio-state.edu (Frank Seipel)
Newsgroups: comp.sys.handhelds
Subject: HP-48SX; subroutine (subscripted chemical formulae)
Message-ID: <1991Feb28.213833.14277@magnus.ircc.ohio-state.edu>
Date: 28 Feb 91 21:38:33 GMT
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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 'CFD' --------------------

%%HP: T(3)A(R)F(.);
\<< 0 \-> px py str cn
  \<< 1 str SIZE
    FOR j str j j
SUB DUP NUM 'cn'
STO
      IF '57\>=cn AND
cn\>=48'
      THEN 1 \->GROB
PICT SWAP px py 4 +
2 \->LIST SWAP REPL
px 4 + 'px' STO
      ELSE DUP
        IF "@" SAME
        THEN DROP
str DUP SIZE j 1 +
SWAP SUB 2 \->GROB
PICT SWAP # 50d py
2 \->LIST SWAP REPL '
j=80' DEFINE
        ELSE 2
\->GROB PICT SWAP px
py 2 \->LIST SWAP
REPL px 6 + 'px'
STO
        END
      END
    NEXT
  \>>
\>>

<END OF CDF>

---------------- 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.


