matlab - Attempted to access b(1,2); index out of bounds because size(b)=[3,1] -

i have uni assignment create basic function works same backslash command in matlab. i'm not looking answer uni, intentions not cheat, i'm stuck on problem , need guidance on how work.

so think i'm close answer.

function x = matrix_solve(a,b) inva=inv(a);  [m,n] = size(a); % m num rows, n num of columns nb = size(b,1);  if m == n && nb == m     x = zeros(m,n);      = 1:m         j = 1:n             x(1,j) = x(1,j)+ inva(i,1)*b(1,j);         end     end else    error('error') end 

using basic square matrix

b = [1;3;2] = [3,1,2;3,2,1;3,3,3] 

i keep getting error mentioned in title.

i'm pretty familiar other code i'm very new matlab.

the cause of index out of bound error you're trying access element doesn't exist @ line

    x(1,j) = x(1,j)+ inva(i,1)*b(1,j); 

instead should

    x(1,j) = x(1,j)+ inva(i,1)*b(j,1); 

i.e. change b(1,j) b(j,1). bis column vector of size 3 (size(b)=[3,1]) , trying access element @ row 1, column 2, there 1 column.