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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| subroutine dlaqps | ( | integer | M, |
| integer | N, | ||
| integer | OFFSET, | ||
| integer | NB, | ||
| integer | KB, | ||
| double precision, dimension( lda, * ) | A, | ||
| integer | LDA, | ||
| integer, dimension( * ) | JPVT, | ||
| double precision, dimension( * ) | TAU, | ||
| double precision, dimension( * ) | VN1, | ||
| double precision, dimension( * ) | VN2, | ||
| double precision, dimension( * ) | AUXV, | ||
| double precision, dimension( ldf, * ) | F, | ||
| integer | LDF | ||
| ) |
DLAQPS computes a step of QR factorization with column pivoting of a real m-by-n matrix A by using BLAS level 3.
Download DLAQPS + dependencies [TGZ] [ZIP] [TXT]
DLAQPS computes a step of QR factorization with column pivoting of a real M-by-N matrix A by using Blas-3. It tries to factorize NB columns from A starting from the row OFFSET+1, and updates all of the matrix with Blas-3 xGEMM. In some cases, due to catastrophic cancellations, it cannot factorize NB columns. Hence, the actual number of factorized columns is returned in KB. Block A(1:OFFSET,1:N) is accordingly pivoted, but not factorized.
| [in] | M | M is INTEGER
The number of rows of the matrix A. M >= 0. |
| [in] | N | N is INTEGER
The number of columns of the matrix A. N >= 0 |
| [in] | OFFSET | OFFSET is INTEGER
The number of rows of A that have been factorized in
previous steps. |
| [in] | NB | NB is INTEGER
The number of columns to factorize. |
| [out] | KB | KB is INTEGER
The number of columns actually factorized. |
| [in,out] | A | A is DOUBLE PRECISION array, dimension (LDA,N)
On entry, the M-by-N matrix A.
On exit, block A(OFFSET+1:M,1:KB) is the triangular
factor obtained and block A(1:OFFSET,1:N) has been
accordingly pivoted, but no factorized.
The rest of the matrix, block A(OFFSET+1:M,KB+1:N) has
been updated. |
| [in] | LDA | LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M). |
| [in,out] | JPVT | JPVT is INTEGER array, dimension (N)
JPVT(I) = K <==> Column K of the full matrix A has been
permuted into position I in AP. |
| [out] | TAU | TAU is DOUBLE PRECISION array, dimension (KB)
The scalar factors of the elementary reflectors. |
| [in,out] | VN1 | VN1 is DOUBLE PRECISION array, dimension (N)
The vector with the partial column norms. |
| [in,out] | VN2 | VN2 is DOUBLE PRECISION array, dimension (N)
The vector with the exact column norms. |
| [in,out] | AUXV | AUXV is DOUBLE PRECISION array, dimension (NB)
Auxiliary vector. |
| [in,out] | F | F is DOUBLE PRECISION array, dimension (LDF,NB)
Matrix F**T = L*Y**T*A. |
| [in] | LDF | LDF is INTEGER
The leading dimension of the array F. LDF >= max(1,N). |
1.9.4