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

hi I have got a problem with the following code. When it's excuted, i receive the error "In an assignment A(I) = B, the number of elements in B and I must be the same." sadly i couldn't find so far the problem in the code. Can somebody find the mistake?

if true
  function [re]=elementlasttensor(p,El,NG)

q=[0 0;10 7.5;7.5 5;0 0;0 0]; E=[210 210 210 70 210]*10^9; A=[0.05 0.05 0.05 0.05 0.05]; L=[1 1 1 2 1]; Knotenlast=[0 0 0 1 0]; Element=[1 2 3 4 5];

re=zeros(p+1);

if NG==1 alpha=2; psi=0;

               elseif NG==2
                   alpha=[1 1];
                   psi=[-1/sqrt(3) 1/sqrt(3)];

               elseif NG==3
                   alpha=[(5/9) (8/9) (5/9)];
                   psi=[-sqrt(3/5) 0 sqrt(3/5)];

               elseif NG==4
                   alpha=[0.34785 0.65241 0.65241 0.34785];
                   psi=[-0.86114 -0.33998 0.33998 0.86114];

               else

end

%for Element=1:El

for g=1:NG [N]=Ansatzfunktion(p,psi(g));

   b=0;

   for j=1:p+1
       b=b+N(j)*q(Element,j);
   end
   for i=1:p+1
       re(i)=re(i)+N(i)*b*(L/2)*alpha(g);

   end   
end 
end
%end
  end

the variables are EL=5, NG=4 and p=1

Answer 1

[Paul]

Probably this line:

   b=b+N(j)*q(Element,j);

Element is a vector itself. It should be a scalar but i dont know exactly what you want to do so you got to figure it out yourself what it should be. There may more problems with your script, though. Also, matlab outputs the exact line where the error happens, so you should be able to debug yourself by reviewing that specific line.

Answer 2

[Amit]

The problem is in

re(i)=re(i)+N(i)*b*(L/2)*alpha(g);

b is (n*1) matrix and L is a (1,n) matrix. If you are doing, what I think you are doing (matrix multiplication), the correct code should be:

re(i)=re(i)+N(i)*((L/2)*b)*alpha(g);

Your version of re(i) creates a n*n matrix and that why the error comes.