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LAPACK: Linear Algebra PACKage
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dqpt01.f File Reference

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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*M)
Parameters
[in]M
          M is INTEGER
          The number of rows of the matrices A and AF.
[in]N
          N is INTEGER
          The number of columns of the matrices A and AF.
[in]K
          K is INTEGER
          The number of columns of AF that have been reduced
          to upper triangular form.
[in]A
          A is DOUBLE PRECISION array, dimension (LDA, N)
          The original matrix A.
[in]AF
          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.
[in]LDA
          LDA is INTEGER
          The leading dimension of the arrays A and AF.
[in]TAU
          TAU is DOUBLE PRECISION array, dimension (K)
          Details of the Householder transformations as returned by
          DGEQPF.
[in]JPVT
          JPVT is INTEGER array, dimension (N)
          Pivot information as returned by DGEQPF.
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (LWORK)
[in]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.
Date
November 2011

Definition at line 120 of file dqpt01.f.

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