121 SUBROUTINE zpocon( UPLO, N, A, LDA, ANORM, RCOND, WORK, RWORK,
132 DOUBLE PRECISION ANORM, RCOND
135 DOUBLE PRECISION RWORK( * )
136 COMPLEX*16 A( lda, * ), WORK( * )
142 DOUBLE PRECISION ONE, ZERO
143 parameter ( one = 1.0d+0, zero = 0.0d+0 )
149 DOUBLE PRECISION AINVNM, SCALE, SCALEL, SCALEU, SMLNUM
158 DOUBLE PRECISION DLAMCH
159 EXTERNAL lsame, izamax, dlamch
165 INTRINSIC abs, dble, dimag, max
168 DOUBLE PRECISION CABS1
171 cabs1( zdum ) = abs( dble( zdum ) ) + abs( dimag( zdum ) )
178 upper = lsame( uplo,
'U' )
179 IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
181 ELSE IF( n.LT.0 )
THEN
183 ELSE IF( lda.LT.max( 1, n ) )
THEN
185 ELSE IF( anorm.LT.zero )
THEN
189 CALL xerbla(
'ZPOCON', -info )
199 ELSE IF( anorm.EQ.zero )
THEN
203 smlnum = dlamch(
'Safe minimum' )
210 CALL zlacn2( n, work( n+1 ), work, ainvnm, kase, isave )
216 CALL zlatrs(
'Upper',
'Conjugate transpose',
'Non-unit',
217 $ normin, n, a, lda, work, scalel, rwork, info )
222 CALL zlatrs(
'Upper',
'No transpose',
'Non-unit', normin, n,
223 $ a, lda, work, scaleu, rwork, info )
228 CALL zlatrs(
'Lower',
'No transpose',
'Non-unit', normin, n,
229 $ a, lda, work, scalel, rwork, info )
234 CALL zlatrs(
'Lower',
'Conjugate transpose',
'Non-unit',
235 $ normin, n, a, lda, work, scaleu, rwork, info )
240 scale = scalel*scaleu
241 IF( scale.NE.one )
THEN
242 ix = izamax( n, work, 1 )
243 IF( scale.LT.cabs1( work( ix ) )*smlnum .OR. scale.EQ.zero )
245 CALL zdrscl( n, scale, work, 1 )
253 $ rcond = ( one / ainvnm ) / anorm
subroutine zdrscl(N, SA, SX, INCX)
ZDRSCL multiplies a vector by the reciprocal of a real scalar.
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine zlacn2(N, V, X, EST, KASE, ISAVE)
ZLACN2 estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vec...
subroutine zpocon(UPLO, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO)
ZPOCON
subroutine zlatrs(UPLO, TRANS, DIAG, NORMIN, N, A, LDA, X, SCALE, CNORM, INFO)
ZLATRS solves a triangular system of equations with the scale factor set to prevent overflow...