140 SUBROUTINE zheev( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, RWORK,
150 INTEGER INFO, LDA, LWORK, N
153 DOUBLE PRECISION RWORK( * ), W( * )
154 COMPLEX*16 A( lda, * ), WORK( * )
160 DOUBLE PRECISION ZERO, ONE
161 parameter ( zero = 0.0d0, one = 1.0d0 )
163 parameter ( cone = ( 1.0d0, 0.0d0 ) )
166 LOGICAL LOWER, LQUERY, WANTZ
167 INTEGER IINFO, IMAX, INDE, INDTAU, INDWRK, ISCALE,
169 DOUBLE PRECISION ANRM, BIGNUM, EPS, RMAX, RMIN, SAFMIN, SIGMA,
175 DOUBLE PRECISION DLAMCH, ZLANHE
176 EXTERNAL lsame, ilaenv, dlamch, zlanhe
189 wantz = lsame( jobz,
'V' )
190 lower = lsame( uplo,
'L' )
191 lquery = ( lwork.EQ.-1 )
194 IF( .NOT.( wantz .OR. lsame( jobz,
'N' ) ) )
THEN
196 ELSE IF( .NOT.( lower .OR. lsame( uplo,
'U' ) ) )
THEN
198 ELSE IF( n.LT.0 )
THEN
200 ELSE IF( lda.LT.max( 1, n ) )
THEN
205 nb = ilaenv( 1,
'ZHETRD', uplo, n, -1, -1, -1 )
206 lwkopt = max( 1, ( nb+1 )*n )
209 IF( lwork.LT.max( 1, 2*n-1 ) .AND. .NOT.lquery )
214 CALL xerbla(
'ZHEEV ', -info )
216 ELSE IF( lquery )
THEN
236 safmin = dlamch(
'Safe minimum' )
237 eps = dlamch(
'Precision' )
238 smlnum = safmin / eps
239 bignum = one / smlnum
240 rmin = sqrt( smlnum )
241 rmax = sqrt( bignum )
245 anrm = zlanhe(
'M', uplo, n, a, lda, rwork )
247 IF( anrm.GT.zero .AND. anrm.LT.rmin )
THEN
250 ELSE IF( anrm.GT.rmax )
THEN
255 $
CALL zlascl( uplo, 0, 0, one, sigma, n, n, a, lda, info )
262 llwork = lwork - indwrk + 1
263 CALL zhetrd( uplo, n, a, lda, w, rwork( inde ), work( indtau ),
264 $ work( indwrk ), llwork, iinfo )
269 IF( .NOT.wantz )
THEN
270 CALL dsterf( n, w, rwork( inde ), info )
272 CALL zungtr( uplo, n, a, lda, work( indtau ), work( indwrk ),
275 CALL zsteqr( jobz, n, w, rwork( inde ), a, lda,
276 $ rwork( indwrk ), info )
281 IF( iscale.EQ.1 )
THEN
287 CALL dscal( imax, one / sigma, w, 1 )
subroutine zungtr(UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
ZUNGTR
subroutine zlascl(TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO)
ZLASCL multiplies a general rectangular matrix by a real scalar defined as cto/cfrom.
subroutine zheev(JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, RWORK, INFO)
ZHEEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for HE matrices ...
subroutine dsterf(N, D, E, INFO)
DSTERF
subroutine zsteqr(COMPZ, N, D, E, Z, LDZ, WORK, INFO)
ZSTEQR
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dscal(N, DA, DX, INCX)
DSCAL
subroutine zhetrd(UPLO, N, A, LDA, D, E, TAU, WORK, LWORK, INFO)
ZHETRD