Matrix and Array Operations Flashcards

What does `kron(A, B)` compute in MATLAB?

Answer: The Kronecker tensor product of A and B

`kron(A, B)` computes the Kronecker product, replacing each element of A with that scalar times the entire matrix B.

Which MATLAB function computes the rank of a matrix?

Answer: rank(A)

`rank(A)` returns the numerical rank of A, estimated as the number of singular values above a tolerance.

What is the output of `triu([1 2 3; 4 5 6; 7 8 9])`?

Answer: [1 2 3; 0 5 6; 0 0 9]

`triu` returns the upper triangular part of a matrix, keeping elements on and above the main diagonal.

What does `repmat(A, 2, 3)` do to matrix A?

Answer: Tiles A into a 2×3 block grid

`repmat(A, m, n)` replicates A in an m×n tiling pattern to create a larger matrix.

In MATLAB, what does `norm(v)` compute for a vector v by default?

Answer: The L2 norm (Euclidean length)

By default, `norm(v)` computes the 2-norm (Euclidean norm), the square root of the sum of squared elements.

What does `any(A, 2)` return for a matrix A?

Answer: A column vector: true for each row that has at least one nonzero element

`any(A, 2)` operates along dimension 2 (columns), returning a column vector indicating rows with at least one nonzero element.

Which expression correctly extracts the sub-matrix from rows 2–3 and columns 1–2 of a 4×4 matrix A?

Answer: Both A(2:3, 1:2) and A([2,3], [1,2]) work

Both range indexing `2:3` and index vector `[2,3]` select the same rows and columns, so both expressions are equivalent.