Hie, Please, how do i remove the error tha arises from running this code?

    function Gain_ripples_12()
    clear all; clc;
    global P_1 P_2 B_2 B_3 B_4 delta_w_p delta_w_s delta_w_sb r gamma

      % parameters of the model
      pi= 3.143;  P_1 =1;P_2 =1 ; c = 299792458;

      lambda_1 = 1536; 
      lambda_2 = 1540;  
      lambda_0 = 1535;  
      lambda_c = (lambda_1 + lambda_2)/2;
      w_0 = (2*pi*c)/lambda_0*10^-3;
      w_1 = (2*pi*c)/lambda_1*10^-3;
      w_2 = (2*pi*c)/lambda_2*10^-3;
      w_c = (2*pi*c)/lambda_c*10^-3;
      B_3 =2.0881*10^-20;B_4 =-1.852*10^-20;
      gamma =8*10^-3;
      B_2 = B_3*(w_c - w_0)^2 + (B_4/2)*(w_c - w_0)^4;
      delta_w_p = (w_2 - w_1)/2;
      %w_sb2 = 2*delta_w_p - delta_w_s;
      r = 2*gamma*sqrt(P_1*P_2);
     % options for the ode45 
    options=odeset('RelTol',1e-4,'AbsTol',[1e-4 1e-4]); 
    % Solve the equations using 4th order Runge-Kutta
    lambda_s=1350:5:1900;
    Gs={};
    for ii=lambda_s
          w_s = (2*pi*c)./ii;
          delta_w_s = w_s - w_c;
          w_sb1 = (2.*delta_w_p - delta_w_s);
          delta_w_sb = w_c - w_sb1;
          [~,U]=ode45(@sytem,[0 1],[0 1 0 0]);
          A_sb1=U(:,1); A_s=U(:,2);
          A_1 = U(:,3); A_sb2 =U(:,4);
          G12 = abs(A_s).^2;
          Gs12= 10.*log10(G12);
          Gs{ii}=Gs12;
    end 

    % extract solution for y1 and y2
    Cunq=unique(horzcat(Gs{:}),'stable');
    EF=Cunq(1:length(lambda_s));

    %plot the solutions on the same graph
    plot(lambda_s,EF,'r')
    %legend({'$y_{1}$','$y_{2}$'},'FontSize',17,'Interpreter','latex')
    ylabel('Gain','FontSize',17,'Interpreter','latex')
    xlabel('Wavelength','FontSize',17,'Interpreter','latex')
    %title('','FontSize',17,'Interpreter','latex')
    % A function for the differential Equations
    function dz=sytem(~,A)
        % A_sb1 = A(5), A_s= A(3), A_1 =A(1), A_sb2=A(6)
    dz=zeros(4,1);
    dz(1)= 1i.*(B_2./2).*(delta_w_sb.^2 - delta_w_p.^2).*A(1) - 1i.*(B_3./6)...
        .*(delta_w_sb.^3 - delta_w_p.^3).*A(1) + 1i.*(B_4./24).*(delta_w_sb.^4 - delta_w_p.^4)...
        .* A(1) + 1i.*gamma.*P_1.*(A(1) + conj(A(2)))+1i.* r.*(A(3)+conj(A(4)));

    dz(2)=1i.*(B_2./2).*(delta_w_sb.^2 - delta_w_p.^2).*A(2) - 1i.*(B_3./6)...
        .*(delta_w_sb.^3 - delta_w_p.^3).*A(2) + 1i.*(B_4./24).*(delta_w_sb.^4 - delta_w_p.^4)...
        .* A(2) + 1i.*gamma.*P_1.*(A(2) + conj(A(1)))+1i.* r.*(A(4)+conj(A(3)));

    dz(3)=1i.*(B_2./2).*(delta_w_sb.^2 - delta_w_p.^2).*A(3) + 1i.*(B_3./6)...
        .*(delta_w_sb.^3 - delta_w_p.^3).*A(3) + 1i.*(B_4./24).*(delta_w_sb.^4 - delta_w_p.^4)...
        .* A(3) + 1i.*gamma.*P_2.*(A(3) + conj(A(4)))+1i.* r.*(A(1)+conj(A(2)));

    dz(4)=1i.*(B_2./2).*(delta_w_sb.^2 - delta_w_p.^2).*A(4) + 1i.*(B_3./6)...
        .*(delta_w_sb.^3 - delta_w_p.^3).*A(4) + 1i.*(B_4./24).*(delta_w_sb.^4 - delta_w_p.^4)...
        .* A(4) + 1i.*gamma.*P_2.*(A(4) + conj(A(3)))+1i.* r*(A(2)+conj(A(1)));

    end 
    end 
    Error using horzcat
    Dimensions of arrays being concatenated are not consistent.

    Error in Gain_ripples_12 (line 41)
    Cunq=unique(horzcat(Gs{:}),'stable');

Answer 1

[Stephan]

Hi,

there are 2 Problems in your code:

1. The Integration with ode45 leads to different lengths for the entries in GS{ii} - which causes the error. To solve this i changed:

[~,U]=ode45(@system,[0 1],[0 1 0 0],options);

to

[~,U]=ode45(@system,[0:0.0005:1],[0 1 0 0],options);

which guarantees same length of every cell in Gs.

2. The stepwide of:

lambda_s=1350:5:1900;

leads to a cell array Gs which has 4 empty entries, then one cell with results and so on, because the not adressed cells are automatically filled up by Zero entries. I used a addtionally counter variable k to solve this. Try this code in the for loop:

% Solve the equations using 4th order Runge-Kutta
lambda_s=1350:5:1900;
Gs={};
k = 1;
for ii=lambda_s
    w_s = (2*pi*c)./ii;
    delta_w_s = w_s - w_c;
    w_sb1 = (2.*delta_w_p - delta_w_s);
    delta_w_sb = w_c - w_sb1;
    [~,U]=ode45(@system,[0:0.0005:1],[0 1 0 0],options);
    A_sb1=U(:,1);
    A_s=U(:,2);
    A_1 = U(:,3); 
    A_sb2 =U(:,4);
    G12 = abs(A_s).^2;
    Gs12= 10.*log10(G12);
    Gs{k}=Gs12;
    k = k+1;
end

After making these corrections you code runs good for me and gave this result:

.

Best regards

Stephan