Matlab Surface: Assign different color for specific portions of the graph.

Hi guys,

Is it possible to color different areas of ONE surface? and also have a legend?

Can I ask that anything > (25,25) be blue and less be red in the following example? Thanks!

x = [0:50];
y = [0:50];

Test1 = @(x,y) x.^2+y.^2;

[X1,Y1] = meshgrid(x,y);
Z1 = Test1(X1,Y1);
s1 = surf(X1,Y1,Z1,'LineStyle','none');

Answer 1

[Ahmet Cecen]

How about:

x = [0:50];
y = [0:50];
Test1 = @(x,y) x.^2+y.^2;
[X1,Y1] = meshgrid(x,y);
Z1 = Test1(X1,Y1);
s1 = surf(X1,Y1,Z1,'LineStyle','none');
s1.FaceColor='blue';

hold on;

x = [0:25];
y = [0:25];
Test1 = @(x,y) x.^2+y.^2;
[X1,Y1] = meshgrid(x,y);
Z1 = Test1(X1,Y1);
s1 = surf(X1,Y1,Z1,'LineStyle','none');
s1.FaceColor='red';

[A]

Looks pretty good. Any way to add a legend to this?

Thanks

[Ahmet Cecen]

 legend('blue','red')

[A]

Hi Ahmet,

Thanks very much. This is almost there. When I put this into my more complex formula, it gets a little confusing. Basically, when you graph this, is there a way to tell Matlab not to graph the green bit where Z = 0?

x = [0:10];
y = [0:10];

Eq1 = @(x,y)(x+y);
Eq2 = @(x,y)(2.*x+y);

BigEq = @(x,y) [Eq1(x,y).*(Eq2(x,y)>5)];
[X1,Y1] = meshgrid(x,y);
Z1 = BigEq(X1,Y1);
s1 = surf(X1,Y1,Z1);
set(s1,'FaceColor','green');
hold on;

x = [5:10];
y = [5:10];
BigEq = @(x,y) [Eq1(x,y).*(Eq2(x,y)>5)];
[X1,Y1] = meshgrid(x,y);
Z1 = BigEq(X1,Y1);
s1 = surf(X1,Y1,Z1);
set(s1,'FaceColor','red');
hold off;

[Ahmet Cecen]

x = [0:10];
y = [0:10];
Eq1 = @(x,y)(x+y);
Eq2 = @(x,y)(2.*x+y);
BigEq = @(x,y) [Eq1(x,y).*(Eq2(x,y)>5)];
[X1,Y1] = meshgrid(x,y);
Z1 = BigEq(X1,Y1);
Z1(Z1==0)=NaN; % Get rid of zeros.
Z1(7:10,7:10)=NaN; % Get rid of the green surface where red will come, to resolve clipping.
s1 = surf(X1,Y1,Z1);
set(s1,'FaceColor','green');
hold on;
x = [5:10];
y = [5:10];
BigEq = @(x,y) [Eq1(x,y).*(Eq2(x,y)>5)];
[X1,Y1] = meshgrid(x,y);
Z1 = BigEq(X1,Y1);
s1 = surf(X1,Y1,Z1);
set(s1,'FaceColor','red');
hold off;