CODEWITHSUNDEEP
matlab
yaron
yaron

Reputation: 117

How to write this matlab code without a for loop

I have the following matlab code:

    messages_llr_matrix = sparse(ROW_NUM, COL_NUM);
    for index = 1 : length(II)
        messages_llr_matrix(II(index), JJ(index)) = ...
        code_word_aprior_prob(JJ(index));
    end

This code takes a vector and copies it, to a sparse matrix rows if the element in the matrix is not zero.

matlab tells me not to use indexing in the previous matlab code, because it makes it very slow. I want to build the messages_llr_matrix matrix in the following manner:

messages_llr_matrix = sparse(II,JJ,code_word_aprior_prob,ROW_NUM,COL_NUM);

This is not a solution that works.

Upvotes: 0

Views: 65

Answers (1)

Andras Deak -- Слава Україні
Andras Deak -- Слава Україні

Reputation: 35175

The problem seems to be that in your latter code II(ind), JJ(ind) and code_word_aprior_prob(ind) should go together, but in your convention you need code_word_aprior_prob(JJ(ind)).

Try calling

messages_llr_matrix = sparse(II,JJ,code_word_aprior_prob(JJ),ROW_NUM,COL_NUM);

Upvotes: 2

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