MATRIXOPERATIONSThediagonalentriesinan\(m\timesn\)matrix\(A\)(\(a_{ij}\)are\(a_{11},a_{22},a_{33},\dots\)andtheyformthemaindiagonalofA.Adiagonalmatrixisasquarennmatrixwhosenon-diagonalentriesarezero.Anexampl