Indexing with two matrices

I have two matrices A(1000 by 100) and B(10 by 100).

A=

1 4 20

3 5 15

2 1 24

7 9 42

B=

3 4 15

7 1 42

I want to return a matrix C such that, for each column of B i find the indexes in the coresponding column in A.

For this case:

C=

2 1 2

4 3 4

I have tried the code below, but i am not getting what I want.

for i=1:size(A,2)
    C(:,i)=intersect(A(i),B(i));
end

Answer 1

[KALYAN ACHARJYA]

A=[1    4    20
   3    5    15
   2    1    24
   7    9    42];
B=[3    4    15
   7    1    42];
[r1,c1]=size(B);
c=zeros(r1,c1);
for i=1:r1
for j=1:c1
   r=find(B(i,j)==A(:,j))
   c(i,j)=r
end 
end
c

#

c =
     2     1     2
     4     3     4

[Tchilabalo]

Thanks Kalyan for your answer. The code is working but i have on special case: what if i have one value repeated multiple times in a column? Here is an example:

A=[1 4 20

3 5 15

2 1 24

2 5 15

3 4 15

7 9 42];

B=[3 4 15

7 1 42];

[r1,c1]=size(B);

c=zeros(r1,c1);

[KALYAN ACHARJYA]

but i have on special case: what if i have one value repeated multiple times in a column

The logic, you have to find out, we are here to help you to implementation in MATLAB.

Answer 2

[Stephen23]

>> [C,~] = find(bsxfun(@eq,permute(A,[1,3,2]),permute(B,[3,1,2])));
>> C = reshape(C,size(B))
C =
   2   1   2
   4   3   4

[Tchilabalo]

Thanks Stephen for your answer. It is working now.