How can I plot a graph by varying two parameters a and b in system of ODE at the same time?
6 views (last 30 days)
Show older comments
How can I plot a graph by varying two parameters say a and b in the system of ordinary differential equations given below at the same time so that the first line of solution will be when a=1, b=2, the second line of solution will be when a=2, b=3, the third line of solution will be when a=3, b=4 and I will have three lines of solutions on the same graph? I want to plot t against ![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1627218/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1627218/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1627263/image.png)
function SYSTEM1ODE ()
global C a b d e g
clear all
clc
tspan=[0 5];
a=1;d=2;C=10000;e=5;g=1;
for b= 2:1:4
[t,x]=ode45(@modmat, tspan, [1200;1150;1000])
plot(t,x(:,2),'linewidth',1.5)
xlabel('Time (Days)'),ylabel('Amonut (X_2)')
hold on
end
function xprime = modmat(t,x)
xprime=[0;0;0];
xprime(1)=C-a*x(1)-b*x(2)+d*x(1);
xprime(2)=a*x(1)-b*x(2)-(d+e)*x(2);
xprime(3)=e*x(2)-g*x(3);
end
end
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1627268/image.png)
How can I add 'a' to it, so that 'a' and 'b' will be varying at the same time and still get three lines of solutions on the same graph?
2 Comments
Torsten
on 25 Feb 2024
Can you include the code for a single combination ? We will show you how to make a loop to use it three times.
Accepted Answer
Torsten
on 26 Feb 2024
Edited: Torsten
on 26 Feb 2024
A = [1;2;3];
B = [2;3;4];
C = 10000;
d = 2;
e = 5;
g = 1;
tspan = [0 5];
for i = 1:numel(A)
a = A(i);
b = B(i);
[t,x] = ode45(@(t,x)modmat(t,x,a,b,C,d,e,g),tspan,[1200;1150;1000]);
plot(t,x(:,2),'linewidth',1.5)
xlabel('Time (Days)'),ylabel('Amonut (X_2)')
hold on
end
function xprime = modmat(t,x,a,b,C,d,e,g)
xprime=[0;0;0];
xprime(1)=C-a*x(1)-b*x(2)+d*x(1);
xprime(2)=a*x(1)+b*x(2)-(d+e)*x(2);
xprime(3)=e*x(2)-g*x(3);
end
More Answers (0)
See Also
Categories
Find more on Ordinary Differential Equations in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!