Program wont show plot

Hello, my program wont show a plot when i run my code, only an empty figure box. Can someone help?

 n0 = 1;                                         %air
 n1 = 1.4;                                       %layer 1
 n2 = 2;                                         %layer 2
 n3 = 3.5;                                       %silicon

 L0 = 650*10^(-9);                               %centre wavelength
 L1 = 200*10^(-9): 5*10^(-9): 2200*10^(-9);      %lambda from 200nm to 2200nm

 x = ((pi./2).*(L0./L1));                        %layer phase thickness

 r01 = ((n0 - n1)./(n0 + n1));                   %reflection coefficient 01
 r12 = ((n1 - n2)./(n1 + n2));                   %reflection coefficient 12
 r23 = ((n2 - n3)./(n2 + n3));                   %reflection coefficient 23

 t01 = ((2.*n0)./(n0 + n1));                     %transmission coefficient 01
 t12 = ((2.*n1)./(n1 + n2));                     %transmission coefficient 12
 t23 = ((2.*n2)./(n2 + n3));                     %transmission coefficient 23

 Q1 = [1 r01; r01 1];                            %Matrix Q1
 Q2 = [1 r12; r12 1];                            %Matrix Q2
 Q3 = [1 r23; r23 1];                            %Matrix Q3

 for i = 1:length(x)

    P = [exp(j.*x(i)) 0; 0 exp(-j.*x(i))];          %General Matrix P

    T = ((1./(t01.*t12.*t23)).*(Q1*P*Q2*P*Q3));     %Transmission

    T11 = T(1,1);                                   %T11 value
    T21 = T(2,1);                                   %T21 value

    R = ((abs(T21./T11))^2).*100;                    %Percent reflectivity

    plot(L1,R)

 end

Answer 1

[Walter Roberson]

You are only plotting one point at a time, and you did not specify a marker. When you plot() the default is to not display a marker. Also, each time you plot you overwrite everything you have plotted before.

You need to change to

      plot(L1, R, '*')
      hold on

[Steven Lord]

Or assemble a vector of values of R, one value per loop iteration, then plot that vector after the loop is complete.

R = zeros(size(x)); % Preallocate
for i = 1:length(x)
  ...
  R(i) = ...
end
plot(L1, R, '*')