version 1.11, 2012/08/22 09:48:19
|
version 1.18, 2018/05/29 06:55:18
|
Line 1
|
Line 1
|
*> \brief \b DLARFG |
*> \brief \b DLARFG generates an elementary reflector (Householder matrix). |
* |
* |
* =========== 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 DLARFG + dependencies |
*> Download DLARFG + dependencies |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarfg.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarfg.f"> |
*> [TGZ]</a> |
*> [TGZ]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarfg.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarfg.f"> |
*> [ZIP]</a> |
*> [ZIP]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarfg.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarfg.f"> |
*> [TXT]</a> |
*> [TXT]</a> |
*> \endhtmlonly |
*> \endhtmlonly |
* |
* |
* Definition: |
* Definition: |
* =========== |
* =========== |
* |
* |
* SUBROUTINE DLARFG( N, ALPHA, X, INCX, TAU ) |
* SUBROUTINE DLARFG( N, ALPHA, X, INCX, TAU ) |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
* INTEGER INCX, N |
* INTEGER INCX, N |
* DOUBLE PRECISION ALPHA, TAU |
* DOUBLE PRECISION ALPHA, TAU |
Line 27
|
Line 27
|
* .. Array Arguments .. |
* .. Array Arguments .. |
* DOUBLE PRECISION X( * ) |
* DOUBLE PRECISION X( * ) |
* .. |
* .. |
* |
* |
* |
* |
*> \par Purpose: |
*> \par Purpose: |
* ============= |
* ============= |
Line 94
|
Line 94
|
* 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 November 2017 |
* |
* |
*> \ingroup doubleOTHERauxiliary |
*> \ingroup doubleOTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
SUBROUTINE DLARFG( N, ALPHA, X, INCX, TAU ) |
SUBROUTINE DLARFG( N, ALPHA, X, INCX, TAU ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.4.0) -- |
* -- LAPACK auxiliary routine (version 3.8.0) -- |
* -- 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 |
* November 2017 |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX, N |
INTEGER INCX, N |
Line 170
|
Line 170
|
CALL DSCAL( N-1, RSAFMN, X, INCX ) |
CALL DSCAL( N-1, RSAFMN, X, INCX ) |
BETA = BETA*RSAFMN |
BETA = BETA*RSAFMN |
ALPHA = ALPHA*RSAFMN |
ALPHA = ALPHA*RSAFMN |
IF( ABS( BETA ).LT.SAFMIN ) |
IF( (ABS( BETA ).LT.SAFMIN) .AND. (KNT .LT. 20) ) |
$ GO TO 10 |
$ GO TO 10 |
* |
* |
* New BETA is at most 1, at least SAFMIN |
* New BETA is at most 1, at least SAFMIN |