Ondrej
Thank you for the tip to use the subs function, I was expecting it to exist but I had trouble finding it. I will be working with 2-d arrays. Which 2d formats play well with both the subs and the diff funtions? It seems that Matrix lacks the diff attribute , list and numpy.array lack the subs attribute. Is there a better way to handle this than a lot of Matrix(diff(Matrix(rdotarray).subs(xdot,s)[:],s)).subs(s,xdot) ? Where in the Docs am I most likely to find the answers to my question? I am using sympy 6.2 now. Thanks again Scott diff((z*zdot).subs(xdot, s), s) On Oct 18, 11:34 am, Scott <[EMAIL PROTECTED]> wrote: > What is the sympy translation of the following Mathematica syntax? > When I try to code this in sage or sympy xdot and zdot remain as a > diff object and I cannot us them in symbolic manifulations. My sympy > version is 5.15 (ubuntu 8.10) or whatever is embedded in sage 3.1.2. > > V/R > > Scott > > x=q[t]; > z=1/2 *x^2; > xdot=D[x,t]; > zdot=D[z,t]; > D[z*zdot,xdot] > > out: 1/2 q[t]^3 --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
