help understanding simple Vectorization

Hi,

I am new to vectorization and would appreciate if someone could help me vectorize the following;

    for i = 1: length(A)
       idx = A(i,1);
       C(i) = A(i,1)*B(idx);
    end

[Fangjun Jiang]

Please provide an example data. Sometimes the size (of the data) does matter.

Answer 1

[Fangjun Jiang]

C=A(:,1).*B(A(:,1))

[salamay]

for some reason this didnt work for me

[Paulo Silva]

I tried and it gave the same result as your code, like Fangjun said you should provide one example for us to test.

[salamay]

im sorry it works

my syntax was wrong

example

A = [1 2; 1 3; 1 6; 2 2; 2 6; 3 9]

B = [2 5 9]