Ok. I'm downloading 4.2 to see what happens, otherwise, I'll just do it by hand.
On Nov 11, 12:13 pm, David Joyner <[email protected]> wrote: > On Wed, Nov 11, 2009 at 3:10 PM, Jaasiel Ornelas <[email protected]> wrote: > > > I'm using: > > > Sage Version 4.1.1, Release Date: 2009-08-14 > > Okay. The above was done with Sage 4.2, so may or may not work in your > version. > > > > > We just started laplace in my class, so I did not know that laplace > > transforms don't solve non linear ode's. Sorry :p > > > On Nov 11, 12:01 pm, David Joyner <[email protected]> wrote: > >> On Wed, Nov 11, 2009 at 1:19 PM, Jaasiel Ornelas <[email protected]> > >> wrote: > > >> > I can't get desolve_laplace to give me a good output. I had already > >> > tried the regular solve (desolve) and it gave to told me that it > >> > cannot solve that equation. This is my code: > > >> > sage: (g,t) = var('g,t') > > >> > sage: y=function('y',t) > > >> > sage: DEiii = pi * (39/100*y + 1/2)^2* diff(y,t) + a * sqrt(2*g*y) > > >> This is a non-linear ODE. You can't use Laplace transforms > >> to solve such ODEs. > > >> However, it is separable and I can solve a slightly simpler version: > > >> sage: t = var("t") > >> sage: y = function("y",t) > >> sage: DE = y^2*diff(y,t)+sqrt(y)==0 > >> sage: desolve(DE,[y,t]) > >> -2/5*y(t)^(5/2) == c + t > > >> Which version of Sage are you using? > > >> > sage: a = .5^2*pi > > >> > sage: DEiii > > >> > 1/10000*(39*y(t) + 50)^2*pi*D[0](y)(t) + 0.250000000000000*pi*sqrt(g*y > >> > (t))*sqrt(2) > > >> > sage: desolve(DEiii, [y,t]) > >> > Traceback (most recent call last): > >> > ... > >> > NotImplementedError: Maxima was unable to solve this system. > > >> > sage: desolve_laplace(DEiii, ["t","y"], [0,50,0]) > >> > "?%ilt(-(1521*'laplace('y(t)^2*'diff('y(t),t,1),t,false)+3900*'laplace > >> > ('y(t)*'diff('y(t),t,1),t,false)+2500*sqrt(2)*'laplace(sqrt(g*'y > >> > (t)),t,false)-125000)/(2500*false),false,t)" > > >> > Perhaps it's because I can't understand the output, but if anyone > >> > could help me with this, thank you. --~--~---------~--~----~------------~-------~--~----~ 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/sage-support URL: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
