dlasq1(l) [redhat man page]

DLASQ1(l)								 )								 DLASQ1(l)

NAME

       DLASQ1 - compute the singular values of a real N-by-N bidiagonal matrix with diagonal D and off-diagonal E

SYNOPSIS

       SUBROUTINE DLASQ1( N, D, E, WORK, INFO )

	   INTEGER	  INFO, N

	   DOUBLE	  PRECISION D( * ), E( * ), WORK( * )

PURPOSE

       DLASQ1 computes the singular values of a real N-by-N bidiagonal matrix with diagonal D and off-diagonal E. The singular values are computed
       to high relative accuracy, in the absence of denormalization, underflow and overflow. The algorithm was first presented in

       "Accurate singular values and differential qd algorithms" by K. V.  Fernando and B. N. Parlett, Numer. Math., Vol-67, No. 2,  pp.  191-230,
       1994,

       and the present implementation is described in "An implementation of the dqds Algorithm (Positive Case)", LAPACK Working Note.

ARGUMENTS

       N     (input) INTEGER
	     The number of rows and columns in the matrix. N >= 0.

       D     (input/output) DOUBLE PRECISION array, dimension (N)
	     On  entry,  D  contains  the diagonal elements of the bidiagonal matrix whose SVD is desired. On normal exit, D contains the singular
	     values in decreasing order.

       E     (input/output) DOUBLE PRECISION array, dimension (N)
	     On entry, elements E(1:N-1) contain the off-diagonal elements of the bidiagonal matrix whose SVD is desired.  On exit, E is overwrit-
	     ten.

       WORK  (workspace) DOUBLE PRECISION array, dimension (4*N)

       INFO  (output) INTEGER
	     = 0: successful exit
	     < 0: if INFO = -i, the i-th argument had an illegal value
	     > 0: the algorithm failed = 1, a split was marked by a positive value in E = 2, current block of Z not diagonalized after 30*N itera-
	     tions (in inner while loop) = 3, termination criterion of outer while loop not met (program created more than N unreduced blocks)

LAPACK version 3.0						   15 June 2000 							 DLASQ1(l)

slasq1.f(3)							      LAPACK							       slasq1.f(3)

NAME

       slasq1.f -

SYNOPSIS

   Functions/Subroutines
       subroutine slasq1 (N, D, E, WORK, INFO)
	   SLASQ1

Function/Subroutine Documentation
   subroutine slasq1 (integerN, real, dimension( * )D, real, dimension( * )E, real, dimension( * )WORK, integerINFO)
       SLASQ1

       Purpose:

	    SLASQ1 computes the singular values of a real N-by-N bidiagonal
	    matrix with diagonal D and off-diagonal E. The singular values
	    are computed to high relative accuracy, in the absence of
	    denormalization, underflow and overflow. The algorithm was first
	    presented in

	    "Accurate singular values and differential qd algorithms" by K. V.
	    Fernando and B. N. Parlett, Numer. Math., Vol-67, No. 2, pp. 191-230,
	    1994,

	    and the present implementation is described in "An implementation of
	    the dqds Algorithm (Positive Case)", LAPACK Working Note.

       Parameters:
	   N

		     N is INTEGER
		   The number of rows and columns in the matrix. N >= 0.

	   D

		     D is REAL array, dimension (N)
		   On entry, D contains the diagonal elements of the
		   bidiagonal matrix whose SVD is desired. On normal exit,
		   D contains the singular values in decreasing order.

	   E

		     E is REAL array, dimension (N)
		   On entry, elements E(1:N-1) contain the off-diagonal elements
		   of the bidiagonal matrix whose SVD is desired.
		   On exit, E is overwritten.

	   WORK

		     WORK is REAL array, dimension (4*N)

	   INFO

		     INFO is INTEGER
		   = 0: successful exit
		   < 0: if INFO = -i, the i-th argument had an illegal value
		   > 0: the algorithm failed
			= 1, a split was marked by a positive value in E
			= 2, current block of Z not diagonalized after 100*N
			     iterations (in inner while loop)  On exit D and E
			     represent a matrix with the same singular values
			     which the calling subroutine could use to finish the
			     computation, or even feed back into SLASQ1
			= 3, termination criterion of outer while loop not met
			     (program created more than N unreduced blocks)

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 109 of file slasq1.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       slasq1.f(3)