How to fix "The size of the indicated variable or array appears to be changing with each loop iteration?"

Hello Guys,I am student and doing some project on Torsional constant for any cross section . I am using mat lab and i could not fix one error message.Is there any one can help me? (I got this code on internet which one gentle man did his research on this field ) Here is the code fragment

 A = sparse( size(coordinates,1), size(coordinates,1) );
  for j = 1 : size(elements3,1)
   A(elements3(j,:),elements3(j,:)) = A(elements3(j,:),elements3(j,:)) + ...stima3(coordinates(elements3(j,:),:));
    end

Here is the error message "The size of the indicated variable or array appears to be changing with each loop iteration. Commonly, this message appears because an array is growing by assignment or concatenation. Growing an array by assignment or concatenation can be expensive. For large arrays, MATLAB must allocate a new block of memory and copy the older array contents to the new array as it makes each assignment"

[Henric Rydén]

A seems to be growing because there is not enough space allocated in the first line. Can you tell us what elements3 contains, and the size of coordinates?

[Abe Ada]

 oh,element 3 contains coordinate elements of triangles for which user enters from key bored or load it from  file. 
eg 
  load elements3.dat;or
 element3 contains( Node1,node2,node3)
node1(x1,y1),node2(x2,y2) ,node3(x3,y3)-----

[Henric Rydén]

What is the size of coordinates?

What is the size of elements3? Do you know that size before the loop begins?

Answer 1

[merina amon]

facing the same problem, need help with this.

for k=1:101

t=tk(k);

for i=3:4

x(k,i-2)=0;

for j=1:4

x(k,i-2)=x(k,i-2)+(real(S(j))*real(V(i,j))-imag(S(j))*imag(V(i,j)))*cos(imag(D(j,j))*t);

x(k,i-2)=x(k,i-2)+(imag(S(j))*real(V(i,j))-real(S(j))*imag(V(i,j)))*sin(imag(V(i,j))*t);

x(k,i-2)=x(k,i-2)*exp(-real(D(j,j))*t);

end