version 1.10, 2012/08/22 09:48:20
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version 1.17, 2018/05/29 07:18:01
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*> \brief \b DLASSQ |
*> \brief \b DLASSQ updates a sum of squares represented in scaled form. |
* |
* |
* =========== 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 DLASSQ + dependencies |
*> Download DLASSQ + dependencies |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlassq.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlassq.f"> |
*> [TGZ]</a> |
*> [TGZ]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlassq.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlassq.f"> |
*> [ZIP]</a> |
*> [ZIP]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlassq.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlassq.f"> |
*> [TXT]</a> |
*> [TXT]</a> |
*> \endhtmlonly |
*> \endhtmlonly |
* |
* |
* Definition: |
* Definition: |
* =========== |
* =========== |
* |
* |
* SUBROUTINE DLASSQ( N, X, INCX, SCALE, SUMSQ ) |
* SUBROUTINE DLASSQ( N, X, INCX, SCALE, SUMSQ ) |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
* INTEGER INCX, N |
* INTEGER INCX, N |
* DOUBLE PRECISION SCALE, SUMSQ |
* DOUBLE PRECISION SCALE, SUMSQ |
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* .. Array Arguments .. |
* .. Array Arguments .. |
* DOUBLE PRECISION X( * ) |
* DOUBLE PRECISION X( * ) |
* .. |
* .. |
* |
* |
* |
* |
*> \par Purpose: |
*> \par Purpose: |
* ============= |
* ============= |
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* 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 auxOTHERauxiliary |
*> \ingroup OTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
SUBROUTINE DLASSQ( N, X, INCX, SCALE, SUMSQ ) |
SUBROUTINE DLASSQ( N, X, INCX, SCALE, SUMSQ ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.4.0) -- |
* -- LAPACK auxiliary 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 INCX, N |
INTEGER INCX, N |
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INTEGER IX |
INTEGER IX |
DOUBLE PRECISION ABSXI |
DOUBLE PRECISION ABSXI |
* .. |
* .. |
|
* .. External Functions .. |
|
LOGICAL DISNAN |
|
EXTERNAL DISNAN |
|
* .. |
* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS |
INTRINSIC ABS |
* .. |
* .. |
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* |
* |
IF( N.GT.0 ) THEN |
IF( N.GT.0 ) THEN |
DO 10 IX = 1, 1 + ( N-1 )*INCX, INCX |
DO 10 IX = 1, 1 + ( N-1 )*INCX, INCX |
IF( X( IX ).NE.ZERO ) THEN |
ABSXI = ABS( X( IX ) ) |
ABSXI = ABS( X( IX ) ) |
IF( ABSXI.GT.ZERO.OR.DISNAN( ABSXI ) ) THEN |
IF( SCALE.LT.ABSXI ) THEN |
IF( SCALE.LT.ABSXI ) THEN |
SUMSQ = 1 + SUMSQ*( SCALE / ABSXI )**2 |
SUMSQ = 1 + SUMSQ*( SCALE / ABSXI )**2 |
SCALE = ABSXI |
SCALE = ABSXI |