I want to add a 20 by 20 matrix to a 50 by 50 matrix ? the resuting matrix should be of 50 by 50 .

For Example : A=5*ones(50) & B=2*ones(20) , how should A+B be evaluated ?

[Guillaume]

You tell us how it should be evaluated since it makes no sense mathematically.

Possibly you want to pad the smaller matrix with 0, only you knows.

[Amir]

Mr. Raghavendra did right what i wanted ! But ur question was also in my mind to pad zeros with the smaller matrix. How would u do it

[Guillaume]

Exactly, the way Raghavendra did it, or using padarray if you have the imaging toolbox.

Answer 1

[RAGHAVENDRA]

 A=5*ones(50)
B=zeros(50);
B(1:20,1:20)=2*ones(20);
C=A+B;

[Amir]

Thats exactly what i wanted !

Answer 2

[Jos (10584)]

For arbitrary sized 2D matrices A and B:

% example data
  A = ones(3,5) 
  B = 2*ones(4,2) 
% engine
  szA = size(A)
  szB = size(B)
  C = zeros(max([szA ; szB]))
  C(1:szA(1),1:szA(2)) = A
  C(1:szB(1),1:szB(2)) = C(1:szB(1),1:szB(2)) + B