def test_matrix_zeros_scipy():
    if not np:
        skip("numpy not installed or Python too old.")
    if not scipy:
        skip("scipy not installed.")

    sci = matrix_zeros(4, 4, format='scipy.sparse')
    assert isinstance(sci, scipy_sparse_matrix)

 def _represent_NumberOp(self, basis, **options):
     ndim_info = options.get('ndim', 4)
     format = options.get('format', 'sympy')
     spmatrix = options.get('spmatrix', 'csr')
     matrix = matrix_zeros(ndim_info, ndim_info, **options)
     for i in range(ndim_info):
         value = i + Integer(1)/Integer(2)
         if format == 'scipy.sparse':
             value = float(value)
         matrix[i,i] = value
     if format == 'scipy.sparse':
         matrix = matrix.tocsr()
     return hbar*omega*matrix

def test_matrix_zeros_numpy():
    if not np:
        skip("numpy not installed or Python too old.")

    num = matrix_zeros(4, 4, format='numpy')
    assert isinstance(num, numpy_ndarray)

def test_matrix_zeros_sympy():
    sym = matrix_zeros(4, 4, format='sympy')
    assert isinstance(sym, Matrix)