GEQRT - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T>
void geqrt(integer *m, integer *n, integer *nb, T *a, integer *lda, T *t, integer *ldt, T *work, integer *info)#

GEQRT computes a blocked QR factorization of a M-by-N matrix A

using the compact WY representation.

Purpose:

  GEQRT computes a blocked QR factorization of a M-by-N matrix A
  using the compact WY representation of Q.
Parameters:
  • M[in]

    M is INTEGER

    The number of rows of the matrix A. M >= 0.

  • N[in]

    N is INTEGER

    The number of columns of the matrix A. N >= 0.

  • NB[in]

    NB is INTEGER

    The block size to be used in the blocked QR. MIN(M,N) >= NB >= 1.

  • A[inout]

    A is REAL array, dimension (LDA,N)

    On entry, the M-by-N matrix A.

    On exit, the elements on and above the diagonal of the array contain the min(M,N)-by-N upper trapezoidal matrix R (R is upper triangular if M >= N); the elements below the diagonal are the columns of V.
  • LDA[in]

    LDA is INTEGER

    The leading dimension of the array A. LDA >= fla_max(1,M).

  • T[out]

    T is REAL array, dimension (LDT,MIN(M,N))

    The upper triangular block reflectors stored in compact form as a sequence of upper triangular blocks. See below for further details.

  • LDT[in]

    LDT is INTEGER

    The leading dimension of the array T. LDT >= NB.

  • WORK[out] WORK is COMPLEX array, dimension (NB*N)

  • INFO[out]

    INFO is INTEGER

    = 0: successful exit

    < 0: if INFO = -i, the i-th argument had an illegal value