コード例 #1
0
ファイル: VeryLong.cpp プロジェクト: TrainingAccount/Crypto_3
Verylong operator* (const Verylong &u, const Verylong &v)
{
	Verylong pprod("1"), tempsum("0");

	for (int j=0; j<v.vlen; j++)
	{
		int digit = v.vlstr[j] - '0';
		pprod = u.multdigit(digit);
		pprod = pprod.mult10(j);

		tempsum += pprod;
	}

	tempsum.vlsign = u.vlsign ^ v.vlsign;
	return tempsum;
}
コード例 #2
0
ファイル: Estep.cpp プロジェクト: jacobxk/mirt
void _Estepbfactor(vector<double> &expected, vector<double> &r1, vector<double> &ri,
    const NumericMatrix &itemtrace, const vector<double> &prior, const vector<double> &Priorbetween, 
    const vector<int> &r, const int &ncores, const IntegerMatrix &data, const IntegerMatrix &sitems,
    const vector<double> &Prior)
{
     #ifdef SUPPORT_OPENMP
    omp_set_num_threads(ncores);
    #endif
    const int sfact = sitems.ncol();
    const int nitems = data.ncol();
    const int npquad = prior.size();
    const int nbquad = Priorbetween.size();
    const int nquad = nbquad * npquad;
    const int npat = r.size();
    vector<double> r1vec(nquad*nitems*sfact, 0.0);

#pragma omp parallel for
    for (int pat = 0; pat < npat; ++pat){
        vector<double> L(nquad), Elk(nbquad*sfact), posterior(nquad*sfact);
        vector<double> likelihoods(nquad*sfact, 1.0);
        for (int fact = 0; fact < sfact; ++fact){
            for (int item = 0; item < nitems; ++item){
                if (data(pat,item) && sitems(item,fact))
                    for (int k = 0; k < nquad; ++k)
                        likelihoods[k + nquad*fact] = likelihoods[k + nquad*fact] * itemtrace(k,item);
            }
        }
        vector<double> Plk(nbquad*sfact);
        for (int fact = 0; fact < sfact; ++fact){
            int k = 0;
            for (int q = 0; q < npquad; ++q){
                for (int i = 0; i < nbquad; ++i){
                    L[k] = likelihoods[k + nquad*fact] * prior[q];
                    ++k;
                }
            }
            vector<double> tempsum(nbquad, 0.0);
            for (int i = 0; i < npquad; ++i)
                for (int q = 0; q < nbquad; ++q)
                    tempsum[q] += L[q + i*nbquad];
            for (int i = 0; i < nbquad; ++i)
                Plk[i + fact*nbquad] = tempsum[i];
        }
        vector<double> Pls(nbquad, 1.0);
        for (int i = 0; i < nbquad; ++i){
            for(int fact = 0; fact < sfact; ++fact)
                Pls[i] = Pls[i] * Plk[i + fact*nbquad];
            expected[pat] += Pls[i] * Priorbetween[i];
        }
        for (int fact = 0; fact < sfact; ++fact)
            for (int i = 0; i < nbquad; ++i)
                Elk[i + fact*nbquad] = Pls[i] / Plk[i + fact*nbquad];
        for (int fact = 0; fact < sfact; ++fact)
            for (int i = 0; i < nquad; ++i)
                posterior[i + nquad*fact] = likelihoods[i + nquad*fact] * r[pat] * Elk[i % nbquad + fact*nbquad] /
                                            expected[pat];
        #pragma omp critical
        for (int i = 0; i < nbquad; ++i)
            ri[i] += Pls[i] * r[pat] * Priorbetween[i] / expected[pat];
        for (int item = 0; item < nitems; ++item)
            if (data(pat,item))
                for (int fact = 0; fact < sfact; ++fact)
                    for(int q = 0; q < nquad; ++q)
                        r1vec[q + fact*nquad*nitems + nquad*item] += posterior[q + fact*nquad];
    }   //end main
    for (int item = 0; item < nitems; ++item)
        for (int fact = 0; fact < sfact; ++fact)
            if(sitems(item, fact))
                for(int q = 0; q < nquad; ++q)
                    r1[q + nquad*item] = r1vec[q + nquad*item + nquad*nitems*fact] * Prior[q];
}
コード例 #3
0
bool Reed_Solomon::decode(const bvec &coded_bits, const ivec &erasure_positions, bvec &decoded_message, bvec &cw_isvalid)
{
  bool decoderfailure, no_dec_failure;
  int j, i, kk, l, L, foundzeros, iterations = floor_i(static_cast<double>(coded_bits.length()) / (n * m));
  bvec mbit(m * k);
  decoded_message.set_size(iterations * k * m, false);
  cw_isvalid.set_length(iterations);

  GFX rx(q, n - 1), cx(q, n - 1), mx(q, k - 1), ex(q, n - 1), S(q, 2 * t), Xi(q, 2 * t), Gamma(q), Lambda(q),
      Psiprime(q), OldLambda(q), T(q), Omega(q);
  GFX dummy(q), One(q, (char*)"0"), Omegatemp(q);
  GF delta(q), tempsum(q), rtemp(q), temp(q), Xk(q), Xkinv(q);
  ivec errorpos;

  if ( erasure_positions.length() ) {
    it_assert(max(erasure_positions) < iterations*n, "Reed_Solomon::decode: erasure position is invalid.");
  }
  
  no_dec_failure = true;
  for (i = 0; i < iterations; i++) {
    decoderfailure = false;
    //Fix the received polynomial r(x)
    for (j = 0; j < n; j++) {
      rtemp.set(q, coded_bits.mid(i * n * m + j * m, m));
      rx[j] = rtemp;
    }
    // Fix the Erasure polynomial Gamma(x)
    // and replace erased coordinates with zeros
    rtemp.set(q, -1);
    ivec alphapow = - ones_i(2);
    Gamma = One;
    for (j = 0; j < erasure_positions.length(); j++) {
      rx[erasure_positions(j)] = rtemp;
      alphapow(1) = erasure_positions(j);
      Gamma *= (One - GFX(q, alphapow));
    }
    //Fix the syndrome polynomial S(x).
    S.clear();
    for (j = 1; j <= 2 * t; j++) {
      S[j] = rx(GF(q, b + j - 1));
    }
    // calculate the modified syndrome polynomial Xi(x) = Gamma * (1+S) - 1
    Xi = Gamma * (One + S) - One;
    // Apply Berlekam-Massey algorithm
    if (Xi.get_true_degree() >= 1) { //Errors in the received word
      // Iterate to find Lambda(x), which hold all error locations
      kk = 0;
      Lambda = One;
      L = 0;
      T = GFX(q, (char*)"-1 0");
      while (kk < 2 * t) {
        kk = kk + 1;
        tempsum = GF(q, -1);
        for (l = 1; l <= L; l++) {
          tempsum += Lambda[l] * Xi[kk - l];
        }
        delta = Xi[kk] - tempsum;
        if (delta != GF(q, -1)) {
          OldLambda = Lambda;
          Lambda -= delta * T;
          if (2 * L < kk) {
            L = kk - L;
            T = OldLambda / delta;
          }
        }
        T = GFX(q, (char*)"-1 0") * T;
      }
      // Find the zeros to Lambda(x)
      errorpos.set_size(Lambda.get_true_degree());
      foundzeros = 0;
      for (j = q - 2; j >= 0; j--) {
        if (Lambda(GF(q, j)) == GF(q, -1)) {
          errorpos(foundzeros) = (n - j) % n;
          foundzeros += 1;
          if (foundzeros >= Lambda.get_true_degree()) {
            break;
          }
        }
      }
      if (foundzeros != Lambda.get_true_degree()) {
        decoderfailure = true;
      }
      else { // Forney algorithm...
        //Compute Omega(x) using the key equation for RS-decoding
        Omega.set_degree(2 * t);
        Omegatemp = Lambda * (One + Xi);
        for (j = 0; j <= 2 * t; j++) {
          Omega[j] = Omegatemp[j];
        }
        //Find the error/erasure magnitude polynomial by treating them the same
        Psiprime = formal_derivate(Lambda*Gamma);
        errorpos = concat(errorpos, erasure_positions);
        ex.clear();
        for (j = 0; j < errorpos.length(); j++) {
          Xk = GF(q, errorpos(j));
          Xkinv = GF(q, 0) / Xk;
          // we calculate ex = - error polynomial, in order to avoid the 
          // subtraction when recunstructing the corrected codeword
          ex[errorpos(j)] = (Xk * Omega(Xkinv)) / Psiprime(Xkinv);
          if (b != 1) { // non-narrow-sense code needs corrected error magnitudes
            int correction_exp = ( errorpos(j)*(1-b) ) % n;
            ex[errorpos(j)] *= GF(q, correction_exp + ( (correction_exp < 0) ? n : 0 ));
          }
        }
        //Reconstruct the corrected codeword.
        // instead of subtracting the error/erasures, we calculated 
        // the negative error with 'ex' above
        cx = rx + ex;
        //Code word validation
        S.clear();
        for (j = 1; j <= 2 * t; j++) {
          S[j] = cx(GF(q, b + j - 1));
        }
        if (S.get_true_degree() >= 1) {
          decoderfailure = true;
        }
      }
    }
    else {
      cx = rx;
      decoderfailure = false;
    }
    //Find the message polynomial
    mbit.clear();
    if (decoderfailure == false) {
      if (cx.get_true_degree() >= 1) { // A nonzero codeword was transmitted
        if (systematic) {
          for (j = 0; j < k; j++) {
            mx[j] = cx[j];
          }
        }
        else {
          mx = divgfx(cx, g);
        }
        for (j = 0; j <= mx.get_true_degree(); j++) {
          mbit.replace_mid(j * m, mx[j].get_vectorspace());
        }
      }
    }
    else { //Decoder failure.
      // for a systematic code it is better to extract the undecoded message
      // from the received code word, i.e. obtaining a bit error
      // prob. p_b << 1/2, than setting all-zero (p_b = 1/2)
      if (systematic) {
        mbit = coded_bits.mid(i * n * m, k * m);
      }
      else {
        mbit = zeros_b(k);
      }
      no_dec_failure = false;
    }
    decoded_message.replace_mid(i * m * k, mbit);
    cw_isvalid(i) = (!decoderfailure);
  }
  return no_dec_failure;
}