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A.6 Cofactor Expansion Tool

When working with determinants by cofactor expansion, having a tool to quickly produce the minors of a matrix is invaluable.

The minor function code

function myMatrix  = minor(A,i,j)
    % Input Validation
    arguments
        A (:,:,:)
        i (1,1) {mustBeInteger, mustBePositive}
        j (1,1) {mustBeInteger, mustBePositive}
    end

% Delete row i
A(i,:) = [];

% Delete colun j
A(:,j) = [];

% Assign result to cofactor matrix
myMatrix = A;
end

Breaking down the sections

We force the user to input a matrix and ask what row and column to delete.

    arguments
        A (:,:,:)
        i (1,1) {mustBeInteger, mustBePositive}
        j (1,1) {mustBeInteger, mustBePositive}
    end

We delete row \(i\) and column \(j\) in turn by setting them equal to an empty matrix.

A(i,:) = [];

A(:,j) = [];

We return the deleted matrix \(A\) as the output of the function.

myMatrix = A;

A.5 Timesaver