dsytri2 function

Implementation

void dsytri2(
  final String UPLO,
  final int N,
  final Matrix<double> A_,
  final int LDA,
  final Array<int> IPIV_,
  final Array<double> WORK_,
  final int LWORK,
  final Box<int> INFO,
) {
  final A = A_.having(ld: LDA);
  final IPIV = IPIV_.having();
  final WORK = WORK_.having();
  bool UPPER, LQUERY;
  int MINSIZE, NBMAX;

  // Test the input parameters.

  INFO.value = 0;
  UPPER = lsame(UPLO, 'U');
  LQUERY = (LWORK == -1);

  // Get blocksize

  NBMAX = ilaenv(1, 'DSYTRI2', UPLO, N, -1, -1, -1);
  if (N == 0) {
    MINSIZE = 1;
  } else if (NBMAX >= N) {
    MINSIZE = N;
  } else {
    MINSIZE = (N + NBMAX + 1) * (NBMAX + 3);
  }

  if (!UPPER && !lsame(UPLO, 'L')) {
    INFO.value = -1;
  } else if (N < 0) {
    INFO.value = -2;
  } else if (LDA < max(1, N)) {
    INFO.value = -4;
  } else if (LWORK < MINSIZE && !LQUERY) {
    INFO.value = -7;
  }

  if (INFO.value != 0) {
    xerbla('DSYTRI2', -INFO.value);
    return;
  } else if (LQUERY) {
    WORK[1] = MINSIZE.toDouble();
    return;
  }

  // Quick return if possible

  if (N == 0) return;

  if (NBMAX >= N) {
    dsytri(UPLO, N, A, LDA, IPIV, WORK, INFO);
  } else {
    dsytri2x(UPLO, N, A, LDA, IPIV, WORK.asMatrix(N), NBMAX, INFO);
  }
}