171 SUBROUTINE ssygv( ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W,
181 INTEGER INFO, ITYPE, LDA, LDB, LWORK, N
184 REAL A( LDA, * ), B( LDB, * ), W( * ), WORK( * )
191 PARAMETER ( ONE = 1.0e+0 )
194 LOGICAL LQUERY, UPPER, WANTZ
196 INTEGER LWKMIN, LWKOPT, NB, NEIG
202 EXTERNAL ilaenv, lsame, sroundup_lwork
215 wantz = lsame( jobz,
'V' )
216 upper = lsame( uplo,
'U' )
217 lquery = ( lwork.EQ.-1 )
220 IF( itype.LT.1 .OR. itype.GT.3 )
THEN
222 ELSE IF( .NOT.( wantz .OR. lsame( jobz,
'N' ) ) )
THEN
224 ELSE IF( .NOT.( upper .OR. lsame( uplo,
'L' ) ) )
THEN
226 ELSE IF( n.LT.0 )
THEN
228 ELSE IF( lda.LT.max( 1, n ) )
THEN
230 ELSE IF( ldb.LT.max( 1, n ) )
THEN
235 lwkmin = max( 1, 3*n - 1 )
236 nb = ilaenv( 1,
'SSYTRD', uplo, n, -1, -1, -1 )
237 lwkopt = max( lwkmin, ( nb + 2 )*n )
238 work( 1 ) = sroundup_lwork(lwkopt)
240 IF( lwork.LT.lwkmin .AND. .NOT.lquery )
THEN
246 CALL xerbla(
'SSYGV ', -info )
248 ELSE IF( lquery )
THEN
259 CALL spotrf( uplo, n, b, ldb, info )
267 CALL ssygst( itype, uplo, n, a, lda, b, ldb, info )
268 CALL ssyev( jobz, uplo, n, a, lda, w, work, lwork, info )
277 IF( itype.EQ.1 .OR. itype.EQ.2 )
THEN
288 CALL strsm(
'Left', uplo, trans,
'Non-unit', n, neig,
292 ELSE IF( itype.EQ.3 )
THEN
303 CALL strmm(
'Left', uplo, trans,
'Non-unit', n, neig,
309 work( 1 ) = sroundup_lwork(lwkopt)
subroutine ssyev(jobz, uplo, n, a, lda, w, work, lwork, info)
SSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices
subroutine ssygst(itype, uplo, n, a, lda, b, ldb, info)
SSYGST
subroutine ssygv(itype, jobz, uplo, n, a, lda, b, ldb, w, work, lwork, info)
SSYGV
subroutine strmm(side, uplo, transa, diag, m, n, alpha, a, lda, b, ldb)
STRMM
subroutine strsm(side, uplo, transa, diag, m, n, alpha, a, lda, b, ldb)
STRSM