# Find matching indexes in two different size arrays

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Dinu Th. on 26 Apr 2020
Commented: Dinu Th. on 30 Apr 2020
I have two arrays called A and B. I need to to match these two arrays with some tolerence. So that I can get an array like the out put that is given below.(Or any other way to get the index of the column A) Coumns and rows both in B should match with Cs.and Rows in A. As an example 1st column in B matches with the 1st column in A. 2nd column in B matches with the 3rd column in A. Rows should also match like that. Second row in B should match with 4th row in A. You can look at the output array to get an idea. Can someone help with atleast a part of of this quesion? Thank you.
A=[1.414151925 0 0 0 0;
1.731923552 1.224708266 0 0 0;
1.999852844 1.414171143 1.154700414 0 0;
2.236423478 1.581459133 1.291294569 1.118294021 0;
2.828219484 1.999940342 1.632993258 1.414213797 1.26461715]
B=[1.742 0 0;
2.246 1.289 0 ;
2.928 1.6329 1.414]
output= [0 0 0 0 0;
1.731923552 0 0 0 0;
0 0 0 0 0;
2.236423 0 1.291294569 0 0;
2.828219 0 1.632993258 1.414213797 0]

Samatha Aleti on 29 Apr 2020
Edited: Samatha Aleti on 29 Apr 2020
Hi,
As per my understanding you are trying to compare two matrices of different sizes with high tolerance. You can use the function “ismembertol” to do this. This function allows you to specify the tolerance value and compares accordingly.
Here is a piece of code:
output = zeros(size(A)); % Initialize
tol = 0.01; % Tolerance value
comp = ismembertol(A(4,:),B(2,:), tol); % compare 4th row of "A" with 2nd row of "B"
output(4,comp) = A(4,comp) % Assign output value
You can extend this logic for all rows & columns accordingly.
Dinu Th. on 30 Apr 2020
That is not what I want exactly. Because in reality I do not know the matching rows and columns in A. I have B. I need to write a code to search through the array A to find the indices that matches with B. But it should follow that row and column rule that I descibed before. But your answer gave me an idea. Thank you very much.

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