ENC: Trouble with symbolic on the Octave

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ENC: Trouble with symbolic on the Octave

Paulo Roberto
I'm studying a discipline where we have to do calculations in Matlab. I preferred to use Octave because it's a free software and the book I use is one about Matlab (Matlab An Introduction with Applications by Amos Gilat).

My OS is Windows 7, the Octave is 4.2.1, the Symbolic Package is 2.5.0 and to implement Symbolic Math, I use the Anaconda Package, which has the version 2.7.13 of Python and 1.0 for SymPy. But since the commands I've quotes are not implemented in Octave, I'll leave them aside and go on...

Thank you very much for your help!

Paulo.


De: "Doug Stewart" <[hidden email]>
Enviada: 2017/06/12 11:35:57
Para: [hidden email]
Cc:  [hidden email]
Assunto:  Re: Trouble with symbolic on the Octave

 

 

 
 
On Mon, Jun 12, 2017 at 10:26 AM, Paulo Roberto <p_roberto@...> wrote:
Hello, Doug!

Some examples below:

1)
>> syms x y
>> S=(x^2+x-exp(x))*(x+3)
S = (sym)

              / 2        x\
  (x + 3)*\x  + x - e /

>> F=collect(S)
error: 'collect' undefined near line 1 column 3
>>
it was expected F=x^3+4*x^2+(-exp(x)+3)*x-3*exp(x)

2)
>> syms x y
>> S=x*(x*(x-8)+10)-5
S = (sym) x*(x*(x - 8) + 10) - 5
>> SA=simplify(S)
SA = (sym) x*(x*(x - 8) + 10) - 5
>>
it was expected SA=x^3-8*x^2+10*x-5

3)
>> sym x
ans = (sym) x
>> s=(x^3-4*x^2+16*x)/(x^3+64)
s = (sym)

   3      2
  x  - 4*x  + 16*x
  ----------------
       3
      x  + 64

>> F=simple(S)
error: 'simple' undefined near line 1 column 3
>>
it was expected F=x/(x+4)

I'll appreciate any assistance!

Thanks,

Paulo Roberto.
 

 

 
you are using command that are not implemented.  what software are you currently used to? 
 

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Re: ENC: Trouble with symbolic on the Octave

Colin Macdonald-2
On 12/06/17 08:10 AM, Paulo Roberto wrote:

> I'm studying a discipline where we have to do calculations in Matlab. I
> preferred to use Octave because it's a free software and the book I use
> is one about Matlab (Matlab An Introduction with Applications by Amos
> Gilat).
>
> My OS is Windows 7, the Octave is 4.2.1, the Symbolic Package is 2.5.0
> and to implement Symbolic Math, I use the Anaconda Package, which has
> the version 2.7.13 of Python and 1.0 for SymPy. But since the commands
> I've quotes are not implemented in Octave, I'll leave them aside and go
> on...

Even better, would be to file a bug for the missing "collect" function at:

https://github.com/cbm755/octsympy/issues

Your other two examples should work using "expand" and "simplify"
respectively.

Note: there is no expectation that simplify-type commands work the same
in different software platforms, different versions etc: AFAIK, its not
a well-defined operation.

Colin


> *De: *"Doug Stewart" <[hidden email]>
> *Enviada: *2017/06/12 11:35:57
> *Para: *[hidden email]
> *Cc: *  [hidden email]
> *Assunto: *  Re: Trouble with symbolic on the Octave
>
> On Mon, Jun 12, 2017 at 10:26 AM, Paulo Roberto <[hidden email]>
> wrote:
>
>     Hello, Doug!
>
>     Some examples below:
>
>     1)
>      >> syms x y
>      >> S=(x^2+x-exp(x))*(x+3)
>     S = (sym)
>
>                    / 2        x\
>        (x + 3)*\x  + x - e /
>
>      >> F=collect(S)
>     error: 'collect' undefined near line 1 column 3
>      >>
>     it was expected F=x^3+4*x^2+(-exp(x)+3)*x-3*exp(x)
>
>     2)
>      >> syms x y
>      >> S=x*(x*(x-8)+10)-5
>     S = (sym) x*(x*(x - 8) + 10) - 5
>      >> SA=simplify(S)
>     SA = (sym) x*(x*(x - 8) + 10) - 5
>      >>
>     it was expected SA=x^3-8*x^2+10*x-5
>
>     3)
>      >> sym x
>     ans = (sym) x
>      >> s=(x^3-4*x^2+16*x)/(x^3+64)
>     s = (sym)
>
>         3      2
>        x  - 4*x  + 16*x
>        ----------------
>             3
>            x  + 64
>
>      >> F=simple(S)
>     error: 'simple' undefined near line 1 column 3
>      >>
>     it was expected F=x/(x+4)
>
>     I'll appreciate any assistance!
>
>     Thanks,
>
>     Paulo Roberto.
>
> you are using command that are not implemented.  what software are you
> currently used to?
>
>
> _______________________________________________
> Help-octave mailing list
> [hidden email]
> https://lists.gnu.org/mailman/listinfo/help-octave
>


--
Colin Macdonald
Associate Professor
Dept of Math, UBC

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