def normalise_hadamard(H):
    """
    Return the normalised Hadamard matrix corresponding to ``H``.

    The normalised Hadamard matrix corresponding to a Hadamard matrix `H` is a
    matrix whose every entry in the first row and column is +1.

    EXAMPLES::

        sage: H = sage.combinat.matrices.hadamard_matrix.normalise_hadamard(hadamard_matrix(4))
        sage: H == hadamard_matrix(4)
        True
    """
    Hc1 = H.column(0)
    Hr1 = H.row(0)
    for i in range(H.ncols()):
        if Hc1[i] < 0:
            H.rescale_row(i, -1)
    for i in range(H.nrows()):
        if Hr1[i] < 0:
            H.rescale_col(i, -1)
    return H