How can i use this vector in my ODE function?

I have a vector of infusion rate values that i want to use in a differential equation. The infusion rates are given by this:

tspan = [0,60];

time_vals = 0:1:tspan(end);

SNP_infratevals = zeros(size(tspan));

for i = 1:length(time_vals)

if time_vals(i) > 0 && time_vals(i) <= 10

SNP_infratevals(i) = 30;

elseif time_vals(i) > 10 && time_vals(i) <= 20

SNP_infratevals(i) = 20;

elseif time_vals(i) > 20 && time_vals(i) <= 25

SNP_infratevals(i) = 6*(time_vals(i)-20)+20; % function

elseif time_vals(i) > 25 && time_vals(i) <= 35

SNP_infratevals(i) = 50;

elseif time_vals(i) > 35 && time_vals(i) <= 45

SNP_infratevals(i) = -4*(time_vals(i)-35)+50; % function

elseif time_vals(i) > 45 && time_vals(i) <= 50

SNP_infratevals(i) = 10;

elseif time_vals(i) > 50 && time_vals(i) <= tspan(end)

SNP_infratevals(i) = 25;

end

end

and i want to use it in my function : CVODE(t, y, SNP_infusion) as "u" in the line: dx2dt = 1/tau2 * (u-x2-(alpha*x3));

Do I need to interpolate maybe? If so how?

Answer 1

[Torsten]

Integrate from t=0 to t=10 and use u = 30.

Restart the ode solver with the solution at t = 10 and integrate from t=10 to t = 20 with u = 20.

Restart the ode solver with the solution at t = 20 and integrate from t=20 to t = 25 with u = 6*(t-20)+20.

...