dimension mismatch error in Matlab

2012 9 20
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Hi everybody,
When i run my program the following error occurs.
"Subscripted assignment dimension mismatch."
I don't know what it means, in particular what it is saying about dimension! i just have some vectors in 1*6 or 3*6.
Looking forward to hearing from you
Best,

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Javier
Javier 2012-9-20
Possible problems.
Vector multiplication error. M(3x1)*N(2x3).
Define break points in the code to search in what line the error occurs.
Hope it helps
Javier
Respaco
Respaco 2012-9-20
Thanks Javier. Actually Matlab shows in which line it has found this error but i can not understand the mistake. It is such a code : A(i,:)=B(1,:);

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Matt Fig
Matt Fig 2012-9-20
编辑：Matt Fig 2012-9-20

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With code like this:
A(i,:)=B(1,:); % Assume i is a scalar...
you need to make sure that:
size(B,2)==size(A,2)
For example:
A = zeros(6,3);
B = magic(3);
TF = size(B,2)==size(A,2) % True, so o.k.
ii = 2;
A(ii,:)=B(1,:); % This works, because TF is 1.
but, this doesn't work:
A = zeros(3,6);
B = magic(3);
TF = size(B,2)==size(A,2) % False, so not o.k.
ii = 2;
A(ii,:)=B(1,:); % This doesn't works, because TF is 0.

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Respaco
Respaco 2012-9-20
Thanks but the number of coloumns for both matrices are the same. Actually when i run my program for 50 to 100 iterations it runs successfully and get me the solution with no error about matrices or sizes but for larger iterations like 1000 the mismatch error occurs. I want to know how it has no error for few iterations? how it really happens?!
thanks
Matt Fig
Matt Fig 2012-9-20
Show the relevant code, because there is something you are leaving out. This works and it goes beyond 1000:
A = zeros(2000,3); % 2000 rows.
B = rand(2000,3);
TF = size(B,2)==size(A,2) % True, so o.k.
for ii = 1:2000,A(ii,:) = B(randi(2000),:);end
Walter Roberson
Walter Roberson 2012-9-20
At the point of error, check to see whether "i" has become a vector.
If it has become a vector, then my crystal ball thinks you might need to read http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

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