183 SUBROUTINE ssytrf( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
192 INTEGER INFO, LDA, LWORK, N
196 REAL A( lda, * ), WORK( * )
202 LOGICAL LQUERY, UPPER
203 INTEGER IINFO, IWS, J, K, KB, LDWORK, LWKOPT, NB, NBMIN
208 EXTERNAL lsame, ilaenv
221 upper = lsame( uplo,
'U' )
222 lquery = ( lwork.EQ.-1 )
223 IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
225 ELSE IF( n.LT.0 )
THEN
227 ELSE IF( lda.LT.max( 1, n ) )
THEN
229 ELSE IF( lwork.LT.1 .AND. .NOT.lquery )
THEN
237 nb = ilaenv( 1,
'SSYTRF', uplo, n, -1, -1, -1 )
243 CALL xerbla(
'SSYTRF', -info )
245 ELSE IF( lquery )
THEN
251 IF( nb.GT.1 .AND. nb.LT.n )
THEN
253 IF( lwork.LT.iws )
THEN
254 nb = max( lwork / ldwork, 1 )
255 nbmin = max( 2, ilaenv( 2,
'SSYTRF', uplo, n, -1, -1, -1 ) )
284 CALL slasyf( uplo, k, nb, kb, a, lda, ipiv, work, ldwork,
290 CALL ssytf2( uplo, k, a, lda, ipiv, iinfo )
296 IF( info.EQ.0 .AND. iinfo.GT.0 )
325 CALL slasyf( uplo, n-k+1, nb, kb, a( k, k ), lda, ipiv( k ),
326 $ work, ldwork, iinfo )
331 CALL ssytf2( uplo, n-k+1, a( k, k ), lda, ipiv( k ), iinfo )
337 IF( info.EQ.0 .AND. iinfo.GT.0 )
338 $ info = iinfo + k - 1
342 DO 30 j = k, k + kb - 1
343 IF( ipiv( j ).GT.0 )
THEN
344 ipiv( j ) = ipiv( j ) + k - 1
346 ipiv( j ) = ipiv( j ) - k + 1
subroutine ssytrf(UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO)
SSYTRF
subroutine slasyf(UPLO, N, NB, KB, A, LDA, IPIV, W, LDW, INFO)
SLASYF computes a partial factorization of a real symmetric matrix using the Bunch-Kaufman diagonal p...
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine ssytf2(UPLO, N, A, LDA, IPIV, INFO)
SSYTF2 computes the factorization of a real symmetric indefinite matrix, using the diagonal pivoting ...