find negative elements in matrix in matlab

To find the negative elements in a matrix in Matlab, you can use the find command along with the logical indexing. The following code snippet shows how to do it:

main.m
% Example matrix
A = [1 -2 3; -4 5 -6; 7 -8 9];

% Find negative elements using logical indexing
negatives = A(A < 0);

% Alternatively, use find command
[row, col] = find(A < 0);
negative_elements = A(A < 0);
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The first step is to use the logical indexing to extract the negative elements from the matrix. We use the comparison operator < to check if an element is negative or not. The result is a logical matrix of the same size as that of the input matrix A.

In the second step, we use the find command to find the indices of the negative elements in the matrix. The find command returns two output vectors row and col corresponding to the row and column indices of the negative elements. The third output negative_elements is a vector that contains the negative elements in the matrix.

Note that the find command returns the indices of the elements in the matrix in a linear fashion. If you want to get the row-column indices of the negative elements, you need to use ind2sub command.