Hi, On Jun 1, 8:51 am, Brian Granger <[email protected]> wrote: > Hi, > > In sympy.physics.quantum we use sympy Matrix instances all over the > place. These can be quite large (100x100 up to many 1000x1000. In > the future we could get even bigger) and always have symbolic entries. > At times we do like to convert them to numerical numpy arrays, but in > many cases we really want the symbolic forms. >
Could you tell what the densities of those large matrices are ? It is defined by (number of non-zeros)/(N**2). Also, it would be great if you could post a few such matrices that you use. Or direct me to pieces of code which generate the matrices that you use. > > > > > > > > > On Sat, May 28, 2011 at 6:56 AM, SherjilOzair <[email protected]> wrote: > > I would like to know how and where Sympy's matrices are used. > > Is Sympy matrices used for numeric computing anywhere ? > > Are Sympy Matrices expected to offer any advantage that matrices in > > numpy/scipy or other libraries cannot offer ? > > > Is its use limited to symbolic ? What size of Matrices with symbolic > > content is used ? > > Operations on Expr are way costlier than operations on numerics. So, > > knowing the size of the symbolic matrices that are required would help > > me in optimization when writing algorithms for sparse matrices, and > > also when refactoring Matrix. > > > I expect that one cannot use too large symbolic matrices, as solving/ > > inversing/etc. would result in expression blowup. > > > I would be glad if you could also tell what running time you would > > expect from the matrices that you use. > > instant ;) > > When we are dealing with large symbolic matrices, we are typically > just doing matrix/vector multplies. But for small matrices we do > other things like linear solves, decompositions and eigenvalue > problems. symbolic eigenvalues are great, but expressions quickly get > out of hand as the matrix size increases. > Do you require to solve eigenvalue problems of matrices bigger than 4*4 ? How are you doing it currently ? Matrix.diagonalize only works for matrices smaller than 5*5, as polys.roots can only solve degree 4 equations and less. > Cheers, > > Brian > > > -- > > You received this message because you are subscribed to the Google Groups > > "sympy" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > For more options, visit this group > > athttp://groups.google.com/group/sympy?hl=en. > > -- > Brian E. Granger > Cal Poly State University, San Luis Obispo > [email protected] and [email protected] -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. 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.
