ezcontour

(Not recommended) Easy-to-use contour plotter

ezcontour is not recommended. Use fcontour instead. For more information, see Version History.

Syntax

ezcontour(f)

ezcontour(f,xyinterval)

ezcontour(___,n)

ezcontour(ax,___)

c = ezcontour(___)

Description

ezcontour(f) plots the contour lines of the function z = f(x,y) using the contour function. The function plots f over the default interval [-2π 2π] for x and y.

ezcontour automatically adds a title and axis labels to the plot.

ezcontour(f,xyinterval) plots over the specified interval. To use the same interval for both x and y, specify xyinterval as a two-element vector of the form [min max]. To use different intervals, specify a four-element vector of the form [xmin xmax ymin ymax].

ezcontour(___,n) plots using an n-by-n grid. Use this option after any of the input argument combinations in the previous syntaxes.

ezcontour(ax,___) plots into the axes specified by ax instead of the current axes. Specify the axes before any of the input argument combinations in any of the previous syntaxes.

c = ezcontour(___) returns the contour object. Use c to modify the contour after it is created. For a list of properties, see Contour Properties.

Examples

Create Contour Plot of Mathematical Expression

This mathematical expression defines a function of two variables, x and y.

$$f(x,y)=3(1-x{)}^2{e}^{-x^2-(y+1{)}^2}-10(\frac{x}{5}-x^3-y^5)e^{-x^2-y^2}-\frac{1}{3}{e}^{-(x+1{)}^2-y^2}$$

The ezcontour function requires a function handle argument. Write this mathematical expression in MATLAB® syntax as an anonymous function with handle f. You can define an anonymous function in the command window without creating a separate file. For convenience, write the function on three lines.

f = @(x,y) 3*(1-x).^2.*exp(-(x.^2) - (y+1).^2) ...
   - 10*(x/5 - x.^3 - y.^5).*exp(-x.^2-y.^2) ...
   - 1/3*exp(-(x+1).^2 - y.^2);

Pass the function handle, f, to ezcontour. Specify a domain from -3 to 3 in both the x-direction and y-direction and use a 49-by-49 computational grid.

ezcontour(f,[-3,3],49)

In this particular case, the title is too long to fit at the top of the graph, so MATLAB abbreviates it.

Input Arguments

f — Function to plot

character vector | string scalar | function handle

Function to plot, specified as a character vector, string scalar, or function handle to a named or anonymous function.

Specify a function of the form z = f(x,y). The function must accept two matrix input arguments and return a matrix output argument of the same size.

When specifying the function as a character vector or string scalar, array multiplication, division, and exponentiation are always implied. For example, x^2 is interpreted as x.^2.

Example: 'sqrt(x^2 + y^2)'

When specifying the function as a function handle, use array operators instead of matrix operators for the best performance. For example, use .* (times) instead of * (mtimes).

Example: @(x,y) sin(x).*cos(y)

xyinterval — Plotting interval for x and y

[–2π 2π -2π 2π] (default) | vector of form [min max] | vector of form [xmin xmax ymin ymax]

Plotting interval for x and y, specified in one of these forms:

• Vector of form [min max] — Use the interval [min max] for both x and y.

• Vector of form [xmin xmax ymin ymax] — Use the interval [xmin xmax] for x and [ymin ymax] for y.

n — Size of the grid

60 (default) | positive integer

Size of the grid, specified as a positive integer. The grid has dimensions n-by-n.

ax — Axes object

axes object

Axes object. If you do not specify an axes object, then the ezcontour uses the current axes.

Extended Capabilities

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The ezcontour function supports GPU array input with these usage notes and limitations:

• This function accepts GPU arrays, but does not run on a GPU.

For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

Usage notes and limitations:

• This function operates on distributed arrays, but executes in the client MATLAB^®.

For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a

R2016a: ezcontour is not recommended

ezcontour is not recommended. Use fcontour instead. There are no plans to remove ezcontour.

fcontour requires that the input function to plot is a function handle. ezcontour accepts either a function handle, a character vector, or a string. This table shows some typical usages of ezcontour and how to update your code to use fcontour instead.

Not Recommended	Recommended
ezcontour(@(x,y) sqrt(x.^2+y.^2))	fcontour(@(x,y) sqrt(x.^2+y.^2))
ezcontour('sin(x)+cos(y)')	fcontour(@(x,y) sin(x)+cos(y))