4 x 4 is needed ~~ mathematica runs extremely fast for 4 x 4 matrix as it should be, but ...
在 2014年2月12日星期三 UTC+8上午5:40:19，Vinzent Steinberg写道： > > On Monday, February 10, 2014 11:27:09 PM UTC-5, monde wilson wrote: >> >> why eigenvectors very slow >> >> what is the difference between numpy and sympy when doing matrix >> calculation >> > > Sympy calculates eigenvectors symbolically (thus exactly), numpy > calculates them numerically using floating point arithmetic. > In general you don't want to use sympy to calculate the eigenvectors for > matrices larger than 2x2, because the symbolic results can be very > complicated. (IIRC, the eigenvalues are calculated by finding roots of the > characteristic polynomial, which can lead to nasty expressions for > dimension 3 and beyond.) > > >> will numpy faster and more accurately >> > > Numpy will be a lot faster, but not more accurate. If you only need > numerical results, you probably should use numpy for this. > > Vinzent > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/62a17328-bcd2-4955-9534-ae5358e89041%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
