Loading...
Searching...
No Matches

## sorg2l()

subroutine sorg2l | ( | integer | m,
|  | integer | n,
|  | integer | k,
|  | real, dimension( lda, * ) | a,
|  | integer | lda,
|  | real, dimension( * ) | tau,
|  | real, dimension( * ) | work,
|  | integer | info )

SORG2L generates all or part of the orthogonal matrix Q from a QL factorization determined by sgeqlf (unblocked algorithm).

Download SORG2L + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> SORG2L generates an m by n real matrix Q with orthonormal columns,
      !> which is defined as the last n columns of a product of k elementary
      !> reflectors of order m
      !>
      !>       Q  =  H(k) . . . H(2) H(1)
      !>
      !> as returned by SGEQLF.
      !>

Parameters

  [in]

  M

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

  [in]

  N

      !>          N is INTEGER
      !>          The number of columns of the matrix Q. M >= N >= 0.
      !>

  [in]

  K

      !>          K is INTEGER
      !>          The number of elementary reflectors whose product defines the
      !>          matrix Q. N >= K >= 0.
      !>

  [in,out]

  A

      !>          A is REAL array, dimension (LDA,N)
      !>          On entry, the (n-k+i)-th column must contain the vector which
      !>          defines the elementary reflector H(i), for i = 1,2,...,k, as
      !>          returned by SGEQLF in the last k columns of its array
      !>          argument A.
      !>          On exit, the m by n matrix Q.
      !>

  [in]

  LDA

      !>          LDA is INTEGER
      !>          The first dimension of the array A. LDA >= max(1,M).
      !>

  [in]

  TAU

      !>          TAU is REAL array, dimension (K)
      !>          TAU(i) must contain the scalar factor of the elementary
      !>          reflector H(i), as returned by SGEQLF.
      !>

  [out]

  WORK

      !>          WORK is REAL array, dimension (N)
      !>

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0: successful exit
      !>          < 0: if INFO = -i, the i-th argument has an illegal value
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.