Assigned solve outputs to a matrix via for loops

Hello, I am having a problem where I am attempting to solve an equation inside of a for loop and assign its result to the respective matrix cell. It has inputs from a matrix of the same size as it should be outputting to, yet I still get the error "Assignment has more non-singleton rhs dimensions than non-singleton subscripts". Here is my relevant code:

for i=1:s  % i is steps of t
    for j = 1:s  % j is steps of r
        Ac(i,j) = 2*pi*rp(j)*t(i);
        if Ac(i,1)<An
            Acrit(i,j) = Ac(i,1);     % For distances less than .025mm
        else
            Acrit(i,j) = An;     % For everything else
        end
        Aratio(i,j) = Ac(i,j)/Acrit(i,j);

      end
  end

for i=1:s
    for j=1:s
        M = sym('M');
        macheqn(i,j) = 1/M*(2/(k+1)*(1+(k-1)/2*M^2))^((k+1)/(2*(k-1)));
        assume(M,'real');
        Mach(i,j)=double(solve(macheqn(i,j)==Aratio(i,j),M));
    end
end

[Darshan Ramakant Bhat]

What is 'An' is it a matrix or a constant? It would be better if you give input data as well

[Walter Roberson]

Should we assume that k is a scalar?

Is there a reason to assign the same value to all elements of macheqn?

Your macheqn is not going to have an analytic solution so use vpasolve instead of solve.

Careful: the macheqn can have two solutions.

Answer 1

[Nanda Gupta]

I understand that you want to solve an equation iteratively inside the for loop and assign its answer each time in to a respective matrix cell.

This error is a result of incorrect indexing of multidimensional arrays. Check out this documentation for indexing the multidimensional arrays: http://www.mathworks.com/help/matlab/math/multidimensional-arrays.html;jsessionid=b58f142b9ecaa292bc0adfa73247#f1-86846

Answer 2

[Walter Roberson]

It looks likely to me that your solve() is returning an empty expression. double() of that is empty, and you would then be trying to store empty into a location of size 1.

We would need the values of the other variables to test this ourselves.

Try using vpasolve() instead of solve()