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HP Calculators

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Orwell
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05 Dec 2010, 12:11 am

mcg wrote:
Orwell wrote:
Out of curiosity, what sort of syntax do you have to use on the HP graphing calculators (or other RPN calculators) when you want to evaluate an integral, solve a system of equations, or do complicated symbolic manipulation?
You can store symbolic expressions on the stack and manipulate them with RPN. They look really pretty, too. Then you can invoke various functions on them such as integration. There's also the equation writer where you can just enter the integral exactly like it appears in the textbook and store it on the stack. Then you press the eval key and you get your answer. You never ever need to end up typing alphanumeric strings on the calculator keypad, even when programming in RPL.

Well, for example, if I wanted to evaluate a definite integral on my TI-89, I would type in something like:
∫(x^2+sin(x)),x,0,10) and then press enter. This is basically identical to the syntax in typical PC-based CAS programs.
What is the syntax for a similar function on an RPN calculator?


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mcg
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05 Dec 2010, 12:51 am

Well there are a few ways to do it.

You could use this thing called the equation writer where you could just enter the definite integral exactly like it appears in the textbook (the integral function is a shifted key on the keypad). I don't really know how to explain how the interface works, but basically you just use the arrow keys to enter equations exactly as they would look in a textbook.

I personally would take the RPN approach: [X] [Enter] (pushes a symbolic X onto the stack) [X^2] [X] [Enter] [SIN(X)] [+]

This would leave x^2+sin(x) on the stack. (Alternatively you could enter that directly into the equation writer to get it onto the stack). Then I would invoke the INTVX function with one of the function keys along the top (functions take their arguments from the stack).

This would leave the indefinate integral of that function on the stack: (X^3)/3-Cos(X)

Then I would do [0] [Enter] [10] and press the function key for the PREVAL function to calculate the definate integral.



Orwell
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05 Dec 2010, 1:00 am

Is there an HP50 emulator, or just a desktop RPN graphic calculator? I think I would have to actually go through and push the buttons to see what you're describing.


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mcg
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05 Dec 2010, 1:10 am

There's an OS X port of Emu 48 here: http://www.hpcalc.org/hp49/pc/emulators/ (never tried it myself, so I can't vouch for it)

If there's not a 50g rom included in that package then you can get it here: http://www.educalc.net/ftp/educalc/HP3in1Emu.zip



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14 Dec 2010, 4:50 am

I agree with the OP about build quality, tactile euphoria, etc. of the HP programmable calculators. I had the 15C when I was in avionics school. My roommate had one similar (or the same) as the one pictured in the OP. I had fun writing programs for mine to let me play blackjack, high/low and other games.

If you have a smartphone, you should do a few searches for open source RPN emulators. Good luck!


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Orwell
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14 Dec 2010, 10:23 am

mcg wrote:
There's an OS X port of Emu 48 here: http://www.hpcalc.org/hp49/pc/emulators/ (never tried it myself, so I can't vouch for it)

If there's not a 50g rom included in that package then you can get it here: http://www.educalc.net/ftp/educalc/HP3in1Emu.zip

The installation instructions on the Linux build instruct me to delete my shell. ('sudo rm /bin/sh') I don't trust any software author who would suggest deleting sh.


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mcg
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14 Dec 2010, 11:23 am

Oh, I though you were using Mac OS X for some reason.

Anyways, /bin/sh is usually just a symlink. I haven't seen the specific instructions you're referring too so I'm not sure of the context, but it is probably for Ubuntu users to switch the shell from dash to bash before running the makefile (I suspect the next instruction would be something like ln -s /bin/bash /bin/sh). If that's the case, you can just add SHELL=/bin/bash to the top of the makefile rather than relinking /bin/sh to /bin/bash.