debian man page for slaqps

slaqps.f(3)							      LAPACK							       slaqps.f(3)

NAME
       slaqps.f -

SYNOPSIS
   Functions/Subroutines
       subroutine slaqps (M, N, OFFSET, NB, KB, A, LDA, JPVT, TAU, VN1, VN2, AUXV, F, LDF)
	   SLAQPS

Function/Subroutine Documentation
   subroutine slaqps (integerM, integerN, integerOFFSET, integerNB, integerKB, real, dimension( lda, * )A, integerLDA, integer, dimension( *
       )JPVT, real, dimension( * )TAU, real, dimension( * )VN1, real, dimension( * )VN2, real, dimension( * )AUXV, real, dimension( ldf, * )F,
       integerLDF)
       SLAQPS

       Purpose:

	    SLAQPS 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.

       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 REAL 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 REAL 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 REAL array, dimension (NB)
		     Auxiliar vector.

	   F

		     F is REAL array, dimension (LDF,NB)
		     Matrix F**T = L*Y**T*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:
	   November 2011

       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 slaqps.f.

Author
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Version 3.4.1							  Sun May 26 2013						       slaqps.f(3)