128 SUBROUTINE zhegs2( ITYPE, UPLO, N, A, LDA, B, LDB, INFO )
137 INTEGER INFO, ITYPE, LDA, LDB, N
140 COMPLEX*16 A( lda, * ), B( ldb, * )
146 DOUBLE PRECISION ONE, HALF
147 parameter ( one = 1.0d+0, half = 0.5d+0 )
149 parameter ( cone = ( 1.0d+0, 0.0d+0 ) )
154 DOUBLE PRECISION AKK, BKK
173 upper = lsame( uplo,
'U' )
174 IF( itype.LT.1 .OR. itype.GT.3 )
THEN
176 ELSE IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
178 ELSE IF( n.LT.0 )
THEN
180 ELSE IF( lda.LT.max( 1, n ) )
THEN
182 ELSE IF( ldb.LT.max( 1, n ) )
THEN
186 CALL xerbla(
'ZHEGS2', -info )
190 IF( itype.EQ.1 )
THEN
204 CALL zdscal( n-k, one / bkk, a( k, k+1 ), lda )
206 CALL zlacgv( n-k, a( k, k+1 ), lda )
207 CALL zlacgv( n-k, b( k, k+1 ), ldb )
208 CALL zaxpy( n-k, ct, b( k, k+1 ), ldb, a( k, k+1 ),
210 CALL zher2( uplo, n-k, -cone, a( k, k+1 ), lda,
211 $ b( k, k+1 ), ldb, a( k+1, k+1 ), lda )
212 CALL zaxpy( n-k, ct, b( k, k+1 ), ldb, a( k, k+1 ),
214 CALL zlacgv( n-k, b( k, k+1 ), ldb )
215 CALL ztrsv( uplo,
'Conjugate transpose',
'Non-unit',
216 $ n-k, b( k+1, k+1 ), ldb, a( k, k+1 ),
218 CALL zlacgv( n-k, a( k, k+1 ), lda )
234 CALL zdscal( n-k, one / bkk, a( k+1, k ), 1 )
236 CALL zaxpy( n-k, ct, b( k+1, k ), 1, a( k+1, k ), 1 )
237 CALL zher2( uplo, n-k, -cone, a( k+1, k ), 1,
238 $ b( k+1, k ), 1, a( k+1, k+1 ), lda )
239 CALL zaxpy( n-k, ct, b( k+1, k ), 1, a( k+1, k ), 1 )
240 CALL ztrsv( uplo,
'No transpose',
'Non-unit', n-k,
241 $ b( k+1, k+1 ), ldb, a( k+1, k ), 1 )
256 CALL ztrmv( uplo,
'No transpose',
'Non-unit', k-1, b,
257 $ ldb, a( 1, k ), 1 )
259 CALL zaxpy( k-1, ct, b( 1, k ), 1, a( 1, k ), 1 )
260 CALL zher2( uplo, k-1, cone, a( 1, k ), 1, b( 1, k ), 1,
262 CALL zaxpy( k-1, ct, b( 1, k ), 1, a( 1, k ), 1 )
263 CALL zdscal( k-1, bkk, a( 1, k ), 1 )
264 a( k, k ) = akk*bkk**2
276 CALL zlacgv( k-1, a( k, 1 ), lda )
277 CALL ztrmv( uplo,
'Conjugate transpose',
'Non-unit', k-1,
278 $ b, ldb, a( k, 1 ), lda )
280 CALL zlacgv( k-1, b( k, 1 ), ldb )
281 CALL zaxpy( k-1, ct, b( k, 1 ), ldb, a( k, 1 ), lda )
282 CALL zher2( uplo, k-1, cone, a( k, 1 ), lda, b( k, 1 ),
284 CALL zaxpy( k-1, ct, b( k, 1 ), ldb, a( k, 1 ), lda )
285 CALL zlacgv( k-1, b( k, 1 ), ldb )
286 CALL zdscal( k-1, bkk, a( k, 1 ), lda )
287 CALL zlacgv( k-1, a( k, 1 ), lda )
288 a( k, k ) = akk*bkk**2
subroutine ztrsv(UPLO, TRANS, DIAG, N, A, LDA, X, INCX)
ZTRSV
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine zher2(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
ZHER2
subroutine zhegs2(ITYPE, UPLO, N, A, LDA, B, LDB, INFO)
ZHEGS2 reduces a Hermitian definite generalized eigenproblem to standard form, using the factorizatio...
subroutine ztrmv(UPLO, TRANS, DIAG, N, A, LDA, X, INCX)
ZTRMV
subroutine zdscal(N, DA, ZX, INCX)
ZDSCAL
subroutine zaxpy(N, ZA, ZX, INCX, ZY, INCY)
ZAXPY
subroutine zlacgv(N, X, INCX)
ZLACGV conjugates a complex vector.