ezcontourf (MATLAB Functions)

Easy to use filled contour plotter

Syntax

ezcontourf(fun)
ezcontourf(fun,domain)
ezcontourf(...,n)
ezcontourf(axes_handle,...)
h = ezcontourf(...)

Description

ezcontourf(fun) plots the contour lines of fun(x,y)using the contourf function. fun is plotted over the default domain: -2 < x < 2, -2 < y < 2.

fun can be a function handle for an M-file function or an anonymous function (see Function Handles and Anonymous Functions) or a string (see the Remarks section).

ezcontourf(fun,domain) plots fun(x,y) over the specified domain. domain can be either a 4-by-1 vector [xmin, xmax, ymin, ymax] or a 2-by-1 vector [min, max] (where min < x < max, min < y < max).

ezcontourf(...,n) plots fun over the default domain using an n-by-n grid. The default value for n is 60.

ezcontourf(axes_handle,...) plots into the axes with handle axes_handle instead of the current axes (gca).

h = ezcontourf(...) returns the handles to contour objects in h.

ezcontourf automatically adds a title and axis labels.

Remarks

Passing the Function as a String

Array multiplication, division, and exponentiation are always implied in the string expression you pass to ezcontourf. For example, the MATLAB syntax for a filled contour plot of the expression

```
sqrt(x.^2 + y.^2);
```

is written as

```
ezcontourf('sqrt(x^2 + y^2)')
```

That is, x^2 is interpreted as x.^2 in the string you pass to ezcontourf.

If the function to be plotted is a function of the variables u and v (rather than x and y), then the domain endpoints umin, umax, vmin, and vmax are sorted alphabetically. Thus, ezcontourf('u^2 - v^3',[0,1],[3,6]) plots the contour lines for u² - v³ over 0 < u < 1, 3 < v < 6.

Passing a Function Handle

Function handle arguments must point to functions that use MATLAB syntax. For example, the following statements define an anonymous function and pass the function handle fh to ezcontourf.

fh = @(x,y) sqrt(x.^2 + y.^2);
ezcontourf(fh)

Note that when using function handles, you must use the array power, array multiplication, and array division operators (.^, .*, ./) since ezcontourf does not alter the syntax, as in the case with string inputs.

Passing Additional Arguments

If your function has additional parameters, for example k in myfun:

function z = myfun(x,y,k)
z = x.^k - y.^k - 1;

then you can use an anonymous function to specify that parameter:

```
ezcontourf(@(x,y)myfun(x,y,2))
```

Examples

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

ezcontourf requires a string argument that expresses this function using MATLAB syntax to represent exponents, natural logs, etc. This function is represented by the string

f = ['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)'];

For convenience, this string is written on three lines and concatenated into one string using square brackets.

Pass the string variable f to ezcontourf along with a domain ranging from -3 to 3 and specify a grid of 49-by-49:

```
ezcontourf(f,[-3,3],49)
```

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

See Also

contourf, ezcontour, ezmesh, ezmeshc, ezplot, ezplot3, ezpolar, ezsurf, ezsurfc, function_handle

Contour Plots for related functions

ezcontour ezmesh