124 SUBROUTINE zgecon( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
135 DOUBLE PRECISION ANORM, RCOND
138 DOUBLE PRECISION RWORK( * )
139 COMPLEX*16 A( lda, * ), WORK( * )
145 DOUBLE PRECISION ONE, ZERO
146 parameter ( one = 1.0d+0, zero = 0.0d+0 )
151 INTEGER IX, KASE, KASE1
152 DOUBLE PRECISION AINVNM, SCALE, SL, SMLNUM, SU
161 DOUBLE PRECISION DLAMCH
162 EXTERNAL lsame, izamax, dlamch
168 INTRINSIC abs, dble, dimag, max
171 DOUBLE PRECISION CABS1
174 cabs1( zdum ) = abs( dble( zdum ) ) + abs( dimag( zdum ) )
181 onenrm = norm.EQ.
'1' .OR. lsame( norm,
'O' )
182 IF( .NOT.onenrm .AND. .NOT.lsame( norm,
'I' ) )
THEN
184 ELSE IF( n.LT.0 )
THEN
186 ELSE IF( lda.LT.max( 1, n ) )
THEN
188 ELSE IF( anorm.LT.zero )
THEN
192 CALL xerbla(
'ZGECON', -info )
202 ELSE IF( anorm.EQ.zero )
THEN
206 smlnum = dlamch(
'Safe minimum' )
219 CALL zlacn2( n, work( n+1 ), work, ainvnm, kase, isave )
221 IF( kase.EQ.kase1 )
THEN
225 CALL zlatrs(
'Lower',
'No transpose',
'Unit', normin, n, a,
226 $ lda, work, sl, rwork, info )
230 CALL zlatrs(
'Upper',
'No transpose',
'Non-unit', normin, n,
231 $ a, lda, work, su, rwork( n+1 ), info )
236 CALL zlatrs(
'Upper',
'Conjugate transpose',
'Non-unit',
237 $ normin, n, a, lda, work, su, rwork( n+1 ),
242 CALL zlatrs(
'Lower',
'Conjugate transpose',
'Unit', normin,
243 $ n, a, lda, work, sl, rwork, info )
250 IF( scale.NE.one )
THEN
251 ix = izamax( n, work, 1 )
252 IF( scale.LT.cabs1( work( ix ) )*smlnum .OR. scale.EQ.zero )
254 CALL zdrscl( n, scale, work, 1 )
262 $ rcond = ( one / ainvnm ) / anorm
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 zgecon(NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO)
ZGECON
subroutine zdrscl(N, SA, SX, INCX)
ZDRSCL multiplies a vector by the reciprocal of a real scalar.
subroutine xerbla(SRNAME, INFO)
XERBLA
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...