Let's clean up this code a bit:
clc;
%clear all; % <--- This is a bad habit. Do you reboot your computer every
%time you run this script? Of course you don't. Then don't use this. At
%most you'll need clearvars.
n = 20;
x=accumarray([2 3 n-1 n]',1);
% This is a very strange way to do this (especially without a comment)
% This is a lot clearer:
x=zeros(n,1);x([2 3 end-1 end])=1;
B = toeplitz(x,x);
numEdgesToRewire = 2;
matrixSize=20; % Should this perhaps be matrixSize=size(B,1);? Or n?
edgesToRewire = randperm(matrixSize, numEdgesToRewire);
for n = 1:numEdgesToRewire % use n as loop index
node1 = edgesToRewire(n);
% node2 = randi([1, matrixSize]);
node2 = node1; % this will already enter the loop
while node2 == node1 || B(node1, node2) == 1
node2 = randi([1, matrixSize]);
end
B(node1, node2) = 1;
B(node2, node1) = 1;
end
disp(B)
theta = 0.3;
dh = 2^-9;
dp = 2^-7;
phi = 3;
ita = 1;
% y=[x(1);x(2);x(3);x(4);x(5);x(6);x(7);x(8);x(9);x(10);x(11);x(12);x(13);x(14);x(15);x(16);x(18);x(19);x(20)]
% This is not a matlab way to do it. Use indexing instead:
y = x(setdiff(1:end,17)); % did you indeed want to remove element 17?
x0 = rand(1,20);
% i = 1; % you aren't using i in your code
% f = []; % you aren't using f in your code
% [t,x]=ode45(@(kau(t, x, B),tspan, x0);
% After resolving the syntax errors, you will need to define two variables:
tspan =
x0 =
[t,x]=ode45(@kau,tspan, x0);
%H=x(1)+x(3)+x(5)+x(7)+x(9)+x(11)+x(13)+x(15)+x(17)+x(19);
%P=x(2)+x(4)+x(6)+x(8)+x(10)+x(12)+x(14)+x(16)+x(18)+x(20);
% again; use indexing
H = x(1:2:end);
P = x(2:2:end)
plot(t, H, 'b');
hold on
plot(t, P, 'r');
hold off
function xprime = kau(t, x, B)
nn = length(x);
while i <= nn
f = [f; x(i)*(1 - theta*x(i)) - x(i+1) - (x(i)*x(i+1)) / (1 + x(i+1)); ...
(phi*x(i)*x(i+1)) / (1 + x(i+1)) - ita*x(i+1)];
i = i + 1;
end
xprime = f+B*y;
end
