Asked by Ayob
on 21 Apr 2013

I'm assembling a bigger matrix with elements of other smaller matrixes. in my method I build a connecting vector for example C=[1 5 6 7 8 9] when in each element like for example C(2)=5, 2 is a local dimension in smaller matrix and 5 is a global dimension in main matrix which is assembled.

If I want to use easy code writing I should use this kind of coding:

%for i=1:size(C,2) for j=1:size(C,2) B(C(i),C(j))=A(i,j)

but I'm trying to use Matlab special features in matrix calculations to put A with local dimension in B with global dimension. because Matlab features are fast and need less code writing.

Note: **A and B are n*n and m*m matrixes.**

*No products are associated with this question.*

Answer by Matt J
on 21 Apr 2013

Accepted answer

B(C,C)=A;

Matt J
on 21 Apr 2013

You're confusing people by writing

%for i=1:size(C,2)

with the '%', as if you have commented this line out. Is there a loop over i or not? If yes, why do you have the '%'? And if i runs from 1 to size(C,2)=4 then A needs to have 4 rows in order for A(i,j) to be accessible when i=4.

Ayob
on 21 Apr 2013

Clear and complete answer by Matt J.

Related Content

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn moreOpportunities for recent engineering grads.

Apply Today
## 3 Comments

## Image Analyst (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/73002#comment_144547

First of all, let's see if this is what you meant (since your code does not run as-is, and I

triedto fix it but am not sure I got what you intended):Results in command window:

## Ayob (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/73002#comment_144554

Yes,you are right.But A and B are both matrixes not vectors.

## Image Analyst (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/73002#comment_144568

Please take note that A

is a 2D 9 by 9 matrix. And B ended up as a 1D row vector because your loop over i only went from 1 to size(C,1), in other words from 1 to 1 so it did just one row. That was your code, not mine, though you commented it out. That's why I asked you if my attempts to fix your code were correct, which you said it was.