fc8c9693b2505b48b1e3dc7c2e477e757d42e549,scipy/sparse/linalg/_onenormest.py,,_algorithm_2_2,#Any#Any#Any#,170

Before Change

        g = sorted(g, reverse=True)
        S = sign_round_up(Y)
        Z = np.asarray(AT_linear_operator.matmat(S))
        h = np.max(np.abs(Z), axis=1)

        // If this algorithm runs for fewer than two iterations,
        // then its return values do not have the properties indicated
        // in the description of the algorithm.
        // In particular, the entries of g are not 1-norms of any
        // column of A until the second iteration.
        // Therefore we will require the algorithm to run for at least
        // two iterations, even though this requirement is not stated
        // in the description of the algorithm.
        if k >= 2:
            if less_than_or_close(max(h), np.dot(Z[:, best_j], X[:, best_j])):
                break
        h_i_pairs = zip(h, range(n))
        h, ind = zip(*sorted(h_i_pairs, reverse=True)[:t])
        for j in range(t):
            X[:, j] = elementary_vector(n, ind[j])

        // Check invariant (2.2).

After Change

        if k >= 2:
            if less_than_or_close(max(h), np.dot(Z[:, best_j], X[:, best_j])):
                break
        ind = np.argsort(h)[::-1][:t]
        h = h[ind]
        for j in range(t):
            X[:, j] = elementary_vector(n, ind[j])

        // Check invariant (2.2).

Instances