dqpt01.f3

Usage

Functions/Subroutines

double precision function dqpt01 (m, n, k, a, af, lda, tau, jpvt, work, lwork)
DQPT01

Function/Subroutine Documentation

double precision function dqpt01 (integer m, integer n, integer k, double precision, dimension( lda, * ) a, double precision, dimension( lda, * ) af, integer lda, double precision, dimension( * ) tau, integer, dimension( * ) jpvt, double precision, dimension( lwork ) work, integer lwork)

DQPT01

Purpose:

!>
!> DQPT01 tests the QR-factorization with pivoting of a matrix A.  The
!> array AF contains the (possibly partial) QR-factorization of A, where
!> the upper triangle of AF(1:K,1:K) is a partial triangular factor,
!> the entries below the diagonal in the first K columns are the
!> Householder vectors, and the rest of AF contains a partially updated
!> matrix.
!>
!> This function returns ||A*P - Q*R|| / ( ||norm(A)||*eps*max(M,N) ),
!> where || . || is matrix one norm.
!>

Parameters

!>          M is INTEGER
!>          The number of rows of the matrices A and AF.
!>

!>          N is INTEGER
!>          The number of columns of the matrices A and AF.
!>

!>          K is INTEGER
!>          The number of columns of AF that have been reduced
!>          to upper triangular form.
!>

!>          A is DOUBLE PRECISION array, dimension (LDA, N)
!>          The original matrix A.
!>

!>          AF is DOUBLE PRECISION array, dimension (LDA,N)
!>          The (possibly partial) output of DGEQPF.  The upper triangle
!>          of AF(1:k,1:k) is a partial triangular factor, the entries
!>          below the diagonal in the first k columns are the Householder
!>          vectors, and the rest of AF contains a partially updated
!>          matrix.
!>

LDA

!>          LDA is INTEGER
!>          The leading dimension of the arrays A and AF.
!>

TAU

!>          TAU is DOUBLE PRECISION array, dimension (K)
!>          Details of the Householder transformations as returned by
!>          DGEQPF.
!>

JPVT

!>          JPVT is INTEGER array, dimension (N)
!>          Pivot information as returned by DGEQPF.
!>

WORK

!>          WORK is DOUBLE PRECISION array, dimension (LWORK)
!>

LWORK

!>          LWORK is INTEGER
!>          The length of the array WORK.  LWORK >= M*N+N.
!>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 119 of file dqpt01.f.