--- rpl/lapack/lapack/zlansb.f 2014/01/27 09:28:38 1.13 +++ rpl/lapack/lapack/zlansb.f 2020/05/21 21:46:08 1.18 @@ -2,25 +2,25 @@ * * =========== 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 ZLANSB + dependencies -*> -*> [TGZ] -*> -*> [ZIP] -*> +*> Download ZLANSB + dependencies +*> +*> [TGZ] +*> +*> [ZIP] +*> *> [TXT] -*> \endhtmlonly +*> \endhtmlonly * * Definition: * =========== * * DOUBLE PRECISION FUNCTION ZLANSB( NORM, UPLO, N, K, AB, LDAB, * WORK ) -* +* * .. Scalar Arguments .. * CHARACTER NORM, UPLO * INTEGER K, LDAB, N @@ -29,7 +29,7 @@ * DOUBLE PRECISION WORK( * ) * COMPLEX*16 AB( LDAB, * ) * .. -* +* * *> \par Purpose: * ============= @@ -117,12 +117,12 @@ * 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 September 2012 +*> \date December 2016 * *> \ingroup complex16OTHERauxiliary * @@ -130,11 +130,12 @@ DOUBLE PRECISION FUNCTION ZLANSB( NORM, UPLO, N, K, AB, LDAB, $ WORK ) * -* -- LAPACK auxiliary routine (version 3.4.2) -- +* -- 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..-- -* September 2012 +* December 2016 * + IMPLICIT NONE * .. Scalar Arguments .. CHARACTER NORM, UPLO INTEGER K, LDAB, N @@ -152,14 +153,17 @@ * .. * .. Local Scalars .. INTEGER I, J, L - DOUBLE PRECISION ABSA, SCALE, SUM, VALUE + DOUBLE PRECISION ABSA, SUM, VALUE +* .. +* .. Local Arrays .. + DOUBLE PRECISION SSQ( 2 ), COLSSQ( 2 ) * .. * .. External Functions .. LOGICAL LSAME, DISNAN EXTERNAL LSAME, DISNAN * .. * .. External Subroutines .. - EXTERNAL ZLASSQ + EXTERNAL ZLASSQ, DCOMBSSQ * .. * .. Intrinsic Functions .. INTRINSIC ABS, MAX, MIN, SQRT @@ -227,29 +231,47 @@ 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( K.GT.0 ) THEN IF( LSAME( UPLO, 'U' ) ) THEN DO 110 J = 2, N + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE CALL ZLASSQ( MIN( J-1, K ), AB( MAX( K+2-J, 1 ), J ), - $ 1, SCALE, SUM ) + $ 1, COLSSQ( 1 ), COLSSQ( 2 ) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) 110 CONTINUE L = K + 1 ELSE DO 120 J = 1, N - 1 - CALL ZLASSQ( MIN( N-J, K ), AB( 2, J ), 1, SCALE, - $ SUM ) + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE + CALL ZLASSQ( MIN( N-J, K ), AB( 2, J ), 1, + $ COLSSQ( 1 ), COLSSQ( 2 ) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) 120 CONTINUE L = 1 END IF - SUM = 2*SUM + SSQ( 2 ) = 2*SSQ( 2 ) ELSE L = 1 END IF - CALL ZLASSQ( N, AB( L, 1 ), LDAB, SCALE, SUM ) - VALUE = SCALE*SQRT( SUM ) +* +* Sum diagonal +* + COLSSQ( 1 ) = ZERO + COLSSQ( 2 ) = ONE + CALL ZLASSQ( N, AB( L, 1 ), LDAB, COLSSQ( 1 ), COLSSQ( 2 ) ) + CALL DCOMBSSQ( SSQ, COLSSQ ) + VALUE = SSQ( 1 )*SQRT( SSQ( 2 ) ) END IF * ZLANSB = VALUE