ORGR2 - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T>
void orgr2(integer *m, integer *n, integer *k, T *a, integer *lda, T *tau, T *work, integer *info)#

ORGR2 generates all or part of the orthogonal matrix Q from an RQ factorization determined by sgerqf.

Purpose:

   ORGR2 generates an m by n real matrix Q with orthonormal rows,
   which is defined as the last m rows of a product of k elementary
   reflectors of order n

         Q  =  H(1) H(2) . . . H(k)

   as   returned by SGERQF.
Parameters:
  • M[in]

    M is INTEGER

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

  • N[in]

    N is INTEGER

    The number of columns of the matrix Q. N >= M.

  • K[in]

    K is INTEGER

    The number of elementary reflectors whose product defines the matrix Q. M >= K >= 0.

  • A[inout]

    A is REAL array, dimension (LDA,N)

    On entry, the (m-k+i)-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,…,k, as returned by SGERQF in the last k rows of its array argument A.

    On exit, the m by n matrix Q.
  • LDA[in]

    LDA is INTEGER

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

  • TAU[in]

    TAU is REAL array, dimension (K)

    TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGERQF.

  • WORK[out] WORK is REAL array, dimension (M)

  • INFO[out]

    INFO is INTEGER

    = 0: successful exit

    < 0: if INFO = -i, the i-th argument has an illegal value
template<typename T>
void ungr2(integer *m, integer *n, integer *k, T *a, integer *lda, T *tau, T *work, integer *info)#