claqps.f(3) LAPACK claqps.f(3)
**NAME**
claqps.f *-
*
**SYNOPSIS**
Functions/Subroutines
subroutine claqps (M, N, OFFSET, NB, KB, A, LDA, JPVT, TAU, VN1, VN2, AUXV, F, LDF)
CLAQPS computes a step of QR factorization with column pivoting of a real m-by-n
matrix A by using BLAS level 3.
**Function**/Subroutine Documentation
subroutine claqps (integerM, integerN, integerOFFSET, integerNB, integerKB, complex,
dimension( lda, * )A, integerLDA, integer, dimension( * )JPVT, complex, dimension( * )TAU,
real, dimension( * )VN1, real, dimension( * )VN2, complex, dimension( * )AUXV, complex,
dimension( ldf, * )F, integerLDF)
CLAQPS computes a step of QR factorization with column pivoting of a real m-by-n matrix A
by using BLAS level 3.
Purpose:
CLAQPS computes a step of QR factorization with column pivoting
of a complex 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.
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 >= 0
OFFSET
OFFSET is INTEGER
The number of rows of A that have been factorized in
previous steps.
NB
NB is INTEGER
The number of columns to factorize.
KB
KB is INTEGER
The number of columns actually factorized.
A
A is COMPLEX 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.
LDA
LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M).
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.
TAU
TAU is COMPLEX array, dimension (KB)
The scalar factors of the elementary reflectors.
VN1
VN1 is REAL array, dimension (N)
The vector with the partial column norms.
VN2
VN2 is REAL array, dimension (N)
The vector with the exact column norms.
AUXV
AUXV is COMPLEX array, dimension (NB)
Auxiliar vector.
F
F is COMPLEX array, dimension (LDF,NB)
Matrix F**H = L * Y**H * A.
LDF
LDF is INTEGER
The leading dimension of the array F. LDF >= max(1,N).
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Contributors:
G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain X. Sun, Computer
Science Dept., Duke University, USA
Partial column norm updating strategy modified on April 2011 Z. Drmac and Z. Bujanovic,
Dept. of Mathematics, University of Zagreb, Croatia.
References:
LAPACK Working Note 176
Definition at line 178 of file claqps.f.
**Author**
Generated automatically by Doxygen for LAPACK from the source code.
**Version 3.4.2** Tue Sep 25 2012 claqps.f(3) |