version 1.8, 2011/11/21 20:42:59
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version 1.13, 2014/01/27 09:28:23
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*> \brief \b DLASSQ |
*> \brief \b DLASSQ updates a sum of squares represented in scaled form. |
* |
* |
* =========== DOCUMENTATION =========== |
* =========== DOCUMENTATION =========== |
* |
* |
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*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
* |
*> \date November 2011 |
*> \date September 2012 |
* |
* |
*> \ingroup auxOTHERauxiliary |
*> \ingroup auxOTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
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 3.4.2) -- |
* -- 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 |
* September 2012 |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX, N |
INTEGER INCX, N |
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INTEGER IX |
INTEGER IX |
DOUBLE PRECISION ABSXI |
DOUBLE PRECISION ABSXI |
* .. |
* .. |
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* .. External Functions .. |
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LOGICAL DISNAN |
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EXTERNAL DISNAN |
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* .. |
* .. 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 |