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/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/stpqrt.f(3) Library Functions Manual /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/stpqrt.f(3)

NAME

/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/stpqrt.f

SYNOPSIS

Functions/Subroutines


subroutine STPQRT (m, n, l, nb, a, lda, b, ldb, t, ldt, work, info)
STPQRT

Function/Subroutine Documentation

subroutine STPQRT (integer m, integer n, integer l, integer nb, real, dimension( lda, * ) a, integer lda, real, dimension( ldb, * ) b, integer ldb, real, dimension( ldt, * ) t, integer ldt, real, dimension( * ) work, integer info)

STPQRT

Purpose:

!>
!> STPQRT computes a blocked QR factorization of a real
!>  matrix C, which is composed of a
!> triangular block A and pentagonal block B, using the compact
!> WY representation for Q.
!> 

Parameters

M

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

N

!>          N is INTEGER
!>          The number of columns of the matrix B, and the order of the
!>          triangular matrix A.
!>          N >= 0.
!> 

L

!>          L is INTEGER
!>          The number of rows of the upper trapezoidal part of B.
!>          MIN(M,N) >= L >= 0.  See Further Details.
!> 

NB

!>          NB is INTEGER
!>          The block size to be used in the blocked QR.  N >= NB >= 1.
!> 

A

!>          A is REAL array, dimension (LDA,N)
!>          On entry, the upper triangular N-by-N matrix A.
!>          On exit, the elements on and above the diagonal of the array
!>          contain the upper triangular matrix R.
!> 

LDA

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

B

!>          B is REAL array, dimension (LDB,N)
!>          On entry, the pentagonal M-by-N matrix B.  The first M-L rows
!>          are rectangular, and the last L rows are upper trapezoidal.
!>          On exit, B contains the pentagonal matrix V.  See Further Details.
!> 

LDB

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

T

!>          T is REAL array, dimension (LDT,N)
!>          The upper triangular block reflectors stored in compact form
!>          as a sequence of upper triangular blocks.  See Further Details.
!> 

LDT

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

WORK

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

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.

Further Details:

!>
!>  The input matrix C is a (N+M)-by-N matrix
!>
!>               C = [ A ]
!>                   [ B ]
!>
!>  where A is an upper triangular N-by-N matrix, and B is M-by-N pentagonal
!>  matrix consisting of a (M-L)-by-N rectangular matrix B1 on top of a L-by-N
!>  upper trapezoidal matrix B2:
!>
!>               B = [ B1 ]  <- (M-L)-by-N rectangular
!>                   [ B2 ]  <-     L-by-N upper trapezoidal.
!>
!>  The upper trapezoidal matrix B2 consists of the first L rows of a
!>  N-by-N upper triangular matrix, where 0 <= L <= MIN(M,N).  If L=0,
!>  B is rectangular M-by-N; if M=L=N, B is upper triangular.
!>
!>  The matrix W stores the elementary reflectors H(i) in the i-th column
!>  below the diagonal (of A) in the (N+M)-by-N input matrix C
!>
!>               C = [ A ]  <- upper triangular N-by-N
!>                   [ B ]  <- M-by-N pentagonal
!>
!>  so that W can be represented as
!>
!>               W = [ I ]  <- identity, N-by-N
!>                   [ V ]  <- M-by-N, same form as B.
!>
!>  Thus, all of information needed for W is contained on exit in B, which
!>  we call V above.  Note that V has the same form as B; that is,
!>
!>               V = [ V1 ] <- (M-L)-by-N rectangular
!>                   [ V2 ] <-     L-by-N upper trapezoidal.
!>
!>  The columns of V represent the vectors which define the H(i)'s.
!>
!>  The number of blocks is B = ceiling(N/NB), where each
!>  block is of order NB except for the last block, which is of order
!>  IB = N - (B-1)*NB.  For each of the B blocks, a upper triangular block
!>  reflector factor is computed: T1, T2, ..., TB.  The NB-by-NB (and IB-by-IB
!>  for the last block) T's are stored in the NB-by-N matrix T as
!>
!>               T = [T1 T2 ... TB].
!> 

Definition at line 187 of file stpqrt.f.

Author

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