Error code : In an assignment A(I) = B, the number of elements in B and I must be the same.

When I type the following commands:

    [X,Y] = meshgrid(0:.2:1, 0:.2:1);
    surf(X,Y,mFunction(X,Y))

matlab gives me the following error :

In an assignment  A(I) = B, the number of elements in B and I must be the same.
Error in mFunction (line 40)
    L(i)=alpha.*MS3(i)+(1-alpha).*L(i-1);

How should I proceed? Thanks!

[Image Analyst]

How are X and Y being used in mFunction? You're not showing that. Also, what is the value of i and alpha when it errors? By the way, do you know how to use the debugger?

Answer 1

[Walter Roberson]

Your function is not vectorized. You will need to use

      Z = arrayfun(@mFunction, X, Y);
      surf(X, Y, Z, 'edgecolor', 'none')

but it would be much more efficient to vectorize your function.

At the very least you should pull the xlsread() out of the function, assign the appropriate extracted values to a variable in the calling code, and have the calling code pass the value in to the function. xlsread() can be pretty slow.

[amine&&]

Thanks Roberson that's what i was searching for. But how can i vectorize this function?

[Walter Roberson]

I have no idea what it calculates or how, since the comments took a vacation and never came back. But I would point out, for example, that

L=zeros(288,1);
L(25)=MS3(25);
for i=26:264;
    L(i)=alpha.*MS3(i)+(1-alpha).*L(i-1);
end

could be replaced by

numalpha = length(alpha);

L = zeros(288, numalpha);
L(25,:) = MS3(25);
for i = 26:264;
    L(i,:) = alpha.*MS3(i) + (1-alpha).*L(i-1,:);
end

That would not be the only required change.

[amine&&]

Thanks Roberson!