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Author Topic: Bugs and Requested Features with the HP Prime and Related Software  (Read 62491 times)

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Offline sailerboy

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #30 on: September 27, 2013, 01:24:37 pm »
I've got another question that may seem simple. How does one do Polynomial division?

For example, I entered (x^7+4x^3+8)/(x^2+2) in the cas mode, and it just rewrites it as a fraction. I tried using "simplify()", but that doesn't change it at all. To do division, I have to go to the on screen menu, select CAS, select Polynomial, Algebra, Quotient, and input the function, but even then, I get "Gen [int] Error: Bad Argument Type"

I know that this was alluded to in Cemetech's review of the HP Prime, but he never really gave a solution for the problem beyond just saying that it was an indescriptive error.

Also, one thing I just noticed: If I wanted to find the limit of, say, 1/x as x goes to zero from the positive side, I have to enter "1" instead of just entering "+", likewise if i wanted to find it from the negative side, I would have to enter "-1" instead of just "-".

« Last Edit: September 27, 2013, 01:33:29 pm by sailerboy »
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Offline iconmaster

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #31 on: September 27, 2013, 03:40:07 pm »
Today's Bug:




Today's Suggestion: the right arrow character should be a synonym for -> in the CAS. Having -> when a perfectly good UTF character exists is quite odd.
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Offline timwessman

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #32 on: September 27, 2013, 03:42:35 pm »
Quote from: sailerboy on September 27, 2013, 01:24:37 pm
I've got another question that may seem simple. How does one do Polynomial division?
...
To do division, I have to go to the on screen menu, select CAS, select Polynomial, Algebra, Quotient,

Nearly there. Put your first poly in the first argument, and the second in position 2. Just like the nspire, it is a 2 argument function.

quo(x^7+4x^3+8,x^2+2)

Quote
Also, one thing I just noticed: If I wanted to find the limit of, say, 1/x as x goes to zero from the positive side, I have to enter "1" instead of just entering "+", likewise if i wanted to find it from the negative side, I would have to enter "-1" instead of just "-".

Yes. It can take either '+' or '-' with tick marks, but not + or - directly as it is interpreted as an operator. This is an item that is in the list of things to improve. It displays correctly on calculation, but the input needs enhancement here.
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Offline sailerboy

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #33 on: September 27, 2013, 04:47:30 pm »
Quote from: timwessman on September 27, 2013, 03:42:35 pm

Nearly there. Put your first poly in the first argument, and the second in position 2. Just like the nspire, it is a 2 argument function.

quo(x^7+4x^3+8,x^2+2)

That seems like a lot of steps to get to something that occurs fairly often. Why can't I just do (polynomial 1)/(polynomial 2) for division?
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Offline iconmaster

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #34 on: September 27, 2013, 05:00:25 pm »
Quote from: sailerboy on September 27, 2013, 04:47:30 pm
That seems like a lot of steps to get to something that occurs fairly often. Why can't I just do (polynomial 1)/(polynomial 2) for division?

Is your Simplify level on Off? If it is, remember that the CAS won't change your variables at all. I always have it on Maximum.
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Offline sailerboy

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #35 on: September 27, 2013, 05:23:43 pm »
Quote from: iconmaster on September 27, 2013, 05:00:25 pm
Quote from: sailerboy on September 27, 2013, 04:47:30 pm
That seems like a lot of steps to get to something that occurs fairly often. Why can't I just do (polynomial 1)/(polynomial 2) for division?

Is your Simplify level on Off? If it is, remember that the CAS won't change your variables at all. I always have it on Maximum.


I have simplify off since CAS does weird things sometimes, but there's the simplify button on the screen. I tried pushing that and it had no effect.
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Offline timwessman

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #36 on: September 27, 2013, 05:23:44 pm »
Quote
Quote
quo(x^7+4x^3+8,x^2+2)

That seems like a lot of steps to get to something that occurs fairly often. Why can't I just do (polynomial 1)/(polynomial 2) for division?

You can. However, your divisor in this case is not a clean piece of your first polynomial and leaves a remainder. Which calculator will directly take that specific input and spit out x^5-2*x+8x? I would call that a bug.  Observe: http://www.wolframalpha.com/input/?i=%28x^7%2B4x^3%2B8%29%2F%28x^2%2B2%29

Try this one: (21*x^3-35*x^2)/(7*x). That one will cleanly work out (no remainder) and reduce as you are expecting.
« Last Edit: September 27, 2013, 05:26:13 pm by timwessman »
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Offline timwessman

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #37 on: September 27, 2013, 05:36:20 pm »
Quote from: iconmaster on September 27, 2013, 03:40:07 pm
Today's Bug:


Eh? What is wrong with this? You have a 2 item vector with 2 sub vectors (size of 1 and size of 2)?

Quote


Today's Suggestion: the right arrow character should be a synonym for -> in the CAS. Having -> when a perfectly good UTF character exists is quite odd.

Not seeing what this image is supposed to show... :-?
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Offline iconmaster

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #38 on: September 27, 2013, 05:59:36 pm »
It might be me being stupid with math, but why does that return "n"? That's a string! Also, I thought the correct format for vectors was [[x],[y]], not [[x][y]]...
« Last Edit: September 27, 2013, 06:01:52 pm by iconmaster »
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Offline sailerboy

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #39 on: September 28, 2013, 12:17:31 am »
Another bug: Trying to differentiate the equation (2/3)(x^2+1)^(3/2) gives weird output. Here is the image:



And here is the expected result: http://www.wolframalpha.com/input/?i=differentiate+%282%2F3%29%28x%5E2%2B1%29%5E%283%2F2%29

Also, with the TI Nspire, i was able to quickly and easily able to create functions for certain math problems, like so:

f1(x,a,b):=x^2+ax+b

And for any value I then typed in for x, a, and b, it would substitute that in the equation. Is there an easy way to do something like this in the Prime?
« Last Edit: September 28, 2013, 01:11:14 am by sailerboy »
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Offline iconmaster

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #40 on: September 28, 2013, 09:13:29 am »
Today's Bug: Doing a numerical expression of the form (1)2 in the CAS results in an error. The CAS does not handle implicit multiplication well.

Today's Suggestion: I wish there was a | key in the Math palette, as I use that character in assumption statements a lot.
« Last Edit: September 28, 2013, 09:14:01 am by iconmaster »
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Offline SpiroH

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #41 on: September 28, 2013, 09:22:17 am »
Quote from: sailerboy on September 28, 2013, 12:17:31 am
Another bug: Trying to differentiate the equation (2/3)(x^2+1)^(3/2) gives weird output. Here is the image:
Yeah, that's a very odd output indeed, to say the least? I wonder, have they thoroughly tested symbolic differentiation?
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Offline fhub

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #42 on: September 28, 2013, 10:26:47 am »
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« Last Edit: November 09, 2014, 08:04:20 am by fhub »
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Offline SpiroH

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #43 on: September 28, 2013, 10:33:28 am »
Quote from: fhub on September 28, 2013, 10:26:47 am
Quote from: SpiroH on September 28, 2013, 09:22:17 am
Quote from: sailerboy on September 28, 2013, 12:17:31 am
Another bug: Trying to differentiate the equation (2/3)(x^2+1)^(3/2) gives weird output. Here is the image:
Yeah, that's a very odd output indeed, to say the least? I wonder, have they thoroughly tested symbolic differentiation?
The problem is not the differentiation, the problem is even earlier in the interpretation of the expression (2/3)(x^2+1)^(3/2).

If you enter the same expression but with an explicit multiplication character, i.e. (2/3)*(x^2+1)^(3/2), then everything works fine.
But without this * after (2/3) this expression seems to a completely different thing, not even an usual math expression but a 'function' like f((x^2+1)^(3/2)) with '2/3' as 'name' of the function, i.e. '2/3'(.....). And that's the reason why the differentiation doesn't work for this 'function' of course!
Just try to experiment a bit with this strange expression and you'll see that is not anything you would expect - crazy indeed!

Franz

Hi Franz, long time no see. Welcome back!
Yeah, it ought to be something 'stupid' like that! I mean, no implicit times operator! Cheers,
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Offline Lionel Debroux

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Re: Bugs and Requested Features with the HP Prime and Related Software
« Reply #44 on: September 28, 2013, 10:36:31 am »
Quote
I wonder, have they thoroughly tested symbolic differentiation?
At least, the Prime is still a very young platform, unlike the Nspire, whose whole Nspire OS 3.x family has been a disaster for correctness...

And yeah, the DWIM principle (or at least, what looks like something along those lines) seem to produce many strange effects and racking up a few nerves on MoHPC and beyond.
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