comp.soft-sys.matlab - The MathWorks calculation and visualization package.
Dear Matlab users, Does anyone know how to solve the following ODE numerically in Matlab? u(x)*(du/dx) = -p(x) -D*u(x)^2 with the boundary condition u(infinity)=1 and p(x) known. I have tried bvp4c, but without success. I don't know what to do with the u(x)*(du/dx) term. One can solve the equation analytically but I must solve some parts numerically anyway, so I thought I could solve the whole thing numerically. Regards Daniel Soderstrom
Hello, I would plot this nonlinear differential equation : RC * dy/dt + y(t) = x(t); x(t) = sin(wt); If I consider R=cste there is non problem and I can plot the solution quickly but in reality I would have : R = 1 / ( x(t) * ( 1-exp( -sqrt(x(t)) ) ) / sqrt(x(t) ) Matlab can't solve it, it run and never finish the calcul. Even if I use a simple form for R=1/(x(t) * 0.9); Someone could tell me how to solve this equation ? thanks PS : this is what I've done : I've use the ode45 solver %In Matlab tspan = [1e-9 1e-6]; y0 = 0; [t, y] = ode45('dydt',tspan,y0); plot(t, y); %%% The function I've define in a dydt.m file function dydt = dydt(t, y) w=2*pi*1e6; x = sin(wt); C = 10e-15; R = 1 / (0.9*x(t)); dydt = 1/(R*C) * (x - y); %end of function
Hello all, In the documentation of the Matlab PDE Toolbox, the problems that can be solved by using PDE are described as 2nd order PDE problems, i.e. elliptic parabolic problems. I have a 1st order PDE problem with one spatial dimension and time variable. Can I solve that problem with PDE toolbox as well. Specifically my problem is solving the equations of unsteady flow of a gas inside a tube. Therefore, I also have two time and distance dependent temperatures, namely gas temperature and wall temperature. Thanks in advance Sahina
I have a set of points (x_1,y_1),(x_2,y_2)...(x_n,y_n) I am trying to find a "cubic spline" 'interpolating' (passing thru) these points. It should start from the first point and stop at the last point. Is there a fast way to do this in matlab? I looked at the spline toolbox but most examples there are for single valued functions. Thanks, --j