Hi, On Fri, Jul 10, 2015 at 7:30 AM, 刘金国 <[email protected]> wrote: > 4 x 4 is needed ~~ > mathematica runs extremely fast for 4 x 4 matrix as it should be, but ...
Can you post the Mathematica result? So that we know what you are trying to get and we can then help you get it with SymPy. Ondrej > > 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 [email protected]. > To post to this group, send email to [email protected]. > 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. -- 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 [email protected]. To post to this group, send email to [email protected]. 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/CADDwiVCdnS06PgmkJ1jLx9LvV1KS2Cg%3DOy6%2BvcWcaus4O_oYFw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
