Regarding readability, the goal is to produce a code as nice and short as the pseudo-code found in textbooks or research papers. As an illustration, here is what the Euclidean algorithm would look like:
Polynomial gcd(Polynomial p, Polynomial q) {
while(q.signum()!=0) {
Polynomial r=p.remainder(q);
p=q;
q=r;
}
return p;
}
It entails a dedicated development effort. This choice of clear
coding, enabled by java, may have consequences in terms of performance
compared to other software. But it could be worth the commitment, in
the respect that understanding an algorithm just by
looking at the code is made possible. Object-orientation
allows to hide ugly optimizations
behind a clean, easy to use interface.
Some may doubt however that java will ever be as clear as C++
because it doesn't provide operator overloading, which means that a+b
is written a.add(b), and will remain as such. The interested
reader can look at the on-going
discussion on the matter at Sun.
As for portability, it means that a lot of platforms are available at no cost, from powerful unix workstations or servers to handheld devices. To make it possible, the project is split in two parts : the engine (jscl) and the mathematical editor front-end (meditor). The engine is usable interactively or in batch mode from a java shell interpreter (like BeanShell for instance), or as a java library in any third-party application.
The front-end has currently two implementations (see below). Among others, it is intended for taking course notes. With it, a student can perform the calculations asked by their teacher fast and reliably. The plain text format should make the exchange of notes easy. The produced worksheets can be published on-line thanks to the MathML output feature, for instance on meditorworld (MathML capable browser needed, tested to work with Mozilla).
To run meditor on 1.6:
java -jar meditor.jar [file.txt]
java -Duser.home=[docs] -jar meditor.jar
Once the application is up, you may open the
docs/presentation.txt and try the examples contained there.
To have the data persisted, create an entry in the memopad with the
word "meditor" (+return) on the first line. The memo.csv that you can
optionally install (via your desktop application import) has such an
entry and several other memos containing the documentation.
Q1. When I want to do a calculation, the palm displays this error
message : jscl/text/ParseException.
A1. The auto-select has been disabled in v0.11 and subsequents because
expressions can contain newlines so there isn't any reliable means to
guess the end of selections. Select the expression with the stylus.
Q2. Do I need MathLib ?
A2. No.
Q3. How do I run the bsh examples ?
A3. Add the meditor bin directory to the path, give bin/jscl
execution privilege (unix), then type : jscl [example.bsh]
Q4. My limit input is returned unchanged. What am I doing wrong ?
A4. Nothing. The limit operation isn't implemented. It is kept because
of its MathML rendering usefulness.
Q5. Factoring the expression [insert mildly complex expression] takes
forever. Is there an endless loop ?
A5. The factorization algorithm is an attempt to re-invent polynomial
factorization from scratch, with a non-modular approach. But it is
inefficient. I need to implement a classical Berlekamp + Hensel lifting
algorithm.
Q6. Is there a tutorial ?
A6. Yes, see presentation.txt (desktop version) or the presentation
memo item (palm version).
Q7. What is the action of the buttons of the palm interface ?
A7. It is described in the buttons memo item.
Q8. Could we put the computed expression on a new line and preserve the
original input line ? It's nice in CAS systems to see a progression of
input lines and output lines so you can follow each math step that was
taken.
A8. It was possible in former versions, by terminating the input
expression with "=", and was removed when the parser was made to accept
equations (which is now disabled, by the way). As the software is meant
to be a typesetting system rather than a calculator, this is likely to
remain, despite the overhead of copy/pasting.
Q9. When will there be v2.0 for palm ?
A9. There already is. It is included in the desktop plateform package.
The other handheld versions however are discontinued.
The GNU General Public License
last updated on Thu May 15 2008