misc.plotEigenvalues revised

+misc/plotEigenvalues.m

-function [] = plotEigenvalues(A)
-%PLOT EIGENVALUES plot eigenvalues in complex plane
-%	plotEigenvalues(A) plots the eigenvalues of matrix A in the complex
-%	plane.
+function f1 = plotEigenvalues(A, NameValue)
+%MISC.PLOTEIGENVALUES plot eigenvalues in complex plane
+% f1 = misc.plotEigenvalues(A) returns a figure f1 displaying the eigenvalues of A or, if A is a vector,
+%	then A itself.
+%
+% misc.plotEigenvalues(A, "title", title) sets the title to the string title
+%
+% misc.plotEigenvalues(A1, A2, ..., ) plots all A1, A2, ... in separate subplots
+%
+% misc.plotEigenvalues(A1, A2, ..., "subplot", false) plots all A1, A2, ... the same plot
+%
+% misc.plotEigenvalues(A1, A2, ..., "title", title) sets the title of each subplot to the
+% corresponding value of the string-array title
 
-e = eig(A);
+arguments (Repeating)
+	A (:, :) double;
+end
+arguments
+	NameValue.subplot = true;
+	NameValue.title string = "";
+end
 
-plot(real(e), imag(e), 'r*');
-xlabel('real')
-ylabel('imag')
+if nargin > 0
+	e = cell(size(A));
+	realMin = 0;
+	realMax = 0;
+	imagMin = 0;
+	imagMax = 0;
+	for it = 1 : numel(A)
+		if isvector(A{it})
+			e{it} = A{it};
+		else
+			e{it} = eig(A{it});
+		end
+		
+		realMin = min([real(e{it}); realMin], [], "all");
+		realMax = max([real(e{it}); realMax], [], "all");
+		imagMin = min([imag(e{it}); imagMin], [], "all");
+		imagMax = max([imag(e{it}); imagMax], [], "all");
+	end
+	f1 = figure();
+	for it = 1 : numel(A)
+		if NameValue.subplot
+			subplot(1, numel(A), it);
+		end
+		e = eig(A{it});
+		plot(real(e), imag(e), "Marker", "*", "Color", misc.color(it), "LineStyle", "none");
+		hold on;
+		
+		xlim([realMin, realMax] + diff([realMin, realMax]) * [-1, 1]/10)
+		ylim([imagMin, imagMax] + diff([imagMin, imagMax]) * [-1, 1]/10)
+		xlabel('real')
+		ylabel('imag')
+		if strlength(NameValue.title) > 0
+			if numel(NameValue.title) > 1
+				title(NameValue.title(it));
+			else
+				title(NameValue.title);
+			end
+		end
+	end
+end % nargin > 0
 
-end
+end % function f1 = plotEigenvalues()