--- rpl/lapack/lapack/dlansy.f 2012/08/22 09:48:18 1.10 +++ rpl/lapack/lapack/dlansy.f 2020/05/21 21:45:59 1.19 @@ -1,25 +1,25 @@ -*> \brief \b DLANSY +*> \brief \b DLANSY returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix. * * =========== DOCUMENTATION =========== * -* Online html documentation available at -* http://www.netlib.org/lapack/explore-html/ +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ * *> \htmlonly -*> Download DLANSY + dependencies -*> -*> [TGZ] -*> -*> [ZIP] -*> +*> Download DLANSY + dependencies +*> +*> [TGZ] +*> +*> [ZIP] +*> *> [TXT] -*> \endhtmlonly +*> \endhtmlonly * * Definition: * =========== * * DOUBLE PRECISION FUNCTION DLANSY( NORM, UPLO, N, A, LDA, WORK ) -* +* * .. Scalar Arguments .. * CHARACTER NORM, UPLO * INTEGER LDA, N @@ -27,7 +27,7 @@ * .. Array Arguments .. * DOUBLE PRECISION A( LDA, * ), WORK( * ) * .. -* +* * *> \par Purpose: * ============= @@ -110,23 +110,24 @@ * Authors: * ======== * -*> \author Univ. of Tennessee -*> \author Univ. of California Berkeley -*> \author Univ. of Colorado Denver -*> \author NAG Ltd. +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. * -*> \date November 2011 +*> \date December 2016 * *> \ingroup doubleSYauxiliary * * ===================================================================== DOUBLE PRECISION FUNCTION DLANSY( NORM, UPLO, N, A, LDA, WORK ) * -* -- LAPACK auxiliary routine (version 3.4.0) -- +* -- LAPACK auxiliary routine (version 3.7.0) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- -* November 2011 +* December 2016 * + IMPLICIT NONE * .. Scalar Arguments .. CHARACTER NORM, UPLO INTEGER LDA, N @@ -143,17 +144,20 @@ * .. * .. Local Scalars .. INTEGER I, J - DOUBLE PRECISION ABSA, SCALE, SUM, VALUE + DOUBLE PRECISION ABSA, SUM, VALUE * .. -* .. External Subroutines .. - EXTERNAL DLASSQ +* .. Local Arrays .. + DOUBLE PRECISION SSQ( 2 ), COLSSQ( 2 ) * .. * .. External Functions .. - LOGICAL LSAME - EXTERNAL LSAME + LOGICAL LSAME, DISNAN + EXTERNAL LSAME, DISNAN +* .. +* .. External Subroutines .. + EXTERNAL DLASSQ, DCOMBSSQ * .. * .. Intrinsic Functions .. - INTRINSIC ABS, MAX, SQRT + INTRINSIC ABS, SQRT * .. * .. Executable Statements .. * @@ -167,13 +171,15 @@ IF( LSAME( UPLO, 'U' ) ) THEN DO 20 J = 1, N DO 10 I = 1, J - VALUE = MAX( VALUE, ABS( A( I, J ) ) ) + SUM = ABS( A( I, J ) ) + IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM 10 CONTINUE 20 CONTINUE ELSE DO 40 J = 1, N DO 30 I = J, N - VALUE = MAX( VALUE, ABS( A( I, J ) ) ) + SUM = ABS( A( I, J ) ) + IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM 30 CONTINUE 40 CONTINUE END IF @@ -194,7 +200,8 @@ WORK( J ) = SUM + ABS( A( J, J ) ) 60 CONTINUE DO 70 I = 1, N - VALUE = MAX( VALUE, WORK( I ) ) + SUM = WORK( I ) + IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM 70 CONTINUE ELSE DO 80 I = 1, N @@ -207,27 +214,45 @@ SUM = SUM + ABSA WORK( I ) = WORK( I ) + ABSA 90 CONTINUE - VALUE = MAX( VALUE, SUM ) + IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM 100 CONTINUE END IF ELSE IF( ( LSAME( NORM, 'F' ) ) .OR. ( LSAME( NORM, 'E' ) ) ) THEN * * Find normF(A). +* SSQ(1) is scale +* SSQ(2) is sum-of-squares +* For better accuracy, sum each column separately. +* + SSQ( 1 ) = ZERO + SSQ( 2 ) = ONE +* +* Sum off-diagonals * - SCALE = ZERO - SUM = ONE IF( LSAME( UPLO, 'U' ) ) THEN DO 110 J = 2, N - CALL DLASSQ( J-1, A( 1, J ), 1, SCALE, SUM ) + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE + CALL DLASSQ( J-1, A( 1, J ), 1, COLSSQ(1), COLSSQ(2) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) 110 CONTINUE ELSE DO 120 J = 1, N - 1 - CALL DLASSQ( N-J, A( J+1, J ), 1, SCALE, SUM ) + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE + CALL DLASSQ( N-J, A( J+1, J ), 1, COLSSQ(1), COLSSQ(2) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) 120 CONTINUE END IF - SUM = 2*SUM - CALL DLASSQ( N, A, LDA+1, SCALE, SUM ) - VALUE = SCALE*SQRT( SUM ) + SSQ( 2 ) = 2*SSQ( 2 ) +* +* Sum diagonal +* + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE + CALL DLASSQ( N, A, LDA+1, COLSSQ( 1 ), COLSSQ( 2 ) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) + VALUE = SSQ( 1 )*SQRT( SSQ( 2 ) ) END IF * DLANSY = VALUE