i have error in this code while using ode45
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kainat rasheed
il 23 Mag 2022
Modificato: Torsten
il 27 Mag 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]);
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
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Risposta accettata
Walter Roberson
il 23 Mag 2022
[250 :0 350]
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.
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