I need to plot eigen values with Imaginary axis in log scales?

Need help to plot eigen values with Imaginary axis in log scales?

[Siddhant Maurya]

otherwise plotting eigen values with real axis in log scales will also do?

[Jonas]

so whats the problem here?

someComplex=rand(5,1)+1i*rand(5,1)

someComplex = 
   0.6257 + 0.8031i
   0.8168 + 0.6693i
   0.8646 + 0.1120i
   0.9827 + 0.4830i
   0.4358 + 0.2156i

plot(someComplex,'x');
set(gca,'YScale','log');

xlabel('real part');
ylabel('imaginary part (i)')

Answer 1

[Gobiha Duraisamy]

Currently, there is no direct function to plot one of the axis in log scale. As a workaround, you can set the appropriate scale to "log" as follows,

lamda = -rand(3,1)+1i*rand(3,1)       % create three random set of eigenvalues

lamda = 
  -0.6889 + 0.2015i
  -0.9937 + 0.1999i
  -0.7680 + 0.2688i

plot(lamda,'o','LineWidth',3)
set(gca,'YScale','log')
grid on;

If you want to set the real part in log scale, use the following line of codes instead,

plot(lamda,'o','LineWidth',3)
set(gca,'XScale','log')
grid on;

Both X and Y coordinates are plotted in log scale using "loglog" function as follows,

loglog(lamda,'o','LineWidth',3)
grid on;

[Jonas]

"Currently, there is no direct function to plot one of the axis in log scale." thats not true, look into semilogx() and semilogy()

[Siddhant Maurya]

It doesn't work. Try taking complex number in all 4 quadrants and then plot them.