How do I plot complex numbers or moduli?

Dear Readers,

I have this code. However, there might be a mixture of imaginary and real eigenvalues. I want to plot everything or, if alle eigenvalues are complex, only the moduli. How do I go about this?

eigVals = zeros(2,numel(p));

figure
for k = 1:numel(p)
      A = J(c(k), p(k), R(k), c2(k), p2(k));
      eigVals(:,k) = eig(A);
      hold on;
      plot(p(k), eigVals(:,k)', '*');
end

Answer 1

[KSSV]

You can check whether a value is real or complex using isreal. To get moduli or magnitude of complex number you can use abs. Read about isreal, abs. https://in.mathworks.com/help/matlab/complex-numbers.html

[Sean]

Great. I adapted the code, however plotting gives the error 'Data must be a single matrix Y or a list of pairs X,Y.'

eigVals = zeros(2,numel(p));
real_ev = [ ];
imag_ev = [ ];

figure
for k = 1:numel(p)
      A = J(c(k), p(k), R(k), c2(k), p2(k));
      eigVals(:,k) = eig(A);
      real_ev(:,k) = real(eigVals(:,k));
      imag_ev(:,k) = imag(eigVals(:,k));
      hold on;
      plot(p(k), real_ev(:,k)', 'g*', imag_ev(:,k)', 'b*');
end

Thanks in advance

[KSSV]

Size of p(k) and real_ev(:,k) should be same to plot. Also the plot line should be plot(p(k), real_ev(:,k)', 'g*', p(k),imag_ev(:,k)', 'b*');