*> \brief \b ZSYTRF_AA_2STAGE * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download ZSYTRF_AA_2STAGE + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * SUBROUTINE ZSYTRF_AA_2STAGE( UPLO, N, A, LDA, TB, LTB, IPIV, * IPIV2, WORK, LWORK, INFO ) * * .. Scalar Arguments .. * CHARACTER UPLO * INTEGER N, LDA, LTB, LWORK, INFO * .. * .. Array Arguments .. * INTEGER IPIV( * ), IPIV2( * ) * COMPLEX*16 A( LDA, * ), TB( * ), WORK( * ) * .. * *> \par Purpose: * ============= *> *> \verbatim *> *> ZSYTRF_AA_2STAGE computes the factorization of a complex symmetric matrix A *> using the Aasen's algorithm. The form of the factorization is *> *> A = U**T*T*U or A = L*T*L**T *> *> where U (or L) is a product of permutation and unit upper (lower) *> triangular matrices, and T is a complex symmetric band matrix with the *> bandwidth of NB (NB is internally selected and stored in TB( 1 ), and T is *> LU factorized with partial pivoting). *> *> This is the blocked version of the algorithm, calling Level 3 BLAS. *> \endverbatim * * Arguments: * ========== * *> \param[in] UPLO *> \verbatim *> UPLO is CHARACTER*1 *> = 'U': Upper triangle of A is stored; *> = 'L': Lower triangle of A is stored. *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> The order of the matrix A. N >= 0. *> \endverbatim *> *> \param[in,out] A *> \verbatim *> A is COMPLEX*16 array, dimension (LDA,N) *> On entry, the hermitian matrix A. If UPLO = 'U', the leading *> N-by-N upper triangular part of A contains the upper *> triangular part of the matrix A, and the strictly lower *> triangular part of A is not referenced. If UPLO = 'L', the *> leading N-by-N lower triangular part of A contains the lower *> triangular part of the matrix A, and the strictly upper *> triangular part of A is not referenced. *> *> On exit, L is stored below (or above) the subdiaonal blocks, *> when UPLO is 'L' (or 'U'). *> \endverbatim *> *> \param[in] LDA *> \verbatim *> LDA is INTEGER *> The leading dimension of the array A. LDA >= max(1,N). *> \endverbatim *> *> \param[out] TB *> \verbatim *> TB is COMPLEX*16 array, dimension (LTB) *> On exit, details of the LU factorization of the band matrix. *> \endverbatim *> *> \param[in] LTB *> \verbatim *> LTB is INTEGER *> The size of the array TB. LTB >= 4*N, internally *> used to select NB such that LTB >= (3*NB+1)*N. *> *> If LTB = -1, then a workspace query is assumed; the *> routine only calculates the optimal size of LTB, *> returns this value as the first entry of TB, and *> no error message related to LTB is issued by XERBLA. *> \endverbatim *> *> \param[out] IPIV *> \verbatim *> IPIV is INTEGER array, dimension (N) *> On exit, it contains the details of the interchanges, i.e., *> the row and column k of A were interchanged with the *> row and column IPIV(k). *> \endverbatim *> *> \param[out] IPIV2 *> \verbatim *> IPIV2 is INTEGER array, dimension (N) *> On exit, it contains the details of the interchanges, i.e., *> the row and column k of T were interchanged with the *> row and column IPIV(k). *> \endverbatim *> *> \param[out] WORK *> \verbatim *> WORK is COMPLEX*16 workspace of size LWORK *> \endverbatim *> *> \param[in] LWORK *> \verbatim *> LWORK is INTEGER *> The size of WORK. LWORK >= N, internally used to select NB *> such that LWORK >= N*NB. *> *> If LWORK = -1, then a workspace query is assumed; the *> routine only calculates the optimal size of the WORK array, *> returns this value as the first entry of the WORK array, and *> no error message related to LWORK is issued by XERBLA. *> \endverbatim *> *> \param[out] INFO *> \verbatim *> INFO is INTEGER *> = 0: successful exit *> < 0: if INFO = -i, the i-th argument had an illegal value. *> > 0: if INFO = i, band LU factorization failed on i-th column *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup complex16SYcomputational * * ===================================================================== SUBROUTINE ZSYTRF_AA_2STAGE( UPLO, N, A, LDA, TB, LTB, IPIV, $ IPIV2, WORK, LWORK, INFO ) * * -- LAPACK computational routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * IMPLICIT NONE * * .. Scalar Arguments .. CHARACTER UPLO INTEGER N, LDA, LTB, LWORK, INFO * .. * .. Array Arguments .. INTEGER IPIV( * ), IPIV2( * ) COMPLEX*16 A( LDA, * ), TB( * ), WORK( * ) * .. * * ===================================================================== * .. Parameters .. COMPLEX*16 CZERO, CONE PARAMETER ( CZERO = ( 0.0D+0, 0.0D+0 ), $ CONE = ( 1.0D+0, 0.0D+0 ) ) * * .. Local Scalars .. LOGICAL UPPER, TQUERY, WQUERY INTEGER I, J, K, I1, I2, TD INTEGER LDTB, NB, KB, JB, NT, IINFO COMPLEX*16 PIV * .. * .. External Functions .. LOGICAL LSAME INTEGER ILAENV EXTERNAL LSAME, ILAENV * .. * .. External Subroutines .. EXTERNAL XERBLA, ZCOPY, ZGBTRF, ZGEMM, ZGETRF, $ ZLACPY, ZLASET, ZLASWP, ZTRSM, ZSWAP * .. * .. Intrinsic Functions .. INTRINSIC MIN, MAX * .. * .. Executable Statements .. * * Test the input parameters. * INFO = 0 UPPER = LSAME( UPLO, 'U' ) WQUERY = ( LWORK.EQ.-1 ) TQUERY = ( LTB.EQ.-1 ) IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN INFO = -1 ELSE IF( N.LT.0 ) THEN INFO = -2 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN INFO = -4 ELSE IF ( LTB .LT. 4*N .AND. .NOT.TQUERY ) THEN INFO = -6 ELSE IF ( LWORK .LT. N .AND. .NOT.WQUERY ) THEN INFO = -10 END IF * IF( INFO.NE.0 ) THEN CALL XERBLA( 'ZSYTRF_AA_2STAGE', -INFO ) RETURN END IF * * Answer the query * NB = ILAENV( 1, 'ZSYTRF_AA_2STAGE', UPLO, N, -1, -1, -1 ) IF( INFO.EQ.0 ) THEN IF( TQUERY ) THEN TB( 1 ) = (3*NB+1)*N END IF IF( WQUERY ) THEN WORK( 1 ) = N*NB END IF END IF IF( TQUERY .OR. WQUERY ) THEN RETURN END IF * * Quick return * IF ( N.EQ.0 ) THEN RETURN ENDIF * * Determine the number of the block size * LDTB = LTB/N IF( LDTB .LT. 3*NB+1 ) THEN NB = (LDTB-1)/3 END IF IF( LWORK .LT. NB*N ) THEN NB = LWORK/N END IF * * Determine the number of the block columns * NT = (N+NB-1)/NB TD = 2*NB KB = MIN(NB, N) * * Initialize vectors/matrices * DO J = 1, KB IPIV( J ) = J END DO * * Save NB * TB( 1 ) = NB * IF( UPPER ) THEN * * ..................................................... * Factorize A as U**T*D*U using the upper triangle of A * ..................................................... * DO J = 0, NT-1 * * Generate Jth column of W and H * KB = MIN(NB, N-J*NB) DO I = 1, J-1 IF( I.EQ.1 ) THEN * H(I,J) = T(I,I)*U(I,J) + T(I+1,I)*U(I+1,J) IF( I .EQ. (J-1) ) THEN JB = NB+KB ELSE JB = 2*NB END IF CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ NB, KB, JB, $ CONE, TB( TD+1 + (I*NB)*LDTB ), LDTB-1, $ A( (I-1)*NB+1, J*NB+1 ), LDA, $ CZERO, WORK( I*NB+1 ), N ) ELSE * H(I,J) = T(I,I-1)*U(I-1,J) + T(I,I)*U(I,J) + T(I,I+1)*U(I+1,J) IF( I .EQ. (J-1) ) THEN JB = 2*NB+KB ELSE JB = 3*NB END IF CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ NB, KB, JB, $ CONE, TB( TD+NB+1 + ((I-1)*NB)*LDTB ), $ LDTB-1, $ A( (I-2)*NB+1, J*NB+1 ), LDA, $ CZERO, WORK( I*NB+1 ), N ) END IF END DO * * Compute T(J,J) * CALL ZLACPY( 'Upper', KB, KB, A( J*NB+1, J*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) IF( J.GT.1 ) THEN * T(J,J) = U(1:J,J)'*H(1:J) CALL ZGEMM( 'Transpose', 'NoTranspose', $ KB, KB, (J-1)*NB, $ -CONE, A( 1, J*NB+1 ), LDA, $ WORK( NB+1 ), N, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) * T(J,J) += U(J,J)'*T(J,J-1)*U(J-1,J) CALL ZGEMM( 'Transpose', 'NoTranspose', $ KB, NB, KB, $ CONE, A( (J-1)*NB+1, J*NB+1 ), LDA, $ TB( TD+NB+1 + ((J-1)*NB)*LDTB ), LDTB-1, $ CZERO, WORK( 1 ), N ) CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ KB, KB, NB, $ -CONE, WORK( 1 ), N, $ A( (J-2)*NB+1, J*NB+1 ), LDA, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * * Expand T(J,J) into full format * DO I = 1, KB DO K = I+1, KB TB( TD+(K-I)+1 + (J*NB+I-1)*LDTB ) $ = TB( TD-(K-(I+1)) + (J*NB+K-1)*LDTB ) END DO END DO IF( J.GT.0 ) THEN c CALL CHEGST( 1, 'Upper', KB, c $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1, c $ A( (J-1)*NB+1, J*NB+1 ), LDA, IINFO ) CALL ZTRSM( 'L', 'U', 'T', 'N', KB, KB, CONE, $ A( (J-1)*NB+1, J*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) CALL ZTRSM( 'R', 'U', 'N', 'N', KB, KB, CONE, $ A( (J-1)*NB+1, J*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * IF( J.LT.NT-1 ) THEN IF( J.GT.0 ) THEN * * Compute H(J,J) * IF( J.EQ.1 ) THEN CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ KB, KB, KB, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1, $ A( (J-1)*NB+1, J*NB+1 ), LDA, $ CZERO, WORK( J*NB+1 ), N ) ELSE CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ KB, KB, NB+KB, $ CONE, TB( TD+NB+1 + ((J-1)*NB)*LDTB ), $ LDTB-1, $ A( (J-2)*NB+1, J*NB+1 ), LDA, $ CZERO, WORK( J*NB+1 ), N ) END IF * * Update with the previous column * CALL ZGEMM( 'Transpose', 'NoTranspose', $ NB, N-(J+1)*NB, J*NB, $ -CONE, WORK( NB+1 ), N, $ A( 1, (J+1)*NB+1 ), LDA, $ CONE, A( J*NB+1, (J+1)*NB+1 ), LDA ) END IF * * Copy panel to workspace to call ZGETRF * DO K = 1, NB CALL ZCOPY( N-(J+1)*NB, $ A( J*NB+K, (J+1)*NB+1 ), LDA, $ WORK( 1+(K-1)*N ), 1 ) END DO * * Factorize panel * CALL ZGETRF( N-(J+1)*NB, NB, $ WORK, N, $ IPIV( (J+1)*NB+1 ), IINFO ) c IF (IINFO.NE.0 .AND. INFO.EQ.0) THEN c INFO = IINFO+(J+1)*NB c END IF * * Copy panel back * DO K = 1, NB CALL ZCOPY( N-(J+1)*NB, $ WORK( 1+(K-1)*N ), 1, $ A( J*NB+K, (J+1)*NB+1 ), LDA ) END DO * * Compute T(J+1, J), zero out for GEMM update * KB = MIN(NB, N-(J+1)*NB) CALL ZLASET( 'Full', KB, NB, CZERO, CZERO, $ TB( TD+NB+1 + (J*NB)*LDTB), LDTB-1 ) CALL ZLACPY( 'Upper', KB, NB, $ WORK, N, $ TB( TD+NB+1 + (J*NB)*LDTB ), LDTB-1 ) IF( J.GT.0 ) THEN CALL ZTRSM( 'R', 'U', 'N', 'U', KB, NB, CONE, $ A( (J-1)*NB+1, J*NB+1 ), LDA, $ TB( TD+NB+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * * Copy T(J,J+1) into T(J+1, J), both upper/lower for GEMM * updates * DO K = 1, NB DO I = 1, KB TB( TD-NB+K-I+1 + (J*NB+NB+I-1)*LDTB ) $ = TB( TD+NB+I-K+1 + (J*NB+K-1)*LDTB ) END DO END DO CALL ZLASET( 'Lower', KB, NB, CZERO, CONE, $ A( J*NB+1, (J+1)*NB+1), LDA ) * * Apply pivots to trailing submatrix of A * DO K = 1, KB * > Adjust ipiv IPIV( (J+1)*NB+K ) = IPIV( (J+1)*NB+K ) + (J+1)*NB * I1 = (J+1)*NB+K I2 = IPIV( (J+1)*NB+K ) IF( I1.NE.I2 ) THEN * > Apply pivots to previous columns of L CALL ZSWAP( K-1, A( (J+1)*NB+1, I1 ), 1, $ A( (J+1)*NB+1, I2 ), 1 ) * > Swap A(I1+1:M, I1) with A(I2, I1+1:M) IF( I2.GT.(I1+1) ) $ CALL ZSWAP( I2-I1-1, A( I1, I1+1 ), LDA, $ A( I1+1, I2 ), 1 ) * > Swap A(I2+1:M, I1) with A(I2+1:M, I2) IF( I2.LT.N ) $ CALL ZSWAP( N-I2, A( I1, I2+1 ), LDA, $ A( I2, I2+1 ), LDA ) * > Swap A(I1, I1) with A(I2, I2) PIV = A( I1, I1 ) A( I1, I1 ) = A( I2, I2 ) A( I2, I2 ) = PIV * > Apply pivots to previous columns of L IF( J.GT.0 ) THEN CALL ZSWAP( J*NB, A( 1, I1 ), 1, $ A( 1, I2 ), 1 ) END IF ENDIF END DO END IF END DO ELSE * * ..................................................... * Factorize A as L*D*L**T using the lower triangle of A * ..................................................... * DO J = 0, NT-1 * * Generate Jth column of W and H * KB = MIN(NB, N-J*NB) DO I = 1, J-1 IF( I.EQ.1 ) THEN * H(I,J) = T(I,I)*L(J,I)' + T(I+1,I)'*L(J,I+1)' IF( I .EQ. (J-1) ) THEN JB = NB+KB ELSE JB = 2*NB END IF CALL ZGEMM( 'NoTranspose', 'Transpose', $ NB, KB, JB, $ CONE, TB( TD+1 + (I*NB)*LDTB ), LDTB-1, $ A( J*NB+1, (I-1)*NB+1 ), LDA, $ CZERO, WORK( I*NB+1 ), N ) ELSE * H(I,J) = T(I,I-1)*L(J,I-1)' + T(I,I)*L(J,I)' + T(I,I+1)*L(J,I+1)' IF( I .EQ. (J-1) ) THEN JB = 2*NB+KB ELSE JB = 3*NB END IF CALL ZGEMM( 'NoTranspose', 'Transpose', $ NB, KB, JB, $ CONE, TB( TD+NB+1 + ((I-1)*NB)*LDTB ), $ LDTB-1, $ A( J*NB+1, (I-2)*NB+1 ), LDA, $ CZERO, WORK( I*NB+1 ), N ) END IF END DO * * Compute T(J,J) * CALL ZLACPY( 'Lower', KB, KB, A( J*NB+1, J*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) IF( J.GT.1 ) THEN * T(J,J) = L(J,1:J)*H(1:J) CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ KB, KB, (J-1)*NB, $ -CONE, A( J*NB+1, 1 ), LDA, $ WORK( NB+1 ), N, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) * T(J,J) += L(J,J)*T(J,J-1)*L(J,J-1)' CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ KB, NB, KB, $ CONE, A( J*NB+1, (J-1)*NB+1 ), LDA, $ TB( TD+NB+1 + ((J-1)*NB)*LDTB ), LDTB-1, $ CZERO, WORK( 1 ), N ) CALL ZGEMM( 'NoTranspose', 'Transpose', $ KB, KB, NB, $ -CONE, WORK( 1 ), N, $ A( J*NB+1, (J-2)*NB+1 ), LDA, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * * Expand T(J,J) into full format * DO I = 1, KB DO K = I+1, KB TB( TD-(K-(I+1)) + (J*NB+K-1)*LDTB ) $ = TB( TD+(K-I)+1 + (J*NB+I-1)*LDTB ) END DO END DO IF( J.GT.0 ) THEN c CALL CHEGST( 1, 'Lower', KB, c $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1, c $ A( J*NB+1, (J-1)*NB+1 ), LDA, IINFO ) CALL ZTRSM( 'L', 'L', 'N', 'N', KB, KB, CONE, $ A( J*NB+1, (J-1)*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) CALL ZTRSM( 'R', 'L', 'T', 'N', KB, KB, CONE, $ A( J*NB+1, (J-1)*NB+1 ), LDA, $ TB( TD+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * * Symmetrize T(J,J) * DO I = 1, KB DO K = I+1, KB TB( TD-(K-(I+1)) + (J*NB+K-1)*LDTB ) $ = TB( TD+(K-I)+1 + (J*NB+I-1)*LDTB ) END DO END DO * IF( J.LT.NT-1 ) THEN IF( J.GT.0 ) THEN * * Compute H(J,J) * IF( J.EQ.1 ) THEN CALL ZGEMM( 'NoTranspose', 'Transpose', $ KB, KB, KB, $ CONE, TB( TD+1 + (J*NB)*LDTB ), LDTB-1, $ A( J*NB+1, (J-1)*NB+1 ), LDA, $ CZERO, WORK( J*NB+1 ), N ) ELSE CALL ZGEMM( 'NoTranspose', 'Transpose', $ KB, KB, NB+KB, $ CONE, TB( TD+NB+1 + ((J-1)*NB)*LDTB ), $ LDTB-1, $ A( J*NB+1, (J-2)*NB+1 ), LDA, $ CZERO, WORK( J*NB+1 ), N ) END IF * * Update with the previous column * CALL ZGEMM( 'NoTranspose', 'NoTranspose', $ N-(J+1)*NB, NB, J*NB, $ -CONE, A( (J+1)*NB+1, 1 ), LDA, $ WORK( NB+1 ), N, $ CONE, A( (J+1)*NB+1, J*NB+1 ), LDA ) END IF * * Factorize panel * CALL ZGETRF( N-(J+1)*NB, NB, $ A( (J+1)*NB+1, J*NB+1 ), LDA, $ IPIV( (J+1)*NB+1 ), IINFO ) c IF (IINFO.NE.0 .AND. INFO.EQ.0) THEN c INFO = IINFO+(J+1)*NB c END IF * * Compute T(J+1, J), zero out for GEMM update * KB = MIN(NB, N-(J+1)*NB) CALL ZLASET( 'Full', KB, NB, CZERO, CZERO, $ TB( TD+NB+1 + (J*NB)*LDTB), LDTB-1 ) CALL ZLACPY( 'Upper', KB, NB, $ A( (J+1)*NB+1, J*NB+1 ), LDA, $ TB( TD+NB+1 + (J*NB)*LDTB ), LDTB-1 ) IF( J.GT.0 ) THEN CALL ZTRSM( 'R', 'L', 'T', 'U', KB, NB, CONE, $ A( J*NB+1, (J-1)*NB+1 ), LDA, $ TB( TD+NB+1 + (J*NB)*LDTB ), LDTB-1 ) END IF * * Copy T(J+1,J) into T(J, J+1), both upper/lower for GEMM * updates * DO K = 1, NB DO I = 1, KB TB( TD-NB+K-I+1 + (J*NB+NB+I-1)*LDTB ) = $ TB( TD+NB+I-K+1 + (J*NB+K-1)*LDTB ) END DO END DO CALL ZLASET( 'Upper', KB, NB, CZERO, CONE, $ A( (J+1)*NB+1, J*NB+1 ), LDA ) * * Apply pivots to trailing submatrix of A * DO K = 1, KB * > Adjust ipiv IPIV( (J+1)*NB+K ) = IPIV( (J+1)*NB+K ) + (J+1)*NB * I1 = (J+1)*NB+K I2 = IPIV( (J+1)*NB+K ) IF( I1.NE.I2 ) THEN * > Apply pivots to previous columns of L CALL ZSWAP( K-1, A( I1, (J+1)*NB+1 ), LDA, $ A( I2, (J+1)*NB+1 ), LDA ) * > Swap A(I1+1:M, I1) with A(I2, I1+1:M) IF( I2.GT.(I1+1) ) $ CALL ZSWAP( I2-I1-1, A( I1+1, I1 ), 1, $ A( I2, I1+1 ), LDA ) * > Swap A(I2+1:M, I1) with A(I2+1:M, I2) IF( I2.LT.N ) $ CALL ZSWAP( N-I2, A( I2+1, I1 ), 1, $ A( I2+1, I2 ), 1 ) * > Swap A(I1, I1) with A(I2, I2) PIV = A( I1, I1 ) A( I1, I1 ) = A( I2, I2 ) A( I2, I2 ) = PIV * > Apply pivots to previous columns of L IF( J.GT.0 ) THEN CALL ZSWAP( J*NB, A( I1, 1 ), LDA, $ A( I2, 1 ), LDA ) END IF ENDIF END DO * * Apply pivots to previous columns of L * c CALL ZLASWP( J*NB, A( 1, 1 ), LDA, c $ (J+1)*NB+1, (J+1)*NB+KB, IPIV, 1 ) END IF END DO END IF * * Factor the band matrix CALL ZGBTRF( N, N, NB, NB, TB, LDTB, IPIV2, INFO ) * RETURN * * End of ZSYTRF_AA_2STAGE * END