向量化一些matlab代码

Question

我有以下 matlab 代码，我想在没有 for 循环的情况下编写： 该代码将满足特定条件的值分配给稀疏矩阵。 II、JJ为稀疏矩阵索引。

    all_tanh_bits = ones(1, NUMBER_OF_EQ);
    %Calculating each equation multipicative factor.
    for index = 1 : length(II)
        all_tanh_bits(II(index)) = (all_tanh_bits(II(index)) * ...
            tanh(messages_matrix(II(index), JJ(index))/2));
    end

    for index = 1 : length(II)
        %not_relevant_mul is the elemnt to divide - so the
        %current node only uses other message nodes for
        %calculating the llr.
        not_relevant_mul = tanh(messages_matrix(II(index),  ...
                                                JJ(index)) / 2);

        check_matrix_mul = all_tanh_bits(II(index)) / not_relevant_mul;
        check_matrix(II(index), JJ(index)) = ...
            log((1 + check_matrix_mul) / (1 - check_matrix_mul));
    end

Answer 1

第一个 for 循环可以向量化如下。第二个可以类似地完成。

 all_tanh_bits(II) = all_tanh_bits(II) .* tanh(messages_matrix(sub2ind(size(message_matrix), II, JJ))/2);