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ezcontourf

(Not recommended) Easy-to-use filled contour plotter

ezcontourf is not recommended. Use fcontour instead.

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: -2π < x < 2π, -2π < y < 2π.

fun can be a function handle or a character vector (see Tips).

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 the handle axes_handle instead of into the current axes (gca).

h = ezcontourf(...) returns the handle to a contour object in h.

ezcontourf automatically adds a title and axis labels.

Examples

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

 

The ezcontourf 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 ezcontourf. Specify a domain from -3 to 3 in both the x-direction and y-direction and use a 49-by-49 computational grid.

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 it.

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Passing the Function as a Character Vector

Array multiplication, division, and exponentiation are always implied in the character vector 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 character vector 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)

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 character vector inputs.

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))