version 1.18, 2020/05/21 21:45:59
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version 1.19, 2023/08/07 08:38:55
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*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
* |
*> \date December 2016 |
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* |
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*> \ingroup doubleOTHERauxiliary |
*> \ingroup doubleOTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
DOUBLE PRECISION FUNCTION DLANSB( NORM, UPLO, N, K, AB, LDAB, |
DOUBLE PRECISION FUNCTION DLANSB( NORM, UPLO, N, K, AB, LDAB, |
$ WORK ) |
$ WORK ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.7.0) -- |
* -- LAPACK auxiliary routine -- |
* -- 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..-- |
* December 2016 |
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* |
* |
IMPLICIT NONE |
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* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
CHARACTER NORM, UPLO |
CHARACTER NORM, UPLO |
INTEGER K, LDAB, N |
INTEGER K, LDAB, N |
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* .. |
* .. |
* .. Local Scalars .. |
* .. Local Scalars .. |
INTEGER I, J, L |
INTEGER I, J, L |
DOUBLE PRECISION ABSA, SUM, VALUE |
DOUBLE PRECISION ABSA, SCALE, SUM, VALUE |
* .. |
* .. |
* .. Local Arrays .. |
* .. External Subroutines .. |
DOUBLE PRECISION SSQ( 2 ), COLSSQ( 2 ) |
EXTERNAL DLASSQ |
* .. |
* .. |
* .. External Functions .. |
* .. External Functions .. |
LOGICAL LSAME, DISNAN |
LOGICAL LSAME, DISNAN |
EXTERNAL LSAME, DISNAN |
EXTERNAL LSAME, DISNAN |
* .. |
* .. |
* .. External Subroutines .. |
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EXTERNAL DLASSQ, DCOMBSSQ |
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* .. |
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* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS, MAX, MIN, SQRT |
INTRINSIC ABS, MAX, MIN, SQRT |
* .. |
* .. |
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ELSE IF( ( LSAME( NORM, 'F' ) ) .OR. ( LSAME( NORM, 'E' ) ) ) THEN |
ELSE IF( ( LSAME( NORM, 'F' ) ) .OR. ( LSAME( NORM, 'E' ) ) ) THEN |
* |
* |
* Find normF(A). |
* Find normF(A). |
* SSQ(1) is scale |
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* SSQ(2) is sum-of-squares |
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* For better accuracy, sum each column separately. |
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* |
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SSQ( 1 ) = ZERO |
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SSQ( 2 ) = ONE |
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* |
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* Sum off-diagonals |
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* |
* |
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SCALE = ZERO |
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SUM = ONE |
IF( K.GT.0 ) THEN |
IF( K.GT.0 ) THEN |
IF( LSAME( UPLO, 'U' ) ) THEN |
IF( LSAME( UPLO, 'U' ) ) THEN |
DO 110 J = 2, N |
DO 110 J = 2, N |
COLSSQ( 1 ) = ZERO |
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COLSSQ( 2 ) = ONE |
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CALL DLASSQ( MIN( J-1, K ), AB( MAX( K+2-J, 1 ), J ), |
CALL DLASSQ( MIN( J-1, K ), AB( MAX( K+2-J, 1 ), J ), |
$ 1, COLSSQ( 1 ), COLSSQ( 2 ) ) |
$ 1, SCALE, SUM ) |
CALL DCOMBSSQ( SSQ, COLSSQ ) |
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110 CONTINUE |
110 CONTINUE |
L = K + 1 |
L = K + 1 |
ELSE |
ELSE |
DO 120 J = 1, N - 1 |
DO 120 J = 1, N - 1 |
COLSSQ( 1 ) = ZERO |
CALL DLASSQ( MIN( N-J, K ), AB( 2, J ), 1, SCALE, |
COLSSQ( 2 ) = ONE |
$ SUM ) |
CALL DLASSQ( MIN( N-J, K ), AB( 2, J ), 1, |
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$ COLSSQ( 1 ), COLSSQ( 2 ) ) |
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CALL DCOMBSSQ( SSQ, COLSSQ ) |
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120 CONTINUE |
120 CONTINUE |
L = 1 |
L = 1 |
END IF |
END IF |
SSQ( 2 ) = 2*SSQ( 2 ) |
SUM = 2*SUM |
ELSE |
ELSE |
L = 1 |
L = 1 |
END IF |
END IF |
* |
CALL DLASSQ( N, AB( L, 1 ), LDAB, SCALE, SUM ) |
* Sum diagonal |
VALUE = SCALE*SQRT( SUM ) |
* |
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COLSSQ( 1 ) = ZERO |
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COLSSQ( 2 ) = ONE |
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CALL DLASSQ( N, AB( L, 1 ), LDAB, COLSSQ( 1 ), COLSSQ( 2 ) ) |
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CALL DCOMBSSQ( SSQ, COLSSQ ) |
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VALUE = SSQ( 1 )*SQRT( SSQ( 2 ) ) |
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END IF |
END IF |
* |
* |
DLANSB = VALUE |
DLANSB = VALUE |