i have error in this code while using ode45

2 views (last 30 days)
kainat rasheed
kainat rasheed on 23 May 2022
Edited: Torsten on 27 May 2022
%constants
A=2.6e-3;
B=90;
C=0.025;
D=5.0E-3;
E=0.3;
F=0.0041;
G=0.27;
H=83.7;
%Parameter Changes
A1=2.6e-2;
B1=80;
C1=0.025;
D1=6.0E-3;
E1=1;
F1=0.008;
G1=0.27;
H1=83.7;
%hold on
f=@(t,y) [-y(2) y(1) -A(y(1)-B); C*D*(y(3)-E) -C*y(2); -G*y(3) +F*max(0,y(1)-H)];
[t,xa]=ode45(f, [0 180], [250 :0 350]);
Index exceeds the number of array elements. Index must not exceed 1.

Error in solution (line 26)
f=@(t,y) [-y(2) y(1) -A(y(1)-B); C*D*(y(3)-E) -C*y(2); -G*y(3) +F*max(0,y(1)-H)];

Error in odearguments (line 92)
f0 = ode(t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 107)
odearguments(odeIsFuncHandle,odeTreatAsMFile, solver_name, ode, tspan, y0, options, varargin);
disp(t,xa);
f=@(t,y) [-y(2) y(1) -A1(y(1)-B1); C1*D1*(y(3)-E1) -C1*y(2); -G1*y(3) +F1*max(0,y(1)-H1)];
[t,xb]=ode45(f, [0 180], [250 0 350]);
disp(t,xb);
figure(1)
plot(t,xa(:,1)+50,"LineWidth",2); ylabel("glucose(mm/dl)");
xlabel("time(min)");title('Glucose dynamics')
hold on
plot(t,xb(:,1),"LineWidth",2); ylabel("glucose(mm/dl)");
xlabel("time(min)");title('Glucose dynamics')
legend ('Orignal','Dexcom Curve')
hold off
%hold on
figure(2)
plot(t,xa(:,2)*33,"LineWidth",2); ylabel("Interstitial insulin(\uU/ml)");
xlabel("time(min)");title('Interstitial insulin dynamics')
hold on
plot(t,xb(:,2),"LineWidth",2); ylabel("Interstitial insulin(\uU/ml)");
xlabel("time(min)");title('Interstitial insulin dynamics')
legend ('Orignal','Dexcom Curve')
hold off
figure(3)
plot(t,xa(:,3)+5,"LineWidth",2); ylabel("Plasma insulin(\uU/ml)");
xlabel("time(min)");title('Plasma insulin dyanmics')
hold on
plot(t,xb(:,3),"LineWidth",2); ylabel("Plasma insulin(\uU/ml)");
xlabel("time(min)");title('Plasma insulin dyanmics')
legend ('Orignal','Dexcom Curve')
hold off

Accepted Answer

Walter Roberson
Walter Roberson on 23 May 2022
[250 :0 350]
ans = 350
Your vector of initial conditions only has one entry.
Your line of code will not be interpreted as
[250, :0, 350]
and that would be a syntax error if it was.
Likewise it is not interpreted as [250 :0: 350] -- which would give you an empty vector.
The 250 :0 part is being intepreted as (250:0) -- the vector of values starting with 250, incrementing by 1, and ending with the first number that is greater than 0... and since 250 is greater than 0, that would be the empty array.
  16 Comments

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by