On Tue, Jul 7, 2009 at 9:35 AM, Priit Laes<plaes...@gmail.com> wrote: > > Ühel kenal päeval, T, 2009-07-07 kell 00:03, kirjutas Ondrej Certik: >> On Mon, Jul 6, 2009 at 1:47 PM, Priit Laes<plaes...@gmail.com> wrote: >> > >> > Hey! >> > >> > While trying to implement method of characteristics, I ran into a >> > following problem: >> > >> > I get (choose) following system of characteristic equations as a >> > solution for PDE [ D(u(x, t), t) + a*D(u(x, t), x) == 0 ]: >> > >> > dx/ds = a ; dt/ds = 1 ; dz/ds = 0 >> > >> > Now, after solving these equations I have a system of three equations, >> > from where I have to eliminate the parameter s: >> > x(s) = a*z+C1 ; t(s) = s + C2 ; z(s) = C3 >> > C1, C2, C3 are arbitrary constants... >> > >> > And finally present the solution as z(x, t) = ... >> > >> > How can I achieve this using only sympy? :P >> >> How would you do it mathematically? >> >> Let's take this example as a start: >> >> http://en.wikipedia.org/wiki/Method_of_characteristics#Example >> >> If I understand it correctly, the solution is given by F(z, x(s), >> t(s)) = 0. Do you know how to write this equation using sympy? If not, >> let me research how to do it, I was learning that just last semester, >> but I forgot already, all I remember is that there is quite a direct >> way to do that, as long as one can solve the equations. > > I got something finally working now > > Just pull pde-wip branch again...
I played with it, I think it looks good. Could you please add more tests for it? I think currently there are only 2. Thanks for the work, Ondrej --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
