.TH "SRC/claqps.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/claqps.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBclaqps\fP (m, n, offset, nb, kb, a, lda, jpvt, tau, vn1, vn2, auxv, f, ldf)"
.br
.RI "\fBCLAQPS\fP computes a step of QR factorization with column pivoting of a real m-by-n matrix A by using BLAS level 3\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine claqps (integer m, integer n, integer offset, integer nb, integer kb, complex, dimension( lda, * ) a, integer lda, integer, dimension( * ) jpvt, complex, dimension( * ) tau, real, dimension( * ) vn1, real, dimension( * ) vn2, complex, dimension( * ) auxv, complex, dimension( ldf, * ) f, integer ldf)"

.PP
\fBCLAQPS\fP computes a step of QR factorization with column pivoting of a real m-by-n matrix A by using BLAS level 3\&.  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> 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\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIM\fP 
.PP
.nf
!>          M is INTEGER
!>          The number of rows of the matrix A\&. M >= 0\&.
!> 
.fi
.PP
.br
\fIN\fP 
.PP
.nf
!>          N is INTEGER
!>          The number of columns of the matrix A\&. N >= 0
!> 
.fi
.PP
.br
\fIOFFSET\fP 
.PP
.nf
!>          OFFSET is INTEGER
!>          The number of rows of A that have been factorized in
!>          previous steps\&.
!> 
.fi
.PP
.br
\fINB\fP 
.PP
.nf
!>          NB is INTEGER
!>          The number of columns to factorize\&.
!> 
.fi
.PP
.br
\fIKB\fP 
.PP
.nf
!>          KB is INTEGER
!>          The number of columns actually factorized\&.
!> 
.fi
.PP
.br
\fIA\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fILDA\fP 
.PP
.nf
!>          LDA is INTEGER
!>          The leading dimension of the array A\&. LDA >= max(1,M)\&.
!> 
.fi
.PP
.br
\fIJPVT\fP 
.PP
.nf
!>          JPVT is INTEGER array, dimension (N)
!>          JPVT(I) = K <==> Column K of the full matrix A has been
!>          permuted into position I in AP\&.
!> 
.fi
.PP
.br
\fITAU\fP 
.PP
.nf
!>          TAU is COMPLEX array, dimension (KB)
!>          The scalar factors of the elementary reflectors\&.
!> 
.fi
.PP
.br
\fIVN1\fP 
.PP
.nf
!>          VN1 is REAL array, dimension (N)
!>          The vector with the partial column norms\&.
!> 
.fi
.PP
.br
\fIVN2\fP 
.PP
.nf
!>          VN2 is REAL array, dimension (N)
!>          The vector with the exact column norms\&.
!> 
.fi
.PP
.br
\fIAUXV\fP 
.PP
.nf
!>          AUXV is COMPLEX array, dimension (NB)
!>          Auxiliary vector\&.
!> 
.fi
.PP
.br
\fIF\fP 
.PP
.nf
!>          F is COMPLEX array, dimension (LDF,NB)
!>          Matrix  F**H = L * Y**H * A\&.
!> 
.fi
.PP
.br
\fILDF\fP 
.PP
.nf
!>          LDF is INTEGER
!>          The leading dimension of the array F\&. LDF >= max(1,N)\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
.PP
\fBContributors:\fP
.RS 4
G\&. Quintana-Orti, Depto\&. de Informatica, Universidad Jaime I, Spain X\&. Sun, Computer Science Dept\&., Duke University, USA
.RE
.PP

.br
 Partial column norm updating strategy modified on April 2011 Z\&. Drmac and Z\&. Bujanovic, Dept\&. of Mathematics, University of Zagreb, Croatia\&. 
.PP
\fBReferences:\fP
.RS 4
LAPACK Working Note 176  
.RE
.PP

.PP
Definition at line \fB176\fP of file \fBclaqps\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.