Graphics

Plotting Imaginary and Complex Data

When the arguments to plot are complex (i.e., the imaginary part is nonzero), MATLAB ignores the imaginary part except when plot is given a single complex argument. For this special case, the command is a shortcut for a plot of the real part versus the imaginary part. Therefore,

• plot(Z)
  

where Z is a complex vector or matrix, is equivalent to

• plot(real(Z),imag(Z))
  

For example, this statement plots the distribution of the eigenvalues of a random matrix using circular markers to indicate the data points.

• plot(eig(randn(20,20)),'o','MarkerSize',6)
  
  
  

To plot more than one complex matrix, there is no shortcut; the real and imaginary parts must be taken explicitly.

Line Plots of Matrix Data

Plotting with Two Y-Axes