124 SUBROUTINE cgecon( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
139 COMPLEX A( lda, * ), WORK( * )
146 parameter( one = 1.0e+0, zero = 0.0e+0 )
151 INTEGER IX, KASE, KASE1
152 REAL AINVNM, SCALE, SL, SMLNUM, SU
162 EXTERNAL lsame, icamax, slamch
168 INTRINSIC abs, aimag, max, real
174 cabs1( zdum ) = abs(
REAL( ZDUM ) ) + abs( AIMAG( 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(
'CGECON', -info )
202 ELSE IF( anorm.EQ.zero )
THEN
206 smlnum = slamch(
'Safe minimum' )
219 CALL clacn2( n, work( n+1 ), work, ainvnm, kase, isave )
221 IF( kase.EQ.kase1 )
THEN
225 CALL clatrs(
'Lower',
'No transpose',
'Unit', normin, n, a,
226 $ lda, work, sl, rwork, info )
230 CALL clatrs(
'Upper',
'No transpose',
'Non-unit', normin, n,
231 $ a, lda, work, su, rwork( n+1 ), info )
236 CALL clatrs(
'Upper',
'Conjugate transpose',
'Non-unit',
237 $ normin, n, a, lda, work, su, rwork( n+1 ),
242 CALL clatrs(
'Lower',
'Conjugate transpose',
'Unit', normin,
243 $ n, a, lda, work, sl, rwork, info )
250 IF( scale.NE.one )
THEN
251 ix = icamax( n, work, 1 )
252 IF( scale.LT.cabs1( work( ix ) )*smlnum .OR. scale.EQ.zero )
254 CALL csrscl( n, scale, work, 1 )
262 $ rcond = ( one / ainvnm ) / anorm
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine csrscl(N, SA, SX, INCX)
CSRSCL multiplies a vector by the reciprocal of a real scalar.
subroutine clatrs(UPLO, TRANS, DIAG, NORMIN, N, A, LDA, X, SCALE, CNORM, INFO)
CLATRS solves a triangular system of equations with the scale factor set to prevent overflow...
subroutine cgecon(NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO)
CGECON
subroutine clacn2(N, V, X, EST, KASE, ISAVE)
CLACN2 estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vec...