On Sat, Dec 10, 2011 at 10:37 AM, pedda <notforyou...@hmamail.com> wrote: > I have tried to do it non-symbolically, but I think it is rather > inelegant. I am also trying to promote the use of python/sage over the > use of Mathematica with my fellow students and it is somewhat > important to show that they can do the same thing for free with other > advantages. Since Mathematica is able to calculate the eigenvalues > without any problem or delay, it is hard to convince someone to switch > to a system that takes so much longer and is not as reliable. > > I just installed the python3 version of sympy, which didn't it done > either... You can by the way eliminate the recursion depth error by > adding sys.setrecursionlimit(2**20) to your file. So far, this is what > I found out from testing with various systems: > Sage with python 2.6: calculates up to 36x36 in a reasonable time > (65s) > python 2.7/python 3.2: calculate up to ~ 20x20 > Sage with Maxima for calculation works faster, but I have problem with > really big matrices like 400x400 ... working on it though!
Some perspective is appropriate: * Finding eigenvalues symbolically for anything for very small matrices is incredible slow and the answers you get are not going to be meaningful symbolically - you are going to want numerical answers. I am not saying sympy's algorithms couldn't be better. * 400x400 is a small matrix for numerical computations. By insisting on using a symbolic algorithm, you are making an easy problem hard. Moving to a numerical approach would allow you to handle matrices of *many* thousands of rows/columns almost instantly. * For these types of matrices you really should be using the sparse matrices in scipy.sparse. Otherwise you are wasting a ton of time storing and multiplying zeros. Cheers, Brian > -- > 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 > sympy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > -- Brian E. Granger Cal Poly State University, San Luis Obispo bgran...@calpoly.edu and elliso...@gmail.com -- 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 sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
