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1 sty 2018 · In MATLAB®, there are three primary approaches to accessing array elements based on their location (index) in the array. These approaches are indexing by position, linear indexing, and logical indexing. You can also use mixed indexing by combining both positional and logical indexing.
Indexing into a matrix is a means of selecting a subset of elements from the matrix. MATLAB has several indexing styles that are not only powerful and flexible, but also readable and expressive. Indexing is a key to MATLAB's effectiveness at capturing matrix-oriented ideas in understandable computer programs.
Convert Linear Indices to Subscripts for Matrix. Convert the linear indices [3 4 5 6] to row and column subscripts in a 3-by-3 matrix. The mapping from linear indices to subscripts (indexing by position) is illustrated in the following. Create input vectors and perform the conversion. ind = [3 4 5 6];
Specify the row, column, and page subscripts in a 2-by-2-by-2 array. Convert the subscripts to linear indices.
[0 1 0 1 1 ] ’ [2 4 5] 2. This means that we can replace any expression involving logical indices by the expression involving regular indices: A(L;M) ’ A(find(L);find(M)) 3. Example: Let L=[0 1 0 1 1] and M = [0 1 0 1]. What is A(L,M)? From 1, we have L ’ [2 4 5] M ’ [2 4] so A(L;M) ’ A([2 4 5];[2 4]) ’ 2 6 6 6 6 4 3 7 7 7 7 5: 3
1 sty 2018 · The sub2ind and ind2sub functions help to convert between original array indices and their linear version. For example, compute the linear index of the 3,2 element of A.
Consider the matrix A = [1 2 3 4;5 6 7 8]. There are actually two ways to view this matrix, either as a rectangular array of 2 rows and 4 columns, or as a list of 8 elements. Suppose we wanted to isolate the 7 in the matrix A and store it as the variable temp.
