MATLAB: Solve ODE for variable domain

ode systemvariable domain

Hi all

is it possible to solve the same ODE system for 3 adiacent different domain? Do i need something like that?

if x>x1&&x<=x2
  .
  .
  .
elseif x>=x2&&x<x3
    .
    .
    .
elseif x>x3
    .
    .
    .
end

how continuity will be preserved?

Thank you for the help

Regards

Best Answer

So you would then call your ode with something like:

[x,Y] = ode45(@nozzlesinglebobb, xspan, Y0,[],xstartconica,xfineconica,Ralfa_end,Rbeta_end,alfa_end_rad,beta_end_rad,xc_end,yc_end,Lnozzle_end,raggio_end,f1,f2,f3);

where xspan = [0 x_final] and Y0 = [Pt0; M0] or similar.

Then

Pt = Y(:,1);
M = Y(:,2);

Related Solutions

MATLAB: Ode Not enough input arguments.

As the error states, you are not calling the function nozzlesinglebobbgola with enough input arguments:

nozzlesinglebobbgola(x, Ynozzle, xstartconica,xfineconica,Ralfa_end,Rbeta_end,alfa_end_rad,beta_end_rad,xc_end,yc_end,Lnozzle_end,raggio_end,f2)       % how you call it

nozzlesinglebobbgola(x, Ynozzle, xstartconica,xfineconica,Ralfa_end,Rbeta_end,alfa_end_rad,beta_end_rad,xc_end,yc_end,Lnozzle_end,raggio_end,f3,f2,f1) % how you defined it

Or with the intermediate variables removed for clarity:

nozzlesinglebobbgola(x, Ynozzle, .. ,raggio_end,f2)       % how you call it
nozzlesinglebobbgola(x, Ynozzle, .. ,raggio_end,f3,f2,f1) % how you defined it

Using so many positional input arguments is buggy (e.g. like this question) and makes the code very difficult to understand. Avoid doing this. I strongly recommend that you do either of these:

put all of those parameters into one scalar structure and pass that.
use a nested function, then you don't need those input arguments at all (nor the anonymous function).

https://www.mathworks.com/help/matlab/math/parameterizing-functions.html

MATLAB: ODE system with variable parameter, Boundary conditions and domain

This could be done something like this:

Dall = {0:0.1:1,0:0.1:2}; % however many domains you need etc
Y0 = {[Tt01;Pt01;M01],[Tt02;Pt02;M02],[Tt03;Pt03;M03]};
for iDom = 1:numel(Dall)
    xRange = Dall{iDom};
    for iInitial = 1:numel(Y0)
        [xSol{iDom,Iinitial},YSol{iDom,Iinitial}]=ode23(@chambsinglebobb,xRange,Y0{iInitial});
    end
end

HTH

Best Answer

Related Solutions

MATLAB: Ode Not enough input arguments.

MATLAB: ODE system with variable parameter, Boundary conditions and domain

Related Question