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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)
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