a sequence of variables

[chu-ching huang]

Hi,

Maybe this had been discussed:

how to define a sequence of variables (by symbols), {x_1,x_2,---,x_n}
in case n is also a variable?

Thanks

[Friedrich Hagedorn]

Do you want this:

In [1]: var('x_1 x_2 x_n')
Out[1]: (x_1, x_2, x_n)

In [2]: x_1 + x_2 + x_n
Out[2]: x_1 + x_2 + x_n

By,

Friedrich

[Fabian Seoane]

You can also use DeferredVector:
In [1]: a = DeferredVector('a')

In [2]: a[1] + a[2] + a[3] + a[4] + a[54653656]
Out[2]: a[1] + a[2] + a[3] + a[4] + a[54653656]

just that the class lacks documentation, see http://code.google.com/p/sympy/issues/detail?id=1268
 

By,

 Friedrich

--
Fabian, http://fseoane.net/blog/

[chu-ching huang]

Just rebuild sympy-git source and test the following:

from sympy import *
a=DeferredVector('a')
b=DeferredVector('b')
n=10
A=eye(11)
a=Matrix(1,n,lambda i,j: 'a%g' %j)
b=Matrix(1,n,lambda i,j: 'b%g' %j)
A[0,1:]=a
A[1:,0]=b.transpose()
A.det()

and it shows the right answer:

1 - a0*b0 - a1*b1 - a2*b2 - a3*b3 - a4*b4 - a5*b5 - a6*b6 - a7*b7 -
a8*b8 - a9*b9

Thanks all.

Another suggestion is about the sympy documentation. I don't know how
"sympy" manage the doc soruce and create the doc in html or pdf
format.

Then I try another way to make "interactive" document of sympy as
follows:

1. Use TeXmacs to import (or open) sympy doc ( $sympy/html/
tutorial.html#calculus );
2. Use embedding TeXmacs python session to run python code directly
within TeXmacs. TeXmacs will call python to run the code and show the
result. This part owns the interactive feature!
3. Moreover, TeXmacs supports flexible output formats, including pdf.

Any interesting, reference test TeXmacs file (tm format) and pdf file
from:

http://diffusion.cgu.edu.tw/ftp/TeXmacs/sympy_tut.tm (and
sympy_tut.pdf)

Hope this might have help.

cch

[Ondrej Certik]

On Thu, Feb 5, 2009 at 6:57 PM, chu-ching huang <cch...@mail.cgu.edu.tw> wrote:
>
> Just rebuild sympy-git source and test the following:
>
> from sympy import *
> a=DeferredVector('a')
> b=DeferredVector('b')
> n=10
> A=eye(11)
> a=Matrix(1,n,lambda i,j: 'a%g' %j)
> b=Matrix(1,n,lambda i,j: 'b%g' %j)
> A[0,1:]=a
> A[1:,0]=b.transpose()
> A.det()
>
> and it shows the right answer:
>
> 1 - a0*b0 - a1*b1 - a2*b2 - a3*b3 - a4*b4 - a5*b5 - a6*b6 - a7*b7 -
> a8*b8 - a9*b9
>
> Thanks all.
>
> Another suggestion is about the sympy documentation. I don't know how
> "sympy" manage the doc soruce and create the doc in html or pdf
> format.

We use sphinx -- but I think you meant that you *know* how we manage
documentation?

>
> Then I try another way to make "interactive" document of sympy as
> follows:
>
> 1. Use TeXmacs to import (or open) sympy doc ( $sympy/html/
> tutorial.html#calculus );
> 2. Use embedding TeXmacs python session to run python code directly
> within TeXmacs. TeXmacs will call python to run the code and show the
> result. This part owns the interactive feature!
> 3. Moreover, TeXmacs supports flexible output formats, including pdf.
>
> Any interesting, reference test TeXmacs file (tm format) and pdf file
> from:
>
> http://diffusion.cgu.edu.tw/ftp/TeXmacs/sympy_tut.tm (and
> sympy_tut.pdf)
>
> Hope this might have help.

Thanks for the information. Are you using the texmacs files from
data/TeXmacs/? (In our git version)
It may be useful too for you.

Ondrej