Vectorization using expressions with matrices

I am trying to vectorize my Matlab code and I am not being able to do that because when I use a value of matrix inside an expression I cannot do that element-by-element. Ok... that was a little bit confusing I will try to explain with some code lines.

Imagine I have to calculate some values using the pre-calculated values contained in a matrix, let's say A. E.g.:

for i=1:100;

    for j=1:100;

      value((i-1)*100+j)=constant*A(i,j);

    end  
  end

This would take a long time, since it is using two for's.

If I try to vectorize this, I would do so:

i=1:100;

j=1:100;

value=constant*A(i,j);

Expecting that the output variable, value, would be a vector. But (you can try yourself), the output will be a [ i x j ] matrix, since the operational logic will not be element-by-element but the combination of the i and j vectores.

Hope that I was unambiguous and that someone can help me.

Thanks a lot in advance!

Kind regards,

Answer 1

[Sean de Wolski]

value2 = constant*(reshape(A',numel(A),1)); %transpose, reshape, multiple
isequal(value,value2)

[Claudio]

Thank you very much!!

Solved my problem :)

Thanks again!