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on4now4
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Solved!

Partfrac gives crazy answers

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HP Prime

I am recently picked up an HP Prime to replace my TI-Nspire CAS and in almost every way I have used it so far I find it to be a much better device.  However, there is one thing that is really frustrating me.  The Part frac command although I am sure the answer is correct it is just ridiculous to work with.

 

I am trying to get partial fractions of (z)/((z-0.5)(z-0.8)) and the prime is giving me an answer that I can't easily type out here as it is way to long.  

 

My TI gives a real simple (40/(3(5z-4)))-(10/(3(2z-1)))

 

Is there any way to make the HP put things in simpler terms?  I have tried simplify and it goes nothing.

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Maké
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Hi!, @on4now4:

 

Welcome, to Forum !.

 

IMG_20160313_115033.jpg

 

 

In comparison, with Wolfram Alpha ... 

 

IMG_20160313_112617.jpg 

 

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
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calcpeace
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Hello on4now4,

 

I don't own a Prime but a hp 50g. I saw in your given example, that you use the numbers 0.5 or 0.8. The OS from Prime and hp 50g have a similar concept. If you type in numbers with decimal sign the calculators switch in another mode then CAS (hp 50g uses automatically the approximation mode, the Prime maybe the home mode), where such functions like partfrac don't work as expected. Try your example with the fractions 1/2 instead of 0.5 and 4/5 instead of 0.8. That may work.

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on4now4
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@calcpeace wrote:

Hello on4now4,

 

I don't own a Prime but a hp 50g. I saw in your given example, that you use the numbers 0.5 or 0.8. The OS from Prime and hp 50g have a similar concept. If you type in numbers with decimal sign the calculators switch in another mode then CAS (hp 50g uses automatically the approximation mode, the Prime maybe the home mode), where such functions like partfrac don't work as expected. Try your example with the fractions 1/2 instead of 0.5 and 4/5 instead of 0.8. That may work.


Brilliant!  This does work!  A little annoying that I have to enter as fraction, but I can live with this solution.  

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Maké
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Hi!, @calcpeace:

 

You can have, the emulator, on your PC, notebook, etc..., free, for download and install, from ... ftp://ftp.hp.com/pub/calculators/Prime/

 

Note: In the emulator, you have built in, the User Guide. 

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
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Tim_Wessman
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Hello,

 

There was actually a thread about this exact problem a few months back on another forum and the CAS author was able to resolve it. Basically, the partfrac algorithm did not correctly keep decimals (apprixmate numbers) grouped properly. That has since been resolved and if/when there is an updated prime firmware the problem will no longer be there. For example, I can now put in your original result and the returned result mathces wolfram alpha exactly.

 

The only workaround for the moment is to keep apprixmate numbers out of the input as has been discussed already.

 

pic.png

TW

Although I work for the HP calculator group as a head developer of the HP Prime, the views and opinions I post here are my own.
Maké
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Hi!, @Tim_Wessman:

 

You have reason !. If comparison, with Wolfram Alpha, indicated in my previous post (see plots), is the same result ...

 

IMG_20160313_144240.jpg

 

 

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
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calcpeace
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Hello Maké,

 

it's a truism under hp calculator afficinados that there are emulators existing, but that doesn't mean to use them.

 

I needed years learning the use of the hp 50g. This calculator is sufficient for my needs. Never change a running system.

I have RPN, RPL  and a display for graphing functions and I use let's say 20 % of the built-in possibilities.

 

If I am now a newbee with graphing calculators, so let's take the prime. I'm sorry, but that machine comes too late...for me.

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Maké
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Hi!, @calcpeace o @peacecalc ?:

 

The ultimate, HP PRIME GRAPHING CALCULATOR, don't replace HP50G, but, is equal excelent !.

I have ... HP67/HP41CV/HP28C/HP75C/HP48G+/HP49G/HP50G/HP PRIME 

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
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luiz_aug
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Hi!

 

I found some crazy answers for the partfrac command in the Prime (firmware 10077), maybe you can help me..

 

When I enter the equation: (1E6+100*x)/(x+5E3)ˆ2, I expect the answer : 

 

Captura de Tela 2016-06-02 às 00.26.29.png

 

But, instead of this, the HP gives me just the first fraction : 100/(x+5E3), missing the second one...

 

Did I forgot to set up something, or did I made something wrong ?

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