Using Contour to plot different range data.

For the past 2 hours I am trying to plot my x,y,z data using contour and even after reading examples from MATLAB I am still at the same place. Just for learning purposes I am using dummy data that I have created shown below:

x=1:0.5:20;
y=1:0.5:10;

z=zeros(39,19);

for i=1:1:39
    for j=1:1:19
    z_value=x(j)+y(j)^2-2*x(i);
    z(i,j)=z_value;
    end 
end 

for i=1:1:38
    for j=1:1:19
        plot3 (x(i),y(j),z(i,j),'ro-')
        hold on
    end 
end

While I am good with plotting it all in 3D, I would like to plot contours however, whenever I try to plot contour(x,y,z) it gives me following message:

*******************************

Error using contour (line 81)
The size of X must match the size of Z or the
number of columns of Z.

Error in test (line 23)
contour (x,y,z)

*******************************

The size of X and Y do match Z! So I am not sure what I am missing. If I cannot use contour, can you please suggest another method in order to obtain similar effect graphing tool?

Thank you for your time.

Answer 1

[Walter Roberson]

length(x) matches the number of rows in z, but it needs to match the number of columns in z.

Try

contour(x, y, z.')

[Katarina]

Thank you Walter! I appreciate it. I do tend to mix rows and columns more than I should :/ .. but I do not think that I would come to that solution any time soon. At least I am learning!

[McWoz]

So, I have changed my X vector to match the columns of Z, but I am still getting this error... is there a bug?

[Walter Roberson]

McWoz, what is size(x), size(y), size(z) for you?