Matlab Meshgrid color map plotting

Lin Qiao

2016 9 28

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更新时间：2016 9 29

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This seems like a long question, but I do believe it's a simple one... I am a matlab beginner and I urgently need to solve it for the project I'm working on...So I would really appreciate if someone could help me

I successfully used meshgrid to plot a color-map I needed for my project, with following codes:

Creating meshgrid first:

    [x1,z1] = meshgrid(0:1:600,300:1:600);
    [x2,z2] = meshgrid(0:1:600,0:1:300);

Then just some constants defined:

    n1 = 1.0;
    n2 = 1.5;
    lambda = 100;                         % wavelength is 600 nm
    k0 = (2*pi)/lambda;                    % freespace wavenumber
    ti = 30*pi/180;                        % angle of incident, t1 in Brewster function
    kxi = n1*k0*sin(ti);                       % x component of the incident wavevector
    kzi = -n1*k0*cos(ti);                      % z component of the incident wavevector
    kxr = kxi;                              % x component of the reflected wavevector
    kzr = -kzi;                             % z component of the reflected wavevector
    Rs = (kzi-kzt)/(kzi+kzt);

Now Eureal is the function I want to plot, with x1 and z1 as its coordinate:

    Ei = cos(kxi.*x1 + kzi.*z1)+ sin(kxi.*x1 + kzi.*z1).*1i;     %incident E_field use upper x and z
    Er = Rs.*(cos(kxr.*x1 + kzr.*z1)+ sin(kxr.*x1 + kzr.*z1).*1i);     %reflected E_field
    Eu = Er + Ei;                                                  %Uper E_field
    Eureal = real(Eu);
    figure;
    surf(x1,z1,Eureal,'EdgeColor','None');
    view(2);
    xlabel('x','fontsize',20);
    ylabel('z','fontsize',20);
    colormap jet;

My problem is, I needed a different way of coding, because later on it will involves matrix calculation, but this way of coding doesn't produce the right graph like it did in the first method so the different way I used is as follow:

[x,z] = meshgrid(0:5:600,0:5:600);

Then still the same constants as above, so I will not type down

Now here is what's different:

    Ei = zeros(size(x));
    Er = zeros(size(x));
    for z1 = 80:mm(1)
        for x1 = 1:mm(1)
            Ei(z1,x1) = cos(kxi.*x(x1) + kzi.*z(z1))+ sin(kxi.*x(x1) + kzi.*z(z1)).*1i;%exp(-1i*kzia*z(z1))*exp(-1i*kxia*x(x1));    % ETazi*exp(-1i*kxia*x(x1))
            Er(z1,x1) = Rs.*(cos(kxr.*x(x1) + kzr.*z(z1))+ sin(kxr.*x(x1) + kzr.*z(z1)).*1i); %exp(-1i*kzra*z(z1))*exp(-1i*kxra*x(x1)); % ETazout*exp(-1i*kxia*x(x1))
            Eu = Er + Ei;                                                  %Uper E_field
            Eureal = real(Eu);
            Eplot = zeros(size(x)) + Eureal;
        end
    end  
    figure
    surf(x,z,Eplot,'EdgeColor','None');
    view(2);
    xlabel('x','fontsize',20);
    ylabel('z','fontsize',20);
    colormap jet;

I don't know what is the reason that the second method is problematic, and I need the for loops and x(x1), z(z1) indexing for coding later on when it involves matrix, because then the first method won't work...

So could anyone help me?