CODEWITHSUNDEEP
matlabplotmesh
Szymon Kocot
Szymon Kocot

Reputation: 138

Matlab mesh plot. Specific function for z. Z must be a matrix

I'd like to make a function, that will be making a mesh plot. start x,y; dx,dy and end x,y will be inputted into a function. Z should be calculated like there:

if x>y
     z =x^2-sin(x);
elseif x==y
     z = 3;
else
     z = 2*x+2*x;
end

I've made this code:

function []= mes(xp,xk,dx,yp,yk,dy)
x=[xp:dx:xk];
y=[yp:dy:yk];
zv=[];

for i=1:numel(x)
        if x>y
            z=x(i)^2-sin(y(i));
        elseif x(i)==y(i)
            z=3;
        else
            z=2*x(i)+2*y(i);    
        end
    zv=[zv z];
end
[X,Y]=meshgrid(x,y);
figure
x
y
zv
mesh(X,Y,zv)

and got these error codes:

Error using mesh (line 70)
Z must be a matrix, not a scalar or vector.

Error in mes (line 21)
mesh(X,Y,zv)

Equation for z seems to work. I know, that there are many answers to simillar problems as mine, but when I make a simple equation for z it works, but not with this one.

Upvotes: 0

Views: 147

Answers (1)

Ander Biguri
Ander Biguri

Reputation: 35525

Use Vectorization!

x=[xp:dx:xk];
y=[yp:dy:yk];
[X,Y]=meshgrid(x,y);

z=zeros(size(X));

z=2*X+2*Y; 
z(X>Y)=X((X>Y)).^2-sin(Y((X>Y)));
z(X==Y)=3; % Careful with floating points!! maybe abs(X-Y)<0.00001 ?

mesh(X,Y,Z);

Upvotes: 1

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