I got a way to solve the differential equation. If wrong please correct;) To solve this differential equation we must first make a variable substitution to reduce the differential equation for a first order and thus create a system of ODEs. variable change:
w1 = y w2 = y w3 = y ' Thus, deriving the above variables, we have a system of equations of the form: w1 '= w2 w2 '= f (x, w1, w2) = 4 * w2 + x desolve_system_rk4([w2, 4*w2 + x ],[w1 , w2], ics = [0,1,0],ivar = x, step = 0.1, end_points = 2) Em terça-feira, 6 de setembro de 2016 12:38:22 UTC-3, [email protected] escreveu: > > I tryed > > # w = y'' > # z = y' > > var('x, w, z') > > desolve_system_rk4( [w , 4*z + x] , [w,z] , ics = [0,1,0], ivar = x, > end_points = 10, step = 0.1) > > But does no work correty :( > > > > Em terça-feira, 6 de setembro de 2016 09:43:43 UTC-3, > [email protected] escreveu: >> >> I could not define a way to insert the arguments in RK4 command :( >> >> Em terça-feira, 6 de setembro de 2016 06:37:18 UTC-3, David Joyner >> escreveu: >>> >>> On Mon, Sep 5, 2016 at 9:33 PM, <[email protected]> wrote: >>> > How to solve ODE y'' - 4y' + y - x = 0 using rk4? :( >>> > >>> >>> >>> http://doc.sagemath.org/html/en/reference/calculus/sage/calculus/desolvers.html >>> >>> lists dsolve_rk4. >>> Was there a specific problem you encountered? >>> >>> > -- >>> > You received this message because you are subscribed to the Google >>> Groups >>> > "sage-support" 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 https://groups.google.com/group/sage-support. >>> > For more options, visit https://groups.google.com/d/optout. >>> >> -- You received this message because you are subscribed to the Google Groups "sage-support" 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 https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
