I fixed the naming thing at https://github.com/sympy/sympy/pull/2471.
The other thing looks like another bug.
And I guess you are right. There should be a faster determinant method
for this special case. It will still have to take a little time to
expand the polynomial, but it shouldn't be that slow.
Aaron Meurer
On Sat, Sep 21, 2013 at 1:25 AM, Pablo Puente <ppue...@googlemail.com> wrote:
> Hi Aaron,
>
> Thanks for the hints.
>
> I tried Matrix.det() with methods "berkowitz", "bareis" an "det_LU"
> (docstring
> "lu_decomposition" method is wrong) and still takes forever.
> "lu_decomposition" takes 1 minute, but still it is too much for a diagonal
> matrix.
>
> I also tried using SparseMatrix.eigenvals() with no improvements:
> M=(2-x)*SparseMatrix.eye(100)
> M.eigenvals()
>
> I tried with SparseMatrix.det() with different methods and I get the error:
> S=(2-x-y)*SparseMatrix.eye(100)
> S.det()
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/home/pape/sympy/sympy/matrices/matrices.py", line 2435, in det
> return self.det_bareis()
> File "/home/pape/sympy/sympy/matrices/matrices.py", line 2501, in
> det_bareis
> M[i, j] = cancel(D)
> File "/home/pape/sympy/sympy/matrices/immutable.py", line 64, in
> __setitem__
> raise TypeError("Cannot set values of ImmutableMatrix")
> TypeError: Cannot set values of ImmutableMatrix
>
>
> On Friday, September 20, 2013 9:25:01 PM UTC+2, Pablo Puente wrote:
>>
>> While writing Wester test P22 I see calculating the eigenvalues of a
>> diagonal matrix of dimension 100 takes forever:
>>
>> M=(2-x)*eye(100);
>>
>> assert M.eigenvals() == {-x + 2: 100}
>>
>>
>> I see that M.det() also takes forever.
>>
>> Maybe Matrix.det() could use a special implementation for big diagonal
>> matrices?
>>
>> Best Regards
>> Pablo
>
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