On Tue, May 27, 2008 at 2:22 PM, astozzia <[EMAIL PROTECTED]> wrote: > > > > On May 26, 1:50 pm, Friedrich Hagedorn <[EMAIL PROTECTED]> wrote: > >> >> The problem is that >> >> In [26]: type(dvec) >> Out[26]: <type 'list'> >> >> so you have to convert your 'vector' to a sympy >> >> In [27]: mdvec=Matrix(dvec).T > > great this works perfectly! I redid my definitions of the vectors and > I simply defined dvec=diff(vec,t) and dvecM=Matrix(dvec).T > > >> In [31]: mdvec*(1/x**2) >> Out[31]: >> ⎡ d d d ⎤ >> ⎢-sin(φ(t))*──(φ(t)) ──(x(t)) ──(z(t))⎥ >> ⎢ dt dt dt ⎥ >> ⎢─────────────────── ──────── ────────⎥ >> ⎢ 2 2 2 ⎥ >> ⎣ x x x ⎦ >> >> (subs the x**2 by your sqrt(...)) >> >> The In[31] must be so unconvenient because otherwise the '/' fails. >> It seems to be a bug. > > I didn't have this problem though: > I simply defined the unit vector along 'dvec' by: > > evec=dvecM/sqrt(s.dot(dvec,dvec)) > > Note that I had to use the 'Matrix' and divide my the norm of the > 'list'. Kinda weird...
Excellent. If you think you know some particular things that you know how to improve in the sympy interface, please let us know, either with or without a patch (both is very welcome). Ondrej --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
