"Inputs must be floats, namely single or double"

system of equations is:

F = @(t, r, y) [y(1), y(2), y(3), f_integral]

And then calling the ode solver:

[t, y] = ode45(F, [0 5], [1 1 1]).

[Torsten]

Please show the differential equation you are trying to solve in a mathematical notation.

From the question you deleted meanwhile, it was not clear what you were trying to solve (at least for me).

Best wishes

Torsten.

Answer 1

[Torsten]

function main
tspan=[0 5];
y0=[1; 1; 1; 0];
[t,y]=ode45(@fun,tspan,y0)

function dy=fun(t,y)
dy=zeros(4,1);
dy(1)=y(1);
dy(2)=y(2);
dy(3)=y(3);
funint=@(r)(y(3)^2+y(4)^2)*r;
dy(4)=integral(funint,-1,1);

Best wishes

Torsten.

[Torsten]

r is just a formal integration variable - it's not needed in the parameter list for "fun".

Best wishes

Torsten.