contourf

Arguments

x, y

two real row vectors of size n1 and n2: the grid.

z

a real matrix of size (n1,n2), the values of the function.

nz

the level values or the number of levels.

-

If nz is an integer, its value gives the number of level curves equally spaced from zmin to zmax as follows:

z= zmin + (1:nz)*(zmax-zmin)/(nz+1)

Note: that the zmin and zmax levels are not drawn (generically they are reduced to points) but they can be added with

[im,jm] = find(z == zmin);     // or zmax
plot2d(x(im)',y(jm)',-9,"000")

-

If nz is a vector, nz(i) gives the value of the i-th level curve.

style, strf, leg, rect, nax

see plot2d. The argument style gives the colors which are to be used for level curves. It must have the same size as the number of levels.

fpf

You can change the format of the floating point number printed on the levels where fpf is the format in C format syntax (for example fpf="%.3f"). Set fpf to " " implies that the level are not drawn on the level curves. If not given, the default format of contour2d is used.

Description

contourf paints surface between two consecutive level curves of a surface z=f(x,y) on a 2D plot. The values of f(x,y) are given by the matrix z at the grid points defined by x and y.

Enter the command contourf() to see a demo.

Examples

contourf(1:10,1:10,rand(10,10),5,1:5,"011"," ",[0,0,11,11])

function z=peaks(x, y)
x1=x(:).*.ones(1,size(y,'*'));
y1=y(:)'.*.ones(size(x,'*'),1);
z =  (3*(1-x1).^2).*exp(-(x1.^2) - (y1+1).^2) ...
   - 10*(x1/5 - x1.^3 - y1.^5).*exp(-x1.^2-y1.^2) ...
   - 1/3*exp(-(x1+1).^2 - y1.^2)
endfunction

function z=peakit()
x=-4:0.1:4;y=x;z=peaks(x,y);
endfunction

z=peakit();

levels=[-6:-1,-logspace(-5,0,10),logspace(-5,0,10),1:8];
m=size(levels,'*');
n = fix(3/8*m);
r = [(1:n)'/n; ones(m-n,1)];
g = [zeros(n,1); (1:n)'/n; ones(m-2*n,1)];
b = [zeros(2*n,1); (1:m-2*n)'/(m-2*n)];
h = [r g b];
gcf().color_map = h;
clf();
contourf([],[],z,[-6:-1,-logspace(-5,0,10),logspace(-5,0,10),1:8]);

See also

• contour — level curves on a 3D surface
• contour2d — level curves of a surface on a 2D plot
• contour2di — compute level curves of a surface on a 2D plot
• plot2d — 2D plot