contour with latest CVS and gnuplot 4.0

[John W. Eaton]

On 23-Mar-2007, David Bateman wrote:

| I get no output with
| 
| [x,y] = meshgrid(-10:10); z =1./sqrt(x.^2 + y.^2); contour(z)
| 
| or with
| 
| [x,y] = meshgrid(-10:10); z =1./sqrt(x.^2 + y.^2); contour(x,y,z)
| 
| with a recent CVS and gnuplot 4.0. Is this expected? If it is expected
| is there a way around it?

The contour function was changed recently to use the contour functions
from octplot to generate the contour lines which are then plotted
using 2-d plotting commands (the line function).  The first thing that
happens in a call like

  contour (z)

is

  [c, lev] = contourc (z);

For your Z, I see

  c = [](2x0)
  lev =

     Inf   Inf   Inf   Inf   Inf   Inf   Inf   Inf   Inf   Inf

and there is nothing to plot.  I haven't looked to see why this might
be happening.

jwe