matlab ode23 extract changing parameter of successful integration steps - matlab

Question

I have a system of coupled differential equations. One of the parameters is changing over time and I would like to track the change of said parameter (and overlay it with my final graph).
I tried to write all generated values of v into a separate vector. However, since not all function calls result in a successful integration I end up with many values for v than of my ode-solver return vector.
Can someone point out how I could implement this feature into my code?
Thanks so much, been trying this for a couple of hours now. To no avail, unfortunately.
Cheers,
dahlai
Find my code below:
Coupled differential equations + attempt of writing all values of v to vector:
%chemostat model, based on:
%DCc=-v0*Cc/V + umax*Cs*Cc/(Ks+Cs)-rd
%Dcs=(v0/V)*(Cs0-Cs) - Cc*(Ys*umax*Cs/(Ks+Cs)-m)
function dydt=systemEquationsRibose(t,y,funV0Ribose,V,umax,Ks,rd,Cs0,Ys,m)
v=funV0Ribose(t,y); %funV0Ribose determines v dependent on y(1)
y(2) = max(0, y(2)); %minimum value of y(2), therefore Cs, is 0
dydt=[-(v/V)*y(1)+(umax*y(1)*y(2))/(Ks+y(2))-rd;
(v/V)*(Cs0-y(2))-((1/Ys)*(umax*y(2)*y(1))/(Ks+y(2)));
];
% persistent k
% persistent vel
%
% if isempty(vel)
% vel=0
% end
%
% if isempty(k)
% k=1
% end
%
% if v>= vel(k)
% vel(k+1)=v %stores all v values, for plotting and analysis of v0 behaviour
% end
% assignin('base','vel',vel)
% k=k+1
end
ode23-solver call:
[t,y]=ode23(#systemEquationsRibose, [t0 tx],[Cc0 Cs0],[],#funV0Ribose,V,umax,Ks,rd,Cs0,Ys,m);
v is given by a separate function called funV0Ribose.The value of funV0Ribose is dependent on y(1) at every given time point.

Answer 1

Doing some more digging (and putting the right words into google) I found a solution:
Second answer of together with reading through the documentation (which is still very hard for me, since I am pretty new to MATLAB):
Saving derivative values in ode45 in Matlab
My implementation:
Initializing the output function:
options=odeset('OutputFcn', #recordFun)
global v
if isempty(v)
v=0
end
Calling ode-solver:
[t,y]=ode23(#systemEquationsRibose, [t0 tx],[Cc0 Cs0],options,#funV0Ribose,V,umax,Ks,rd,Cs0,Ys,m);
recordFun:
function status=recordFun(t,y,flag,funV0Ribose,V,umax,Ks,rd,Cs0,Ys,m)
status = 0; %=0 to keep ode-solver running, if =1 ode-solver stops
%counter for growing vectors
persistent k
if isempty(k)
k=0
end
%recording of every v value
persistent vel %to store vel for multiple calls of recordFun
global v %to access v from #systemEquationsRibose
vel(k+1)=v
assignin('base','vel',vel)
k=k+1 %counter increase for next elements of growing vectors
end