dlapmr function

Implementation

void dlapmr(
  final bool FORWRD,
  final int M,
  final int N,
  final Matrix<double> X_,
  final int LDX,
  final Array<int> K,
) {
  final X = X_.having(ld: LDX);
  int I, IN, J, JJ;
  double TEMP;

  if (M <= 1) return;

  for (I = 1; I <= M; I++) {
    K[I] = -K[I];
  }

  if (FORWRD) {
    // Forward permutation

    for (I = 1; I <= M; I++) {
      if (K[I] > 0) continue;

      J = I;
      K[J] = -K[J];
      IN = K[J];

      while (true) {
        if (K[IN] > 0) break;

        for (JJ = 1; JJ <= N; JJ++) {
          TEMP = X[J][JJ];
          X[J][JJ] = X[IN][JJ];
          X[IN][JJ] = TEMP;
        }

        K[IN] = -K[IN];
        J = IN;
        IN = K[IN];
      }
    }
  } else {
    // Backward permutation

    for (I = 1; I <= M; I++) {
      if (K[I] > 0) continue;

      K[I] = -K[I];
      J = K[I];
      while (true) {
        if (J == I) break;

        for (JJ = 1; JJ <= N; JJ++) {
          TEMP = X[I][JJ];
          X[I][JJ] = X[J][JJ];
          X[J][JJ] = TEMP;
        }

        K[J] = -K[J];
        J = K[J];
      }
    }
  }
}