MATLAB: Find elements in a matrix

find

I have a very large matrix A with 4 columns and hundreds of thousands of rows – the first 3 columns contain x, y and z coordinates and the fourth column contains elevation values. I have another smaller matrix B of 3 columns containing x, y and z coordinates at which I need to extract the elevation values from the larger matrix. How do I search for the particular coordinates (given by B) in the larger matrix A? I tried to use 'find' to extract the indices of every match: >> ind=find(B==A(:,1:3))
but I get the error "Matrix dimensions must agree".

Best Answer

[tf idx] = ismember(B,A(:,1:3),'rows')