True if a matrix is diagonal.
DiagonalMatrixQ[m]
DiagonalMatrixQ[m, k]
DiagonalMatrixQ[{{1, 2}, {0, 3}}]
→ FalseDiagonalMatrixQ[{{0, 1, 0}, {0, 0, 1}, {0, 0, 0}}, 1]
→ TrueDiagonalMatrixQ[{{1, 0, 0}, {0, 2, 0}}]
→ TrueDiagonalMatrixQ[5]
→ False- Tolerance — default Automatic