
 Usage

This command generates contour plots. There are several
syntaxes for the command. The simplest is

    contour(Z)

which generates a contour plot of the data in matrix Z, and
will automatically select the contour levels. The x,y
coordinates of the contour default to 1:n and 1:m, where n
is the number of columns and m is the number of rows in the
Z matrix. Alternately, you can specify a scalar n

    contour(Z,n)

which indicates that you want n contour levels. For more
control, you can provide a vector v containing the levels to
contour. If you want to generate a contour for a particular
level, you must pass a vector [t,t] where t is the level you
want to contour. If you have data that lies on a particular
X,Y grid, you can pass either vectors x,y or matrices X,Y to
the contour function via

    contour(X,Y,Z)
    contour(X,Y,Z,n)
    contour(X,Y,Z,v)

Each form of contour can optionally take a line spec to
indicate the color and linestyle of the contours to draw:

    contour(...,linespec)

or any of the other forms of contour. Furthermore, you can
supply an axis to target the contour plot to (so that it
does not get added to the current axis, which is the
default):

    contour(axis_handle,...)

Finally, the contour command returns a handle to the newly
returned contour plot.

    handle = contour(...)

To place labels on the contour plot, use the clabel
function.


 Example

Here is a simple example of a contour plot with the default
x,y coordinates:

  --> [x,y] = meshgrid(linspace(-1,1,25),linspace(-2,2,30));
  --> z = x.*exp(-x.^2-y.^2);
  --> contour(z)

which results in the following plot
 contour1.png
Here, we specify the x and y coordinates explictly

  --> contour(x,y,z)

note that the axis limits have changed appropriately
 contour2.png
By default, contours are created at values selected by
FreeMat. To provide our own set of contour values
(asymmetrically about zero in this case), we supply them as

  --> contour(x,y,z,[-.4,0.,3])

which is here
 contour3.png
Also be default, contour uses the current color map and clim
limits to determine the coloring of the contours. Here, we
override the color spec so that we have all black contour

  --> contour(x,y,z,'b-')

which is here
 contour4.png

* FreeMat_Documentation
* Handle-Based_Graphics
* Generated on Thu Jul 25 2013 17:17:20 for FreeMat by
  doxygen_ 1.8.1.1

