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Ok, here then? The strength is expressed in MSK, translation to Richter is roughly 0.75*msk + 0.5.

There are only two IX (7.5) and one X (8.0) earthquakes over a period of 600 years. This is only for the French Alps and surroundings, the most active region. I have no data for other regions.

Do the HP calculators use special HP math to perform the calculations?

Well, yes, obviously each calculator uses its own algorithms. What an odd question. Some of the firmware source has even been released, if you look hard enough (e.g.).

Or do you base your remark on brand loyalty and ignorance?

I base my remark on having fairly quickly sold a TI-89 once I started to enjoy the speed and flexibility of RPN and the tremendous amount of configurability of an HP calculator vs TI. HP totally lost the plot in hardware build quality with the HP 49G and gradually got back to nearly-OK with the 50G, but I hung on because the firmware is so good.

Also cool is the ability to program right down to Saturn / ARM assembler with the semi-official blessing of the vendor rather than the vendor trying to sue you.

I don't know why they didn't label the arrow keys on the 50G. I went through college on a 48SX, so I knew about some of the arrow key functionality, but I think only veterans of the 48 know such things. Likewise they failed to ship a full manual with the thing - I didn't even know until a couple years ago that there existed an advanced user guide on the 50G (normal guide, advanced guide - also CAS documentation). There is a ridiculous amount of hidden capability in the 50G, but they don't ship manuals for it, so nobody knows about it. And for anyone who has the 50G dropping keys on them, set the KEYTIME, another great documentation failure by HP.

As far as the swap, I'm not certain if what you call true x-y swap exists on the 50G, but if it does exist in the catalog you can probably map a soft or hard key to it. I would have to check the manual on how to do that, but I have done it before. I had to map a soft key to get back the '->Q' function that was a hard key on my 48SX (left-shift EVAL - converts a fractional number to a ratio of two integers, ex. .9225 ->Q gives 369/400).

I've tried two on Linux: wxmaxima and GIAC/Xcas. The latter is a little more powerful, especially the CAS, but not as polished. Both are scriptable, and have a "copy LaTeX" option, so there's your typeset display right there. 8)

At the end of this video there is a short part about the fluid going upwards. http://web.ujf-grenoble.fr/PHY/FOREXPER/TPhelium/p ages/Presentation%20film.html

how do we know whether it has moving parts in it or not?

RTFA:

Remember how a laser light diffract when passing through a pinhole? Infos here and here (in french). FYI, the latter university is named after the 19h century french scientist who gave his name to the Fourier transform we all know.

I guess by superimposing many diffraction patterns they are able to generate the picture. This should imply Fourier-like transforms of the source image.

Haven't tried it myself but probably worth checking out: http://www-fourier.ujf-grenoble.fr/~parisse/giac.h tml An Open Source CAS from the principle author of the HP 48/49 CAS. Available for Linux/Win/Mac/Arm.

How about XCas? I haven't seen it mentioned here yet but it seems to fit the parameters of the question pretty well. Its user interface leaves a little to be desired but it is a graphing calculator akin to a TI-89 (in fact it has a TI-89 compatibility mode), GPLed. XCas, like the TI-89, can do lots of classroom-type stuff from simple arithmetic to 3-D graphing and symbolic calculus (the biggie that students love). Maybe not so good for professional engineers but it might be just the ticket for educators and students. With a little work to pretty up that user interface. A KDE frontend would easily make it the best Free math program out there for students not in advanced math or technical courses.

Giac/Xcas is a free computer algebra system for Windows, Mac OS X and Linux/Unix. It has a compatibility mode for maple, mupad and the TI89. It is available as a standalone program (graphic or text interfaces) or as a C++ library.

http://www-fourier.ujf-grenoble.fr/~parisse/giac.h tml/

Yes, maxima...

http://maxima.sourceforge.net/

or giac...
http://www-fourier.ujf-grenoble.fr/~parisse/englis h.html

(giac, interestingly enough, runs on PDA's for a mobile solution...)

If you haven't found open source CAS, you haven't really looked...

Hello everybody,

Perhaps I am a dreamer, but since my first HP calculator I have allways dreamed for a device as easy to use as it, that it would be easy to program, with all the math capabilities it had.. and much more like a pocketpc..

Now this thecnology exist but it is focused in PDA for business people that want to keep their contacts and make some PowerPoint presentations..

But it is not all lost. I have discovered a new hope from linux on iPaq. Nowdays I am helping as betatester and spanish doc translations of a GPL project for C++ CAS (Computer Algebra System). It is in alpha stage, but it is quite useable, and its basic features are:
- Equation editor (interactive)
- Matrix writer and Spreadsheet
- Program with C like syntax
- Conections with Maple and Mupad
- Interactive geometry
-... and more

It runs on PC with Linux and MS Windows too..

Its creator is the same person who has developped hp49 and hp40 CAS, so he has experience about using this kind of system for learning, since he is professor at Grenoble University.

We share this vision about using this devices (or specific designed ones, as calculators) as a tool more for students, once they have learned the concepts. Perhaps with exams divided in a teorical part where calculators are not allowed and a practical part were you could use them.

But I go a step beyond. The cost of a low cost PDA with all this software and more (perhaps python, C compiler, or java,..) is less than a similar laptop or PC. I think this kind of devices could be a solution for people that can't earn enough money to buy a laptop and run Mathematica or Matlab on it to develop or investigate.. I think these devices are a great oportunity to third world countries to have great tools for new thecnologies learning and research..

You could see more about giac/xcas (the app I've talked) here:
http://www-fourier.ujf-grenoble.fr/~parisse/giac.h tml

"Maybe I am a dreamer, but sure I am not the only one"

Have fun,
J.Manrique
jsmanrique_lopez@yahoo.es

If you run linux on it you could try xcas:
http://www-fourier.ujf-grenoble.fr/~parisse/giac.h tml

It is a nice software in alpga stage but quite usable with:
- CAS (Computer Algebra System)
- Interactive geometry
- Equation editor (interactive)
- Matrix writer
- Spreadsheet
- You can program functions and more in C like syntax
-...

I run it on my iPaq3130 with linux and it is fantastic.. and GPL ;-)

have fun,
J.Manrique
jsmanrique_lopez@yahoo.es

If you run linux you could run a complete CAS (Computer Algebra System) with GPL in your PDA. Look here for more info:
http://www-fourier.ujf-grenoble.fr/~parisse/giac.h tml

It has all you would like for a CAS and more:
- Matrix writer
- Equation editor
- Programmable
- Spread-sheet
-...

Have fun,
J.Manrique
jsmanrique_lopez@yahoo.es