Let's clean this up. I sent an email to the numpy-list asking for an advice:
http://projects.scipy.org/pipermail/numpy-discussion/2008-June/034801.html The ultimate reason that Matrix is not a subclass of a Basic is that it is mutable, while SymPy objects need to be immutable, so that when you have an expression, like (1+x)**2, you can be sure that all the instances (like "x") doesn't change in the middle of a calculation. Q: Why is a Matrix mutable? A: Because we want to play with matrices using the natural syntax: A[0,0] = x**2, etc. Q: Do we want to use Matrices in expressions? A: I think it could be very useful. Currently we can use Symbol("A", commutative=False), but it'd be nice to have an option to "attach" some matrix for it, that represents it. Also it will make the whole SymPy cleaner, if we adapt for example this approach: Make Matrix immutable, while introducing an Array class, that will behave like numpy array, be mutable etc., and a 2D array could be converted to Matrix (and back of course), thus Matrices would become regular SymPy objects. Disadvantage -- if one needs to set entries of a Matrix using the syntax "A[1, 2] = y" not only at the beginning of the calculaton, but also in the middle, then he would have to do: A = Matrix(Array(A)[1,2] = y). Of course A[1,2] = y would create an exception saying: "use the A = Matrix(Array(A)[1,2] = y)" syntax. What do you think? Ondrej --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
