ode45 symbolic variable in odefun

Hi everybody, I would like to kindly ask for your help. My problem is following: I am trying to solve the system of ODEs, which is represented by the symbolic matrix.

1) I have this odefunction:

function [y] = myFun(~,u)
  global input
  M=input.M;
  v=input.v;
  dui = M*u+v;
end

where M is a mentioned symbolic matrix (system of ODEs), v is a vector.

2) Then I have the main script, which calls ODE solvers and plots the results.

function main()
 [t,y] = ode45(@myFun, tspan, y0, options);
 ...
end

Unfortunately, I am receiving this error: "Inputs must be floats, namely single or double."

I know, that ode45 is not designed for symbolic expressions. Of course, I tried to google it, etc., but I still cannot find the right solution. For example, I tried:

f = matlabFunction(myFun(tspan,y0))
[t,y] = ode45(f, tspan, y0, options);

but I am getting another error message: "Error using symengine>@()[-3.048662226349097;-5.801428662968666;-7.984664189221292;.....] Too many input arguments." and "Error in odearguments f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0."

Please, do you have any experience with this kind of problem? Many thanks in advance.

Answer 1

[Star Strider]

Note that your anonymous function:

@()[-3.048662226349097;-5.801428662968666;-7.984664189221292;.....]

does not accept any input arguments, so any input argument values passed to it will throw that error.

Answer 2

[Steven Lord]

Use the ODE solvers in MATLAB, like ode45, to numerically solve ODEs represented as a function handle that ode45 can evaluate to return a numeric answer.

Use the ODE solver function dsolve in Symbolic Math Toolbox to solve an ODE symbolically.