Loop to perform calculation in C Pagerank

I confess that I can not, at first reading, understand how PageRank works and express it through code. But looking at your attempt to solve, I have identified three potential problems that may be contributing to an incorrect result:

Putting it all together, I suggest changing your code to:

int h=1,g=1; // (Estou mantendo essas linhas iguais,
int j=1,i=1; //  pois elas não importam agora...)
float soma = 0.0, difer= 0.2, max_difer = 0.2; // Variável extra para a diferença máxima

while (max_difer>=0.05) { // Agora compara a diferença máxima
    max_difer = 0.2; // ... resetando ela no início de cada loop
    h = 0; // h também tem de ser resetado, para zero, não para 1

    while (h<numLinhas) { // h vai de 0 a numLinhas-1, então é < e não <=
        soma= 0.0;
        i=pageRank[h].numeroDeLinksRecebe-1; // idem para o i
        while (i>=0) { // i pode ir até zero, então é >= em vez de !=
            g = pageRank[h].quaisLinks[i];
            soma += 0.85 * (pageRank[g].rank/pageRank[g].numeroDeLinksEnviados);
            i--;
        }
        difer = (soma+0.15) - pageRank[h].rank; // Movi pra fora do loop interno

        if ( difer < max_difer ) // Atualiza a diferença máxima
            max_difer = difer;

        pageRank[h].rank=soma+0.15;
        printf("%f ",difer);
        h++;
    }
    j++;
}

I do not know if it will lead to the expected result, but I hope it will be of some help!

Some notes about style:

• Use for when the number of iterations is known in advance, and leave while for when you must reach a condition in an unknown number of steps.

• Declare the variables at the point closest to the point of use, and in the narrowest scope required. Some teachers believe that one must declare the variables in a block at the beginning of the function, a habit that must be abandoned. For example, i is not used outside the h loop, so it's worth declaring it just inside the loop.

• If possible, use C99 or C11, which allows you to for example use the declaration of variables within for .

• Constants in code lose meaning fast. What does 0.85 mean? Of course, you scribbled on a paper to get that value, but that information was not in the code. Consider declaring p = 0.15 within the function, and replacing the places where that value is used.

• By saying a little more about this: there is a joke that is immoral to write a destruir_bagdah() function: the correct thing is to do a destruir(cidade) function and then pass Baghdad as a parameter. In your case, consider that PageRank might work with other values of p desired, so that it should come from outside.

Quite possibly, the problem with your code is that you're changing the array of ranks as you go through it. You need to make a copy of the structure in order to change the new one.

This is evident if you see the calculation of PageRank as an iteration of matrix multiplication. If A is the matrix that gives the links, where A[i][j] = 1 if the page i has a link to page j , and v is the ranks vector, then PageRank is obtained iterating

v_novo = A * v_prev + v_aleatório

until v_prev ~ v_novo . I have not tested the following program, but I hope it is correct. Next time, consider easing the work of those who respond, many times only in the effort to create a minimal example you solve the problem.

// Nao precisa colocar o tipo de pageRank como struct page, vc ja
// fez um typedef
void calculoPageRank(page *pageRank, int numLinhas){    
    // Se nao tem motivo pra usar float, use double, que eh mais preciso
    double p = 0.15;
    double soma = 0.0, difer= 0.2; 

    int contador = 0; // j nao parecia um bom nome pra essa variavel
    while (difer >= 0.05) {
        page copia[numLinhas]; //C99 - se nao funcionar, use copia[80]

        // memcpy copia pedacos de memoria. Necessita do header <string.h>
        memcpy(copia, pageRank, numLinhas * sizeof(page));

        for (int h = 1; h <= numLinhas; h++) {
            soma= 0.0;
            int i = copia[h].numeroDeLinksRecebe;
            for (; i > 0; i--) {
                int g = copia[h].quaisLinks[i];
                soma += (1 - p) * (copia[g].rank / copia[g].numeroDeLinksEnviados);
                difer = (soma + p) - copia[h].rank;
            }

            pageRank[h].rank = soma + p;
            printf("%f ",difer);
        }
        contador++; // Pra que voce esta usando isso?
    }
}