I couldn't match the index no., can anyone please help me to resolve this issue.

clc
clear
ti = 0;
tf = 7E-5;
tp = 1E-9;
tspan= [0:1E-7:7E-5]./tp;
KC = 1;
h = 1E-2;
h1 = 1;

y0= [ (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
      (h)*rand(2,1); ((-3.14).*rand(1,1) + (3.14).*rand(1,1));
     ];

yita_mn = [0 0 0 0 0 0 
           0 1 1 1 1 0
           0 1 1 1 1 0 
           0 1 1 1 1 0 
           0 1 1 1 1 0
           0 0 0 0 0 0].*1E-3;
N = 4;
tp = 1E-9;
o = sort(10e2*rand(1,16),'ascend');
[T,Y]= ode45(@(t,y) rate_eq(t,y,yita_mn,o),tspan,y0);

Index in position 2 exceeds array bounds. Index must not exceed 6.

Error in solution>rate_eq (line 97)
dAdt(i) = dAdt(i) + yita_mn(i,j)*(At(j))*cos(Ot(j)-Ot(i));

Error in solution>@(t,y)rate_eq(t,y,yita_mn,o) (line 60)
[T,Y]= ode45(@(t,y) rate_eq(t,y,yita_mn,o),tspan,y0);

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);

figure(3)
plot(T,(Y(:,3)),'linewidth',2);
hold on
for i = 6:3:48
plot(T,(Y(:,i)),'linewidth',2);
end
grid on
hold off
xlabel("time")
ylabel("phase")
set(gca,'fontname','times New Roman','fontsize',18,'linewidth',1.8);



function dy = rate_eq(t,y,yita_mn,o)
N = 36;
dy = zeros(3*N,1);
dGdt = zeros(N,1);
dAdt = zeros(N,1);
dOdt = zeros(N,1);
P = 0.4;
a = 1;
T = 800;
tp = 1E-9;
Gt = y(1:3:3*N-2);
At = y(2:3:3*N-1);
Ot = y(3:3:3*N-0);
k = 2E-3;
for i = 1:N
    dGdt(i) = (P - (Gt(i)) - (1 + 2.*Gt(i)).*((At(i)))^2)./T ;
    dAdt(i) = Gt(i)*(At(i));
    dOdt(i) = (-a).*(Gt(i)) + o(1,i).*tp;  
    for j = 1:N
        dAdt(i) = dAdt(i) + yita_mn(i,j)*(At(j))*cos(Ot(j)-Ot(i));
        dOdt(i) = dOdt(i) + yita_mn(i,j)*((At(j)/At(i)))*sin(Ot(j)-Ot(i));
    end
end
dy(1:3:3*N-2) = dGdt;
dy(2:3:3*N-1) = dAdt;
dy(3:3:3*N-0) = dOdt;
end

Answer 1

[Torsten]

yita_mn has size 6x6, but your loop in which you access yita(i,j) runs for i = 1:16 and j = 1:16.

And dy should be allocated as dy = zeros(3*N,1), not dy = zeros(4*N,1).

[SAHIL SAHOO]

I change the code but still it's showing problem what's the cause I still can't figure out.

now loop while run for i and j for 1:36, still showing error.

[Torsten]

now loop while run for i and j for 1:36, still showing error.

Since yita_mn is 6x6, it should be obvious that each of the loops can only run from 1 to 6.

[SAHIL SAHOO]

Thanks for you comment but still I have no idea, can you please let me know how can I write this one.