--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolbox/cpltaxes.m	Thu May 07 18:36:24 2015 +0200
@@ -0,0 +1,37 @@
+function x = cpltaxes(z)
+%CPLTAXES   Determine suitable AXIS for plot of complex vector.
+%           X = CPLTAXES(Z), where Z is a complex vector,
+%           determines a 4-vector X such that AXIS(X) sets axes for a plot
+%           of Z that has axes of equal length and leaves a reasonable amount
+%           of space around the edge of the plot.
+
+%           Called by FV, GERSH, PS and PSCONT.
+
+% Set x and y axis ranges so both have the same length.
+
+xmin = min(real(z)); xmax = max(real(z));
+ymin = min(imag(z)); ymax = max(imag(z));
+
+% Fix for rare case of `trivial data'.
+if xmin == xmax, xmin = xmin - 1/2; xmax = xmax + 1/2; end
+if ymin == ymax, ymin = ymin - 1/2; ymax = ymax + 1/2; end
+
+if xmax-xmin >= ymax-ymin
+   ymid = (ymin + ymax)/2;
+   ymin =  ymid - (xmax-xmin)/2; ymax = ymid + (xmax-xmin)/2;
+else
+   xmid = (xmin + xmax)/2;
+   xmin = xmid - (ymax-ymin)/2; xmax = xmid + (ymax-ymin)/2;
+end
+axis('square')
+
+% Scale ranges by 1+2*alpha to give extra space around edges of plot.
+
+alpha = 0.1;
+x(1) = xmin - alpha*(xmax-xmin);
+x(2) = xmax + alpha*(xmax-xmin);
+x(3) = ymin - alpha*(ymax-ymin);
+x(4) = ymax + alpha*(ymax-ymin);
+
+if x(1) == x(2), x(2) = x(2) + 0.1; end
+if x(3) == x(4), x(4) = x(3) + 0.1; end