How to use intersect command with a tolerance value?

I have two vector with different lenght and I want to compare the values of the vectors one by one with a certain tolerance because the numbers are similar but not equal, e.g. 222.456 and 222.389. I was using the command intersect but it only gives me the numbers that are exactly the same.

[madhan ravi]

perhaps ismembertol() ?

Answer 1

[Jan]

While ismembertol might be useful, I'm still puzzled by the way it defines the tolerance.

If the vectors are not too large (some thousand elements should be fine), a simple loop approach should be sufficient:

function [AI, BI] = CommonElemTol(A, B, Tol)
   A  = A(:);
   B  = B(:);
   nA = numel(A);
   M  = zeros(1, nA);
   
   % Collect the index of the first occurrence in B for every A:
   for iA = 1:nA
      dist = abs(A(iA) - B);             % EDITED: Of course abs() is needed
      Ind  = find(dist < Tol, 1);        % Absolute tolerance
      % Ind = find(dist ./ A(iA) < Tol, 1);  % Relative tolerance
      
      if ~isempty(Ind)
         M(iA) = Ind;
      end
   end
   AI = find(M);        % If any occurrence was found, this A exists
   if isempty(AI)       % prevent: Empty matrix: 0-by-1
      AI = [];
   end
   BI = M(AI);          % at this index in B
end

[Vishal Dwivedi]

Thanks.

[Stephen23]

I suspect that

dist = (A(iA) - B);

should be

dist = abs(A(iA) - B);

otherwise there is no absolute involved.

[Jan]

@Stephen: Of course. Thanks.