dgerqs.f - Man Page

subroutine dgerqs (m, n, nrhs, a, lda, tau, b, ldb, work, lwork, info)
DGERQS

DGERQS

Purpose:

 Compute a minimum-norm solution
     min || A*X - B ||
 using the RQ factorization
     A = R*Q
 computed by DGERQF.

Parameters

M

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

N

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

NRHS

          NRHS is INTEGER
          The number of columns of B.  NRHS >= 0.

A

          A is DOUBLE PRECISION array, dimension (LDA,N)
          Details of the RQ factorization of the original matrix A as
          returned by DGERQF.

LDA

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= M.

TAU

          TAU is DOUBLE PRECISION array, dimension (M)
          Details of the orthogonal matrix Q.

B

          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
          On entry, the right hand side vectors for the linear system.
          On exit, the solution vectors X.  Each solution vector
          is contained in rows 1:N of a column of B.

LDB

          LDB is INTEGER
          The leading dimension of the array B. LDB >= max(1,N).

WORK

          WORK is DOUBLE PRECISION array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The length of the array WORK.  LWORK must be at least NRHS,
          and should be at least NRHS*NB, where NB is the block size
          for this environment.

INFO

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

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 120 of file dgerqs.f.