Hi,

I found a corner case where matrix addition does NOT
preserve matrix shape. Example:

In [13]: A = ones((0,1))

In [14]: B = ones((0,1))

In [15]: A
Out[15]: Matrix(0, 1, [])

In [16]: B
Out[16]: Matrix(0, 1, [])

In [17]: A+B
Out[17]: Matrix(0, 0, [])

While the other way round it works:

In [18]: At = ones((1,0))

In [19]: Bt = ones((1,0))

In [20]: At
Out[20]: Matrix(1, 0, [])

In [21]: Bt
Out[21]: Matrix(1, 0, [])

In [22]: At + Bt
Out[22]: Matrix(1, 0, [])

It might seem that matrices with 0 rows or columns are
some strange things. But they are not and often occur
as corner cases in more general algorithms. Hence correct
handling is indeed important.


-- Raoul

-- 
You received this message because you are subscribed to the Google Groups 
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sympy.
For more options, visit https://groups.google.com/groups/opt_out.

Reply via email to