version 1.8, 2011/11/21 20:42:59
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version 1.16, 2017/06/17 10:53:57
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*> \brief \b DLASQ1 |
*> \brief \b DLASQ1 computes the singular values of a real square bidiagonal matrix. Used by sbdsqr. |
* |
* |
* =========== DOCUMENTATION =========== |
* =========== DOCUMENTATION =========== |
* |
* |
* Online html documentation available at |
* Online html documentation available at |
* http://www.netlib.org/lapack/explore-html/ |
* http://www.netlib.org/lapack/explore-html/ |
* |
* |
*> \htmlonly |
*> \htmlonly |
*> Download DLASQ1 + dependencies |
*> Download DLASQ1 + dependencies |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasq1.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasq1.f"> |
*> [TGZ]</a> |
*> [TGZ]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasq1.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasq1.f"> |
*> [ZIP]</a> |
*> [ZIP]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasq1.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasq1.f"> |
*> [TXT]</a> |
*> [TXT]</a> |
*> \endhtmlonly |
*> \endhtmlonly |
* |
* |
* Definition: |
* Definition: |
* =========== |
* =========== |
* |
* |
* SUBROUTINE DLASQ1( N, D, E, WORK, INFO ) |
* SUBROUTINE DLASQ1( N, D, E, WORK, INFO ) |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
* INTEGER INFO, N |
* INTEGER INFO, N |
* .. |
* .. |
* .. Array Arguments .. |
* .. Array Arguments .. |
* DOUBLE PRECISION D( * ), E( * ), WORK( * ) |
* DOUBLE PRECISION D( * ), E( * ), WORK( * ) |
* .. |
* .. |
* |
* |
* |
* |
*> \par Purpose: |
*> \par Purpose: |
* ============= |
* ============= |
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*> represent a matrix with the same singular values |
*> represent a matrix with the same singular values |
*> which the calling subroutine could use to finish the |
*> which the calling subroutine could use to finish the |
*> computation, or even feed back into DLASQ1 |
*> computation, or even feed back into DLASQ1 |
*> = 3, termination criterion of outer while loop not met |
*> = 3, termination criterion of outer while loop not met |
*> (program created more than N unreduced blocks) |
*> (program created more than N unreduced blocks) |
*> \endverbatim |
*> \endverbatim |
* |
* |
* Authors: |
* Authors: |
* ======== |
* ======== |
* |
* |
*> \author Univ. of Tennessee |
*> \author Univ. of Tennessee |
*> \author Univ. of California Berkeley |
*> \author Univ. of California Berkeley |
*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
* |
*> \date November 2011 |
*> \date December 2016 |
* |
* |
*> \ingroup auxOTHERcomputational |
*> \ingroup auxOTHERcomputational |
* |
* |
* ===================================================================== |
* ===================================================================== |
SUBROUTINE DLASQ1( N, D, E, WORK, INFO ) |
SUBROUTINE DLASQ1( N, D, E, WORK, INFO ) |
* |
* |
* -- LAPACK computational routine (version 3.4.0) -- |
* -- LAPACK computational routine (version 3.7.0) -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* November 2011 |
* December 2016 |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INFO, N |
INTEGER INFO, N |
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* |
* |
INFO = 0 |
INFO = 0 |
IF( N.LT.0 ) THEN |
IF( N.LT.0 ) THEN |
INFO = -2 |
INFO = -1 |
CALL XERBLA( 'DLASQ1', -INFO ) |
CALL XERBLA( 'DLASQ1', -INFO ) |
RETURN |
RETURN |
ELSE IF( N.EQ.0 ) THEN |
ELSE IF( N.EQ.0 ) THEN |
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CALL DCOPY( N-1, E, 1, WORK( 2 ), 2 ) |
CALL DCOPY( N-1, E, 1, WORK( 2 ), 2 ) |
CALL DLASCL( 'G', 0, 0, SIGMX, SCALE, 2*N-1, 1, WORK, 2*N-1, |
CALL DLASCL( 'G', 0, 0, SIGMX, SCALE, 2*N-1, 1, WORK, 2*N-1, |
$ IINFO ) |
$ IINFO ) |
* |
* |
* Compute the q's and e's. |
* Compute the q's and e's. |
* |
* |
DO 30 I = 1, 2*N - 1 |
DO 30 I = 1, 2*N - 1 |