Why does PageRank algorithm return the same scores for all sentences?

Hi Everyone

I am ust doing this code for fun, and I am intereted in automatic text generation and text summarization. I tried to implement a textrank algorithm, as per the website https://www.analyticsvidhya.com/blog/2018/11/introduction-text-summarization-textrank-python/

I rerad in a pdf file using

[file,path] = uigetfile('*.pdf');

I then do some minor cleaning of the sentences

str = lower(extractFileText([path file]));
sentences = splitSentences(str);
sentences = strrep(sentences,'-\n','');
sentences = strrep(sentences,'\n','');
sentences = strrep(sentences,' - ','');
sentences = strrep(sentences,'-','');
nw = 6;
for i = 1:length(sentences)
    s = sentences{i};
    s = strsplit(s,' ');
    if(length(s)>nw)
        l(i) = true;
    end
end
sentences = sentences(l);

I then tokenize the sentences

documents = tokenizedDocument(sentences);
documents = addPartOfSpeechDetails(documents);
documents = removeStopWords(documents);
documents = normalizeWords(documents,'Style','lemma');

And then use word embdedding

emb = fastTextWordEmbedding;
sequences = doc2sequence(emb,documents,'PaddingDirection','none');
for i = 1:length(sequences)
    w(:,i) = mean(sequences{i},2);
end

I then use a cosine simliarity between sentences

for i = 1:length(w)
    for j = 1:length(w)
        if(i~=j)
            sim(i,j) = sum(w(:,i).*w(:,j))./sqrt(sum(w(:,i).^2))./sqrt(sum(w(:,j).^2));
        end
    end
end

And up to this point, I think everything is working, the first 5 rows and columns of the matrx sim lks like this:

ans =

  5×5 single matrix

         0    0.8294    0.8986    0.8466    0.8617
    0.8294         0    0.8337    0.6841    0.8196
    0.8986    0.8337         0    0.7743    0.8096
    0.8466    0.6841    0.7743         0    0.7050
    0.8617    0.8196    0.8096    0.7050         0
    

Finally, I try to fit this sim data into digraph:

    G = digraph(sim);

And finally I run it through the PageRank algo

    pr = centrality(G,'pagerank','FollowProbability',0.85,'MaxIterations',200);

However, when I inspect pr, I get all the same values:

    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    0.0016
    

And I am guessing I do not understand well enough what happens when I convert my matrix to a graph (digraph) or that I do not undertand the inputs into centrality. I have researched what I could be doing wrong, but unfortunately, there seems to be few MATLAB implementations of TextRank.Any help would be greatly appreciated.