ptr_mplprims.mwHello,I am trying solve  a travelling force problem with pdsolve, but I cannot obtain the second derivative of the solution. I obtained the first derivative, with help from another post (http://www.mapleprimes.com/questions/80997-Derivative-From-Numeric-PDE-Soln#comment81512). When I tried doing the same thing for the second derivative it didn't work. Any sugestions would be helpful. Thank you!!!

HI,is it possible to solve the ODE system (that I have uploaded) by adding events at a certain timestep, instead of reformulating the system for each step.The ODE system expresses two coupled movements y(t) and X(t). The current position of y(t) is controlled by a parameter which depends on values calculated in the previous step, while changing the sign for each step.Thank you! 

Hello, I'm currently trying to solve this set of ODE's, but the way I have formulated the problem seems to be hard to process. Is there any simpler way of doing this, because it takes Maple a few minutes to solve 10 steps and I need more than a 100.Thank you in advance!l := 1.34*.75;Omega[p] := sqrt(g/l);v := .75;f[p] := .35*v^3-1.59*v^2+2.93*v;bmin := 0.157e-1;ci0 := y1(0) = 0, (D(y1))(0) = v;u0 := 0+v/Omega[p]+(-1)^0*bmin;p1 := diff(y1(t), t, t)+Omega[p]^2*(u0-y1(t)) = 0;k[1...