I expect Z to return at least a 2x2 matrix. Z is supposed to be the height of the sphere and X1 the x-axis and X2 the y-axis.
Here is the whole code:

M = 100; % population sizen = 2;pop = 0 + 1.*randn(M,n);[popSize d] = size(pop);G = 25; % number of generations for the fitness evaluation functionMax_F = 1000; % maximal number of FEsoptions.optmType = 'max';y = zeros(1,G);for i =1:G eval = sphere(pop); % fitness evaluation of the initial population.% Setting Criteria for selecting N(<=M)if ~isfield(options, 'optmType') error('Please provide optimisation type {min, max}');end% define best population sizeif isfield(options, 'topSize') topSize = options.topSize; if topSize > popSize disp('Warning: topSize is larger than popSize, will use, popSize/10'); topSize = 0.25 * popSize; options.topSize = topSize; endelse topSize = 0.25 * popSize; options.topSize = topSize;end% all initial pop are top_xtop_x = pop;% Criteria for selecting top 'topSize' individuals based on fitness% values(eval) if strcmp(options.optmType, 'min') [void, b] = sort(eval, 'descend'); % maximising else [void, b] = sort(eval, 'ascend'); % minimising end top_x = pop(b(1:options.topSize),:); % select top individuals optm_x = pop(b(1),:); % save optimal parameter fv = eval(b(1)); % save optimal func. value mu = mean(top_x); % mean vector calculation Sigma = cov(top_x); % Covariance calculation pop = mvnrnd(mu,Sigma,M); % Calculate joint probability distribution of selected individuals(sampling) dstring = [num2str(M), ' samples are generated.'];subplot(1,2,1);y(i) = sphere(optm_x); plot(y(1:i));xlabel('Generations')ylabel(' Best Individuals')title(sprintf('At the some Generations'))%axis('equal');cmin = -25;cmax = 25;ngrid = 25;cvals = linspace(cmin, cmax, ngrid); % Create the mesh[X1, X2] = meshgrid(cvals, cvals); % Create the gridZ = sphere(X1);subplot(1,2,2);contour(X1, X2, Z);end

Your sphere function is wrong. It needs to take two arguments (x and y coordinates). You have X1 and X2 (which look good). You did try to pass them to sphere before, but it was only set to take one argument. It certainly needs both (actually maybe a third for the radius).
The function for a sphere is x^2+y^2+z^2 = r^2 (where r is the radius).

So you need to solve that equation for Z and that's your sphere function.

function ph = sphere(x, y, r)
ph = 'sphere equation

The plot is showing the data you gave it. Your sphere function is not giving the correct points.
Post your sphere function again. You modified it to use X1 and X2 right? You need to change it to take both.

So the way the contour function works is you pass it a grid and the Z axis values for the X and Y coordinates.
So you pass X1 and X2 as the x and y coords for the grid. This looks fine.
Then you pass Z for the actual Z axis values (the "height" of the contour) at each point in the grid.

Your function that gives these values just squares the X axis values. That's not a sphere.

Your sphere function needs to actually generate a sphere if you want to see a sphere shaped curve. You'll need to re-evaluate what you really want from sphere(pop). Maybe you need two functions? You need to use the actual equation of a sphere to get a sphere z = sqrt(r^2 - x^2 - y^2)

Okay. So you aren't actually trying to plot a sphere. That's fine.
You are still going to run into the problem that your Z is a vector, not a matrix.
If you just output Z, what do you get for the values?

Is there anyone here who knows Estimation of Distribution Algorithm (EDA). This is the algorithm i am trying to implement to understand it. I am trying to plot the sphere function to test it. The test functions can be found Here.
I want to plot the sphere function as a surface or a contour plot, and the position and fitness value of the best individual superimposed with it. The plot will change in each generation so i get a movie. Also, on another figure, i want to plot the contour of the sphere function superimposed with the entire population, with the retained fit individuals colored in red. This from generation to generation should give another movie.

What is it that you want your sphere function to be doing?
Currently, it is taking a vector, squaring each element of the vector and returning it summed by row.

So sphere([1, 2, 3, 4]) returns [1, 4, 9, 16];

if you passed it
[[1] [2] [3] [4]]
it would return [[31]] (sum of all elements).

Is that what you want? In order to make a contour, your Z needs to be a matrix, not a vector.

If sphere was x*transpose(x) instead of sum(x.*x,2) then you could pass it a vector and it would return a matrix.

Glad to hear it's plotting now.
Yes. I am currently finishing my PhD at S&T. Do I know you? You can email me if you want to take the social aspect of this conversation offline. I'm sure you can find my email address if you are at the university.

The above code should superimpose contour plot and BestId. For each loop of l, a bestId is generated and superimposed with the contour plot. This generation of BestInd should take place for each l. but among the generations of bestId from 1 to 4, there is one which is the best of them and we should get that after four generation which is superimposed with the contour plot. Now i want this generation to be a movie for reach iteration from 1 to 4, so that i can see how the bestId are generated untill the best(optimal) one is achieved. this is what i meant by movie in matlab. Any idea on how this could be done?

Can someone help me with the above problem please? Here is what i am trying to achieve. Sample.ppt. If you download the ppt and have a slideshow, you will see how i want the plot to be at each generation, thus creating a Movie to see how the points moves slowly to the global optimum.

The whole code i wrote to achieve this is in my post @ ID: 39196865

If the original problem is solved (plotting the contour), then your best bet would be to close this question (since it was answered) and open a new one for the new problem (the movie). That way other people will look at it besides just me and it will have a better chance at a good fast answer.

I will be happy to look at this again, but I don't have MATLAB on this computer and it may be a bit before I have the time. If you use the same zones, I will get an email when you ask the next step.

Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilationâ€¦

The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.