117 SUBROUTINE sstev( JOBZ, N, D, E, Z, LDZ, WORK, INFO )
129 REAL D( * ), E( * ), WORK( * ), Z( ldz, * )
136 parameter ( zero = 0.0e0, one = 1.0e0 )
141 REAL BIGNUM, EPS, RMAX, RMIN, SAFMIN, SIGMA, SMLNUM,
147 EXTERNAL lsame, slamch, slanst
159 wantz = lsame( jobz,
'V' )
162 IF( .NOT.( wantz .OR. lsame( jobz,
'N' ) ) )
THEN
164 ELSE IF( n.LT.0 )
THEN
166 ELSE IF( ldz.LT.1 .OR. ( wantz .AND. ldz.LT.n ) )
THEN
171 CALL xerbla(
'SSTEV ', -info )
188 safmin = slamch(
'Safe minimum' )
189 eps = slamch(
'Precision' )
190 smlnum = safmin / eps
191 bignum = one / smlnum
192 rmin = sqrt( smlnum )
193 rmax = sqrt( bignum )
198 tnrm = slanst(
'M', n, d, e )
199 IF( tnrm.GT.zero .AND. tnrm.LT.rmin )
THEN
202 ELSE IF( tnrm.GT.rmax )
THEN
206 IF( iscale.EQ.1 )
THEN
207 CALL sscal( n, sigma, d, 1 )
208 CALL sscal( n-1, sigma, e( 1 ), 1 )
214 IF( .NOT.wantz )
THEN
215 CALL ssterf( n, d, e, info )
217 CALL ssteqr(
'I', n, d, e, z, ldz, work, info )
222 IF( iscale.EQ.1 )
THEN
228 CALL sscal( imax, one / sigma, d, 1 )
subroutine ssteqr(COMPZ, N, D, E, Z, LDZ, WORK, INFO)
SSTEQR
subroutine sstev(JOBZ, N, D, E, Z, LDZ, WORK, INFO)
SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrice...
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine sscal(N, SA, SX, INCX)
SSCAL
subroutine ssterf(N, D, E, INFO)
SSTERF