special.py 文件源码

def _local_add_sparse(ltenss):
    """Computes the local tensors of a sum of MPArrays (except for the boundary
    tensors). Works only for products right now

    :param ltenss: Raveled local tensors
    :returns: Correct local tensor representation

    """
    dim = len(ltenss[0])
    nr_summands = len(ltenss)

    indptr = np.arange(nr_summands * dim + 1)
    indices = np.concatenate((np.arange(nr_summands),) * dim)
    data = np.concatenate([lt[None, :] for lt in ltenss])
    data = np.rollaxis(data, 1).ravel()

    return ssp.csc_matrix((data, indices, indptr),
                          shape=(nr_summands, dim * nr_summands))