In pull request 1015 <https://github.com/sympy/sympy/pull/1015> you can do
this with the following code
In [1]: A = MatrixSymbol('a', 3, 3)
In [2]: print A.as_explicit()
[a(0, 0), a(0, 1), a(0, 2)]
[a(1, 0), a(1, 1), a(1, 2)]
[a(2, 0), a(2, 1), a(2, 2)]
Each of these entries are a unique symbol (actually a function object).
You can also just ask for A[1,2] and get a(1, 2) without the as_explicit
call and it'll generate it on the fly.
In [3]: A[1,2]
Out[3]: a(1, 2)
Unfortunately this is not the same text as you're looking for.
A simpler and probably better solution that works in master is to use a
doubly nested list comprehension. I apologize for the horizontal coding.
This is effectively just a doubly nested for loop written sideways.
In [4]: [[Symbol('a_%d%d'%(i,j)) for j in range(3)] for i in range(3)]
Out[4]: [[a₀₀, a₀₁, a₀₂], [a₁₀, a₁₁, a₁₂], [a₂₀, a₂₁, a₂₂]]
-Matt
On Sun, Feb 5, 2012 at 11:54 AM, Comer <comer.dun...@gmail.com> wrote:
> I am working on a project which requires that I create a matrix of
> symbols. For discussion purposes say the matrix is 3 x 3. The matrix
> is to contain 9 unique symbols and my preferred format is the usual
> matrix format:
>
> a11, ..., a33 = symbols('a_11 ....a_33')
>
> Now obviously I could easily just type in the above for all nine
> symbols. However, what I want to see how to do is to create a 3 x 3
> array as above but do it in a couple of for loops. I looked at the
> symbols() function but it only seems to work with a linear sequence of
> symbol names such as x0, x1, x2, .... xN. But I can not see how to do
> the same for a 2d array of symbol names such as x00, x01, x02, ... .
> It would be convenient in my project to be able to quickly create the
> 2d array of symbols directly by calling symbols(). It would save some
> typing.
>
> Can someone please let me know how best to do this?
>
> Thanks.
>
> Comer
>
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