O16-070
> restart;
> with(linalg);

  [BlockDiagonal, GramSchmidt, JordanBlock, LUdecomp, QRdecomp,

        Wronskian, addcol, addrow, adj, adjoint, angle, augment,

        backsub, band, basis, bezout, blockmatrix, charmat, charpoly,

        cholesky, col, coldim, colspace, colspan, companion, concat,

        cond, copyinto, crossprod, curl, definite, delcols, delrows,

        det, diag, diverge, dotprod, eigenvals, eigenvalues,

        eigenvectors, eigenvects, entermatrix, equal, exponential,

        extend, ffgausselim, fibonacci, forwardsub, frobenius,

        gausselim, gaussjord, geneqns, genmatrix, grad, hadamard,

        hermite, hessian, hilbert, htranspose, ihermite, indexfunc,

        innerprod, intbasis, inverse, ismith, issimilar, iszero,

        jacobian, jordan, kernel, laplacian, leastsqrs, linsolve,

        matadd, matrix, minor, minpoly, mulcol, mulrow, multiply,

        norm, normalize, nullspace, orthog, permanent, pivot,

        potential, randmatrix, randvector, rank, ratform, row, rowdim,

        rowspace, rowspan, rref, scalarmul, singularvals, smith,

        stackmatrix, submatrix, subvector, sumbasis, swapcol, swaprow,

        sylvester, toeplitz, trace, transpose, vandermonde, vecpotent,

        vectdim, vector, wronskian]

> N:=proc(a)
> sqrt(trace(evalm(transpose(a)&*a))) end;

       N := proc(a) sqrt(trace(evalm(transpose(a) `&*` a))) end

> a:=matrix(4,4,(i,j)->i+j);b:=matrix(4,4,(i,j)->i*j);c:=evalm(a&*b);d:=matrix(4,4,(i,j)->i-j);

                            [2    3    4    5]
                            [                ]
                            [3    4    5    6]
                       a := [                ]
                            [4    5    6    7]
                            [                ]
                            [5    6    7    8]


                           [1    2     3     4]
                           [                  ]
                           [2    4     6     8]
                      b := [                  ]
                           [3    6     9    12]
                           [                  ]
                           [4    8    12    16]


                         [40     80    120    160]
                         [                       ]
                         [50    100    150    200]
                    c := [                       ]
                         [60    120    180    240]
                         [                       ]
                         [70    140    210    280]


                           [0    -1    -2    -3]
                           [                   ]
                           [1     0    -1    -2]
                      d := [                   ]
                           [2     1     0    -1]
                           [                   ]
                           [3     2     1     0]

> N(a),N(b),N(c),N(d);

              2 sqrt(110), 30, 60 sqrt(105), 2 sqrt(10)

>