On Sat, Dec 10, 2011 at 5:46 PM, pedda <notforyou...@hmamail.com> wrote: > I noticed there is an error in the matrix, which I thought might have > prevented sympy from calculating the right values, but Mathematica > calculates this and even bigger matrices instantly. What I find > interesting though is that Maxima has the same problems with the > matrix. I have attached a new matrix from a simpler system but my > sympy is still not able to calculate this. Any ideas on the reason? > Might this have something to do with precision ? I am using a 64 bit > system if this is of any help ...
Try the latest version of sympy. The determinant of 0 is computed in a matter of a few seconds. What is disappointing is that the recent changes to try detect singular matrices don't work on this matrix: the rref form is a beautifully computed identity matrix without the zero (somewhere along the way) being detected with .is_zero. And trying to detect it by defining iszerofunc=lambda x:expand_mul(x) == 0 is still working as I write. Perhaps if a symbolic matrix is being inverted, the determinant should be computed to test for invertibility since detecting a symbolic zero for a system this size is (apparently) difficult. I can't even get the length of the string version of element 0,0 of the "inverted" matrix to print after more than a minute. How are you generating these matrices? -- 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.
