Ondrej Certik wrote: > I just discovered we probably need to think about this: > > In [1]: a = Matrix((1, x), (2, y)) > > In [2]: from numpy import array > > In [3]: a > Out[3]: > ⎡1 x⎤ > ⎣2 y⎦ > > In [4]: Matrix(sin(array(a))) > Out[4]: > ⎡sin(1) sin(x)⎤ > ⎣sin(2) sin(y)⎦ > > In [5]: sin(a) > [...] > > AttributeError: 'Matrix' object has no attribute 'is_Number' > > > What should [5] return? The same as [4] or the sin of a Matrix, which > is defined as sin(A) = Q*sin(D)*Q^T if A = Q*D*Q^T and D is > diagonal, so sin(D) is just the D with sin applied to the diagonal > terms.
This stuff generates neverending discussions on numpy lists. Numpy currently solves this by having array (n-dimensional container) and matrix (special 2d array w.r.t. multiplication and some functions). As Matrix in SymPy is a linear algebra matrix, it should IMHO behave as such, i.e. sin(A) = Q*sin(D)*Q^T. Then maybe an Array would be usefull, something like sympy version of list of lists [of lists...]. r. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sympy?hl=en -~----------~----~----~----~------~----~------~--~---
