*> \brief \b DISNAN tests input for NaN. * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download DISNAN + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * LOGICAL FUNCTION DISNAN( DIN ) * * .. Scalar Arguments .. * DOUBLE PRECISION, INTENT(IN) :: DIN * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DISNAN returns .TRUE. if its argument is NaN, and .FALSE. *> otherwise. To be replaced by the Fortran 2003 intrinsic in the *> future. *> \endverbatim * * Arguments: * ========== * *> \param[in] DIN *> \verbatim *> DIN is DOUBLE PRECISION *> Input to test for NaN. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup isnan * * ===================================================================== LOGICAL FUNCTION DISNAN( DIN ) * * -- LAPACK auxiliary routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. DOUBLE PRECISION, INTENT(IN) :: DIN * .. * * ===================================================================== * * .. External Functions .. LOGICAL DLAISNAN EXTERNAL DLAISNAN * .. * .. Executable Statements .. DISNAN = DLAISNAN(DIN,DIN) RETURN END *> \brief \b DLAISNAN tests input for NaN by comparing two arguments for inequality. * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download DLAISNAN + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 ) * * .. Scalar Arguments .. * DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2 * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> This routine is not for general use. It exists solely to avoid *> over-optimization in DISNAN. *> *> DLAISNAN checks for NaNs by comparing its two arguments for *> inequality. NaN is the only floating-point value where NaN != NaN *> returns .TRUE. To check for NaNs, pass the same variable as both *> arguments. *> *> A compiler must assume that the two arguments are *> not the same variable, and the test will not be optimized away. *> Interprocedural or whole-program optimization may delete this *> test. The ISNAN functions will be replaced by the correct *> Fortran 03 intrinsic once the intrinsic is widely available. *> \endverbatim * * Arguments: * ========== * *> \param[in] DIN1 *> \verbatim *> DIN1 is DOUBLE PRECISION *> \endverbatim *> *> \param[in] DIN2 *> \verbatim *> DIN2 is DOUBLE PRECISION *> Two numbers to compare for inequality. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup laisnan * * ===================================================================== LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 ) * * -- LAPACK auxiliary routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2 * .. * * ===================================================================== * * .. Executable Statements .. DLAISNAN = (DIN1.NE.DIN2) RETURN END *> \brief \b DSCAL * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE DSCAL(N,DA,DX,INCX) * * .. Scalar Arguments .. * DOUBLE PRECISION DA * INTEGER INCX,N * .. * .. Array Arguments .. * DOUBLE PRECISION DX(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DSCAL scales a vector by a constant. *> uses unrolled loops for increment equal to 1. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in] DA *> \verbatim *> DA is DOUBLE PRECISION *> On entry, DA specifies the scalar alpha. *> \endverbatim *> *> \param[in,out] DX *> \verbatim *> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of DX *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup scal * *> \par Further Details: * ===================== *> *> \verbatim *> *> jack dongarra, linpack, 3/11/78. *> modified 3/93 to return if incx .le. 0. *> modified 12/3/93, array(1) declarations changed to array(*) *> \endverbatim *> * ===================================================================== SUBROUTINE DSCAL(N,DA,DX,INCX) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. DOUBLE PRECISION DA INTEGER INCX,N * .. * .. Array Arguments .. DOUBLE PRECISION DX(*) * .. * * ===================================================================== * * .. Local Scalars .. INTEGER I,M,MP1,NINCX * .. Parameters .. DOUBLE PRECISION ONE PARAMETER (ONE=1.0D+0) * .. * .. Intrinsic Functions .. INTRINSIC MOD * .. IF (N.LE.0 .OR. INCX.LE.0 .OR. DA.EQ.ONE) RETURN IF (INCX.EQ.1) THEN * * code for increment equal to 1 * * * clean-up loop * M = MOD(N,5) IF (M.NE.0) THEN DO I = 1,M DX(I) = DA*DX(I) END DO IF (N.LT.5) RETURN END IF MP1 = M + 1 DO I = MP1,N,5 DX(I) = DA*DX(I) DX(I+1) = DA*DX(I+1) DX(I+2) = DA*DX(I+2) DX(I+3) = DA*DX(I+3) DX(I+4) = DA*DX(I+4) END DO ELSE * * code for increment not equal to 1 * NINCX = N*INCX DO I = 1,NINCX,INCX DX(I) = DA*DX(I) END DO END IF RETURN * * End of DSCAL * END *> \brief \b DSWAP * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) * * .. Scalar Arguments .. * INTEGER INCX,INCY,N * .. * .. Array Arguments .. * DOUBLE PRECISION DX(*),DY(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DSWAP interchanges two vectors. *> uses unrolled loops for increments equal to 1. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in,out] DX *> \verbatim *> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of DX *> \endverbatim *> *> \param[in,out] DY *> \verbatim *> DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) ) *> \endverbatim *> *> \param[in] INCY *> \verbatim *> INCY is INTEGER *> storage spacing between elements of DY *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup swap * *> \par Further Details: * ===================== *> *> \verbatim *> *> jack dongarra, linpack, 3/11/78. *> modified 12/3/93, array(1) declarations changed to array(*) *> \endverbatim *> * ===================================================================== SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX,INCY,N * .. * .. Array Arguments .. DOUBLE PRECISION DX(*),DY(*) * .. * * ===================================================================== * * .. Local Scalars .. DOUBLE PRECISION DTEMP INTEGER I,IX,IY,M,MP1 * .. * .. Intrinsic Functions .. INTRINSIC MOD * .. IF (N.LE.0) RETURN IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN * * code for both increments equal to 1 * * * clean-up loop * M = MOD(N,3) IF (M.NE.0) THEN DO I = 1,M DTEMP = DX(I) DX(I) = DY(I) DY(I) = DTEMP END DO IF (N.LT.3) RETURN END IF MP1 = M + 1 DO I = MP1,N,3 DTEMP = DX(I) DX(I) = DY(I) DY(I) = DTEMP DTEMP = DX(I+1) DX(I+1) = DY(I+1) DY(I+1) = DTEMP DTEMP = DX(I+2) DX(I+2) = DY(I+2) DY(I+2) = DTEMP END DO ELSE * * code for unequal increments or equal increments not equal * to 1 * IX = 1 IY = 1 IF (INCX.LT.0) IX = (-N+1)*INCX + 1 IF (INCY.LT.0) IY = (-N+1)*INCY + 1 DO I = 1,N DTEMP = DX(IX) DX(IX) = DY(IY) DY(IY) = DTEMP IX = IX + INCX IY = IY + INCY END DO END IF RETURN * * End of DSWAP * END *> \brief \b DSYR * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE DSYR(UPLO,N,ALPHA,X,INCX,A,LDA) * * .. Scalar Arguments .. * DOUBLE PRECISION ALPHA * INTEGER INCX,LDA,N * CHARACTER UPLO * .. * .. Array Arguments .. * DOUBLE PRECISION A(LDA,*),X(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DSYR performs the symmetric rank 1 operation *> *> A := alpha*x*x**T + A, *> *> where alpha is a real scalar, x is an n element vector and A is an *> n by n symmetric matrix. *> \endverbatim * * Arguments: * ========== * *> \param[in] UPLO *> \verbatim *> UPLO is CHARACTER*1 *> On entry, UPLO specifies whether the upper or lower *> triangular part of the array A is to be referenced as *> follows: *> *> UPLO = 'U' or 'u' Only the upper triangular part of A *> is to be referenced. *> *> UPLO = 'L' or 'l' Only the lower triangular part of A *> is to be referenced. *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> On entry, N specifies the order of the matrix A. *> N must be at least zero. *> \endverbatim *> *> \param[in] ALPHA *> \verbatim *> ALPHA is DOUBLE PRECISION. *> On entry, ALPHA specifies the scalar alpha. *> \endverbatim *> *> \param[in] X *> \verbatim *> X is DOUBLE PRECISION array, dimension at least *> ( 1 + ( n - 1 )*abs( INCX ) ). *> Before entry, the incremented array X must contain the n *> element vector x. *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> On entry, INCX specifies the increment for the elements of *> X. INCX must not be zero. *> \endverbatim *> *> \param[in,out] A *> \verbatim *> A is DOUBLE PRECISION array, dimension ( LDA, N ) *> Before entry with UPLO = 'U' or 'u', the leading n by n *> upper triangular part of the array A must contain the upper *> triangular part of the symmetric matrix and the strictly *> lower triangular part of A is not referenced. On exit, the *> upper triangular part of the array A is overwritten by the *> upper triangular part of the updated matrix. *> Before entry with UPLO = 'L' or 'l', the leading n by n *> lower triangular part of the array A must contain the lower *> triangular part of the symmetric matrix and the strictly *> upper triangular part of A is not referenced. On exit, the *> lower triangular part of the array A is overwritten by the *> lower triangular part of the updated matrix. *> \endverbatim *> *> \param[in] LDA *> \verbatim *> LDA is INTEGER *> On entry, LDA specifies the first dimension of A as declared *> in the calling (sub) program. LDA must be at least *> max( 1, n ). *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup her * *> \par Further Details: * ===================== *> *> \verbatim *> *> Level 2 Blas routine. *> *> -- Written on 22-October-1986. *> Jack Dongarra, Argonne National Lab. *> Jeremy Du Croz, Nag Central Office. *> Sven Hammarling, Nag Central Office. *> Richard Hanson, Sandia National Labs. *> \endverbatim *> * ===================================================================== SUBROUTINE DSYR(UPLO,N,ALPHA,X,INCX,A,LDA) * * -- Reference BLAS level2 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. DOUBLE PRECISION ALPHA INTEGER INCX,LDA,N CHARACTER UPLO * .. * .. Array Arguments .. DOUBLE PRECISION A(LDA,*),X(*) * .. * * ===================================================================== * * .. Parameters .. DOUBLE PRECISION ZERO PARAMETER (ZERO=0.0D+0) * .. * .. Local Scalars .. DOUBLE PRECISION TEMP INTEGER I,INFO,IX,J,JX,KX * .. * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. * .. External Subroutines .. EXTERNAL XERBLA * .. * .. Intrinsic Functions .. INTRINSIC MAX * .. * * Test the input parameters. * INFO = 0 IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN INFO = 1 ELSE IF (N.LT.0) THEN INFO = 2 ELSE IF (INCX.EQ.0) THEN INFO = 5 ELSE IF (LDA.LT.MAX(1,N)) THEN INFO = 7 END IF IF (INFO.NE.0) THEN CALL XERBLA('DSYR ',INFO) RETURN END IF * * Quick return if possible. * IF ((N.EQ.0) .OR. (ALPHA.EQ.ZERO)) RETURN * * Set the start point in X if the increment is not unity. * IF (INCX.LE.0) THEN KX = 1 - (N-1)*INCX ELSE IF (INCX.NE.1) THEN KX = 1 END IF * * Start the operations. In this version the elements of A are * accessed sequentially with one pass through the triangular part * of A. * IF (LSAME(UPLO,'U')) THEN * * Form A when A is stored in upper triangle. * IF (INCX.EQ.1) THEN DO 20 J = 1,N IF (X(J).NE.ZERO) THEN TEMP = ALPHA*X(J) DO 10 I = 1,J A(I,J) = A(I,J) + X(I)*TEMP 10 CONTINUE END IF 20 CONTINUE ELSE JX = KX DO 40 J = 1,N IF (X(JX).NE.ZERO) THEN TEMP = ALPHA*X(JX) IX = KX DO 30 I = 1,J A(I,J) = A(I,J) + X(IX)*TEMP IX = IX + INCX 30 CONTINUE END IF JX = JX + INCX 40 CONTINUE END IF ELSE * * Form A when A is stored in lower triangle. * IF (INCX.EQ.1) THEN DO 60 J = 1,N IF (X(J).NE.ZERO) THEN TEMP = ALPHA*X(J) DO 50 I = J,N A(I,J) = A(I,J) + X(I)*TEMP 50 CONTINUE END IF 60 CONTINUE ELSE JX = KX DO 80 J = 1,N IF (X(JX).NE.ZERO) THEN TEMP = ALPHA*X(JX) IX = JX DO 70 I = J,N A(I,J) = A(I,J) + X(IX)*TEMP IX = IX + INCX 70 CONTINUE END IF JX = JX + INCX 80 CONTINUE END IF END IF * RETURN * * End of DSYR * END *> \brief \b DSYTF2 computes the factorization of a real symmetric indefinite matrix, using the diagonal pivoting method (unblocked algorithm). * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download DSYTF2 + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * SUBROUTINE DSYTF2( UPLO, N, A, LDA, IPIV, INFO ) * * .. Scalar Arguments .. * CHARACTER UPLO * INTEGER INFO, LDA, N * .. * .. Array Arguments .. * INTEGER IPIV( * ) * DOUBLE PRECISION A( LDA, * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DSYTF2 computes the factorization of a real symmetric matrix A using *> the Bunch-Kaufman diagonal pivoting method: *> *> A = U*D*U**T or A = L*D*L**T *> *> where U (or L) is a product of permutation and unit upper (lower) *> triangular matrices, U**T is the transpose of U, and D is symmetric and *> block diagonal with 1-by-1 and 2-by-2 diagonal blocks. *> *> This is the unblocked version of the algorithm, calling Level 2 BLAS. *> \endverbatim * * Arguments: * ========== * *> \param[in] UPLO *> \verbatim *> UPLO is CHARACTER*1 *> Specifies whether the upper or lower triangular part of the *> symmetric matrix A is stored: *> = 'U': Upper triangular *> = 'L': Lower triangular *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> The order of the matrix A. N >= 0. *> \endverbatim *> *> \param[in,out] A *> \verbatim *> A is DOUBLE PRECISION array, dimension (LDA,N) *> On entry, the symmetric 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, the block diagonal matrix D and the multipliers used *> to obtain the factor U or L (see below for further details). *> \endverbatim *> *> \param[in] LDA *> \verbatim *> LDA is INTEGER *> The leading dimension of the array A. LDA >= max(1,N). *> \endverbatim *> *> \param[out] IPIV *> \verbatim *> IPIV is INTEGER array, dimension (N) *> Details of the interchanges and the block structure of D. *> *> If UPLO = 'U': *> If IPIV(k) > 0, then rows and columns k and IPIV(k) were *> interchanged and D(k,k) is a 1-by-1 diagonal block. *> *> If IPIV(k) = IPIV(k-1) < 0, then rows and columns *> k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k) *> is a 2-by-2 diagonal block. *> *> If UPLO = 'L': *> If IPIV(k) > 0, then rows and columns k and IPIV(k) were *> interchanged and D(k,k) is a 1-by-1 diagonal block. *> *> If IPIV(k) = IPIV(k+1) < 0, then rows and columns *> k+1 and -IPIV(k) were interchanged and D(k:k+1,k:k+1) *> is a 2-by-2 diagonal block. *> \endverbatim *> *> \param[out] INFO *> \verbatim *> INFO is INTEGER *> = 0: successful exit *> < 0: if INFO = -k, the k-th argument had an illegal value *> > 0: if INFO = k, D(k,k) is exactly zero. The factorization *> has been completed, but the block diagonal matrix D is *> exactly singular, and division by zero will occur if it *> is used to solve a system of equations. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup hetf2 * *> \par Further Details: * ===================== *> *> \verbatim *> *> If UPLO = 'U', then A = U*D*U**T, where *> U = P(n)*U(n)* ... *P(k)U(k)* ..., *> i.e., U is a product of terms P(k)*U(k), where k decreases from n to *> 1 in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1 *> and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as *> defined by IPIV(k), and U(k) is a unit upper triangular matrix, such *> that if the diagonal block D(k) is of order s (s = 1 or 2), then *> *> ( I v 0 ) k-s *> U(k) = ( 0 I 0 ) s *> ( 0 0 I ) n-k *> k-s s n-k *> *> If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k). *> If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k), *> and A(k,k), and v overwrites A(1:k-2,k-1:k). *> *> If UPLO = 'L', then A = L*D*L**T, where *> L = P(1)*L(1)* ... *P(k)*L(k)* ..., *> i.e., L is a product of terms P(k)*L(k), where k increases from 1 to *> n in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1 *> and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as *> defined by IPIV(k), and L(k) is a unit lower triangular matrix, such *> that if the diagonal block D(k) is of order s (s = 1 or 2), then *> *> ( I 0 0 ) k-1 *> L(k) = ( 0 I 0 ) s *> ( 0 v I ) n-k-s+1 *> k-1 s n-k-s+1 *> *> If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k). *> If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k), *> and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1). *> \endverbatim * *> \par Contributors: * ================== *> *> \verbatim *> *> 09-29-06 - patch from *> Bobby Cheng, MathWorks *> *> Replace l.204 and l.372 *> IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN *> by *> IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. DISNAN(ABSAKK) ) THEN *> *> 01-01-96 - Based on modifications by *> J. Lewis, Boeing Computer Services Company *> A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA *> 1-96 - Based on modifications by J. Lewis, Boeing Computer Services *> Company *> \endverbatim * * ===================================================================== SUBROUTINE DSYTF2( UPLO, N, A, LDA, IPIV, 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..-- * * .. Scalar Arguments .. CHARACTER UPLO INTEGER INFO, LDA, N * .. * .. Array Arguments .. INTEGER IPIV( * ) DOUBLE PRECISION A( LDA, * ) * .. * * ===================================================================== * * .. Parameters .. DOUBLE PRECISION ZERO, ONE PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 ) DOUBLE PRECISION EIGHT, SEVTEN PARAMETER ( EIGHT = 8.0D+0, SEVTEN = 17.0D+0 ) * .. * .. Local Scalars .. LOGICAL UPPER INTEGER I, IMAX, J, JMAX, K, KK, KP, KSTEP DOUBLE PRECISION ABSAKK, ALPHA, COLMAX, D11, D12, D21, D22, R1, $ ROWMAX, T, WK, WKM1, WKP1 * .. * .. External Functions .. LOGICAL LSAME, DISNAN INTEGER IDAMAX EXTERNAL LSAME, IDAMAX, DISNAN * .. * .. External Subroutines .. EXTERNAL DSCAL, DSWAP, DSYR, XERBLA * .. * .. Intrinsic Functions .. INTRINSIC ABS, MAX, SQRT * .. * .. Executable Statements .. * * Test the input parameters. * INFO = 0 UPPER = LSAME( UPLO, 'U' ) 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 END IF IF( INFO.NE.0 ) THEN CALL XERBLA( 'DSYTF2', -INFO ) RETURN END IF * * Initialize ALPHA for use in choosing pivot block size. * ALPHA = ( ONE+SQRT( SEVTEN ) ) / EIGHT * IF( UPPER ) THEN * * Factorize A as U*D*U**T using the upper triangle of A * * K is the main loop index, decreasing from N to 1 in steps of * 1 or 2 * K = N 10 CONTINUE * * If K < 1, exit from loop * IF( K.LT.1 ) $ GO TO 70 KSTEP = 1 * * Determine rows and columns to be interchanged and whether * a 1-by-1 or 2-by-2 pivot block will be used * ABSAKK = ABS( A( K, K ) ) * * IMAX is the row-index of the largest off-diagonal element in * column K, and COLMAX is its absolute value. * Determine both COLMAX and IMAX. * IF( K.GT.1 ) THEN IMAX = IDAMAX( K-1, A( 1, K ), 1 ) COLMAX = ABS( A( IMAX, K ) ) ELSE COLMAX = ZERO END IF * IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. $ DISNAN(ABSAKK) ) THEN * * Column K is zero or underflow, or contains a NaN: * set INFO and continue * IF( INFO.EQ.0 ) $ INFO = K KP = K ELSE IF( ABSAKK.GE.ALPHA*COLMAX ) THEN * * no interchange, use 1-by-1 pivot block * KP = K ELSE * * JMAX is the column-index of the largest off-diagonal * element in row IMAX, and ROWMAX is its absolute value * JMAX = IMAX + IDAMAX( K-IMAX, A( IMAX, IMAX+1 ), LDA ) ROWMAX = ABS( A( IMAX, JMAX ) ) IF( IMAX.GT.1 ) THEN JMAX = IDAMAX( IMAX-1, A( 1, IMAX ), 1 ) ROWMAX = MAX( ROWMAX, ABS( A( JMAX, IMAX ) ) ) END IF * IF( ABSAKK.GE.ALPHA*COLMAX*( COLMAX / ROWMAX ) ) THEN * * no interchange, use 1-by-1 pivot block * KP = K ELSE IF( ABS( A( IMAX, IMAX ) ).GE.ALPHA*ROWMAX ) THEN * * interchange rows and columns K and IMAX, use 1-by-1 * pivot block * KP = IMAX ELSE * * interchange rows and columns K-1 and IMAX, use 2-by-2 * pivot block * KP = IMAX KSTEP = 2 END IF END IF * KK = K - KSTEP + 1 IF( KP.NE.KK ) THEN * * Interchange rows and columns KK and KP in the leading * submatrix A(1:k,1:k) * CALL DSWAP( KP-1, A( 1, KK ), 1, A( 1, KP ), 1 ) CALL DSWAP( KK-KP-1, A( KP+1, KK ), 1, A( KP, KP+1 ), $ LDA ) T = A( KK, KK ) A( KK, KK ) = A( KP, KP ) A( KP, KP ) = T IF( KSTEP.EQ.2 ) THEN T = A( K-1, K ) A( K-1, K ) = A( KP, K ) A( KP, K ) = T END IF END IF * * Update the leading submatrix * IF( KSTEP.EQ.1 ) THEN * * 1-by-1 pivot block D(k): column k now holds * * W(k) = U(k)*D(k) * * where U(k) is the k-th column of U * * Perform a rank-1 update of A(1:k-1,1:k-1) as * * A := A - U(k)*D(k)*U(k)**T = A - W(k)*1/D(k)*W(k)**T * R1 = ONE / A( K, K ) CALL DSYR( UPLO, K-1, -R1, A( 1, K ), 1, A, LDA ) * * Store U(k) in column k * CALL DSCAL( K-1, R1, A( 1, K ), 1 ) ELSE * * 2-by-2 pivot block D(k): columns k and k-1 now hold * * ( W(k-1) W(k) ) = ( U(k-1) U(k) )*D(k) * * where U(k) and U(k-1) are the k-th and (k-1)-th columns * of U * * Perform a rank-2 update of A(1:k-2,1:k-2) as * * A := A - ( U(k-1) U(k) )*D(k)*( U(k-1) U(k) )**T * = A - ( W(k-1) W(k) )*inv(D(k))*( W(k-1) W(k) )**T * IF( K.GT.2 ) THEN * D12 = A( K-1, K ) D22 = A( K-1, K-1 ) / D12 D11 = A( K, K ) / D12 T = ONE / ( D11*D22-ONE ) D12 = T / D12 * DO 30 J = K - 2, 1, -1 WKM1 = D12*( D11*A( J, K-1 )-A( J, K ) ) WK = D12*( D22*A( J, K )-A( J, K-1 ) ) DO 20 I = J, 1, -1 A( I, J ) = A( I, J ) - A( I, K )*WK - $ A( I, K-1 )*WKM1 20 CONTINUE A( J, K ) = WK A( J, K-1 ) = WKM1 30 CONTINUE * END IF * END IF END IF * * Store details of the interchanges in IPIV * IF( KSTEP.EQ.1 ) THEN IPIV( K ) = KP ELSE IPIV( K ) = -KP IPIV( K-1 ) = -KP END IF * * Decrease K and return to the start of the main loop * K = K - KSTEP GO TO 10 * ELSE * * Factorize A as L*D*L**T using the lower triangle of A * * K is the main loop index, increasing from 1 to N in steps of * 1 or 2 * K = 1 40 CONTINUE * * If K > N, exit from loop * IF( K.GT.N ) $ GO TO 70 KSTEP = 1 * * Determine rows and columns to be interchanged and whether * a 1-by-1 or 2-by-2 pivot block will be used * ABSAKK = ABS( A( K, K ) ) * * IMAX is the row-index of the largest off-diagonal element in * column K, and COLMAX is its absolute value. * Determine both COLMAX and IMAX. * IF( K.LT.N ) THEN IMAX = K + IDAMAX( N-K, A( K+1, K ), 1 ) COLMAX = ABS( A( IMAX, K ) ) ELSE COLMAX = ZERO END IF * IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. $ DISNAN(ABSAKK) ) THEN * * Column K is zero or underflow, or contains a NaN: * set INFO and continue * IF( INFO.EQ.0 ) $ INFO = K KP = K ELSE IF( ABSAKK.GE.ALPHA*COLMAX ) THEN * * no interchange, use 1-by-1 pivot block * KP = K ELSE * * JMAX is the column-index of the largest off-diagonal * element in row IMAX, and ROWMAX is its absolute value * JMAX = K - 1 + IDAMAX( IMAX-K, A( IMAX, K ), LDA ) ROWMAX = ABS( A( IMAX, JMAX ) ) IF( IMAX.LT.N ) THEN JMAX = IMAX + IDAMAX( N-IMAX, A( IMAX+1, IMAX ), $ 1 ) ROWMAX = MAX( ROWMAX, ABS( A( JMAX, IMAX ) ) ) END IF * IF( ABSAKK.GE.ALPHA*COLMAX*( COLMAX / ROWMAX ) ) THEN * * no interchange, use 1-by-1 pivot block * KP = K ELSE IF( ABS( A( IMAX, IMAX ) ).GE.ALPHA*ROWMAX ) THEN * * interchange rows and columns K and IMAX, use 1-by-1 * pivot block * KP = IMAX ELSE * * interchange rows and columns K+1 and IMAX, use 2-by-2 * pivot block * KP = IMAX KSTEP = 2 END IF END IF * KK = K + KSTEP - 1 IF( KP.NE.KK ) THEN * * Interchange rows and columns KK and KP in the trailing * submatrix A(k:n,k:n) * IF( KP.LT.N ) $ CALL DSWAP( N-KP, A( KP+1, KK ), 1, A( KP+1, KP ), $ 1 ) CALL DSWAP( KP-KK-1, A( KK+1, KK ), 1, A( KP, KK+1 ), $ LDA ) T = A( KK, KK ) A( KK, KK ) = A( KP, KP ) A( KP, KP ) = T IF( KSTEP.EQ.2 ) THEN T = A( K+1, K ) A( K+1, K ) = A( KP, K ) A( KP, K ) = T END IF END IF * * Update the trailing submatrix * IF( KSTEP.EQ.1 ) THEN * * 1-by-1 pivot block D(k): column k now holds * * W(k) = L(k)*D(k) * * where L(k) is the k-th column of L * IF( K.LT.N ) THEN * * Perform a rank-1 update of A(k+1:n,k+1:n) as * * A := A - L(k)*D(k)*L(k)**T = A - W(k)*(1/D(k))*W(k)**T * D11 = ONE / A( K, K ) CALL DSYR( UPLO, N-K, -D11, A( K+1, K ), 1, $ A( K+1, K+1 ), LDA ) * * Store L(k) in column K * CALL DSCAL( N-K, D11, A( K+1, K ), 1 ) END IF ELSE * * 2-by-2 pivot block D(k) * IF( K.LT.N-1 ) THEN * * Perform a rank-2 update of A(k+2:n,k+2:n) as * * A := A - ( (A(k) A(k+1))*D(k)**(-1) ) * (A(k) A(k+1))**T * * where L(k) and L(k+1) are the k-th and (k+1)-th * columns of L * D21 = A( K+1, K ) D11 = A( K+1, K+1 ) / D21 D22 = A( K, K ) / D21 T = ONE / ( D11*D22-ONE ) D21 = T / D21 * DO 60 J = K + 2, N * WK = D21*( D11*A( J, K )-A( J, K+1 ) ) WKP1 = D21*( D22*A( J, K+1 )-A( J, K ) ) * DO 50 I = J, N A( I, J ) = A( I, J ) - A( I, K )*WK - $ A( I, K+1 )*WKP1 50 CONTINUE * A( J, K ) = WK A( J, K+1 ) = WKP1 * 60 CONTINUE END IF END IF END IF * * Store details of the interchanges in IPIV * IF( KSTEP.EQ.1 ) THEN IPIV( K ) = KP ELSE IPIV( K ) = -KP IPIV( K+1 ) = -KP END IF * * Increase K and return to the start of the main loop * K = K + KSTEP GO TO 40 * END IF * 70 CONTINUE * RETURN * * End of DSYTF2 * END *> \brief \b IDAMAX * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * INTEGER FUNCTION IDAMAX(N,DX,INCX) * * .. Scalar Arguments .. * INTEGER INCX,N * .. * .. Array Arguments .. * DOUBLE PRECISION DX(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> IDAMAX finds the index of the first element having maximum absolute value. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in] DX *> \verbatim *> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of DX *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup iamax * *> \par Further Details: * ===================== *> *> \verbatim *> *> jack dongarra, linpack, 3/11/78. *> modified 3/93 to return if incx .le. 0. *> modified 12/3/93, array(1) declarations changed to array(*) *> \endverbatim *> * ===================================================================== INTEGER FUNCTION IDAMAX(N,DX,INCX) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX,N * .. * .. Array Arguments .. DOUBLE PRECISION DX(*) * .. * * ===================================================================== * * .. Local Scalars .. DOUBLE PRECISION DMAX INTEGER I,IX * .. * .. Intrinsic Functions .. INTRINSIC DABS * .. IDAMAX = 0 IF (N.LT.1 .OR. INCX.LE.0) RETURN IDAMAX = 1 IF (N.EQ.1) RETURN IF (INCX.EQ.1) THEN * * code for increment equal to 1 * DMAX = DABS(DX(1)) DO I = 2,N IF (DABS(DX(I)).GT.DMAX) THEN IDAMAX = I DMAX = DABS(DX(I)) END IF END DO ELSE * * code for increment not equal to 1 * IX = 1 DMAX = DABS(DX(1)) IX = IX + INCX DO I = 2,N IF (DABS(DX(IX)).GT.DMAX) THEN IDAMAX = I DMAX = DABS(DX(IX)) END IF IX = IX + INCX END DO END IF RETURN * * End of IDAMAX * END *> \brief \b LSAME * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * LOGICAL FUNCTION LSAME(CA,CB) * * .. Scalar Arguments .. * CHARACTER CA,CB * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> LSAME returns .TRUE. if CA is the same letter as CB regardless of *> case. *> \endverbatim * * Arguments: * ========== * *> \param[in] CA *> \verbatim *> CA is CHARACTER*1 *> \endverbatim *> *> \param[in] CB *> \verbatim *> CB is CHARACTER*1 *> CA and CB specify the single characters to be compared. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup lsame * * ===================================================================== LOGICAL FUNCTION LSAME(CA,CB) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. CHARACTER CA,CB * .. * * ===================================================================== * * .. Intrinsic Functions .. INTRINSIC ICHAR * .. * .. Local Scalars .. INTEGER INTA,INTB,ZCODE * .. * * Test if the characters are equal * LSAME = CA .EQ. CB IF (LSAME) RETURN * * Now test for equivalence if both characters are alphabetic. * ZCODE = ICHAR('Z') * * Use 'Z' rather than 'A' so that ASCII can be detected on Prime * machines, on which ICHAR returns a value with bit 8 set. * ICHAR('A') on Prime machines returns 193 which is the same as * ICHAR('A') on an EBCDIC machine. * INTA = ICHAR(CA) INTB = ICHAR(CB) * IF (ZCODE.EQ.90 .OR. ZCODE.EQ.122) THEN * * ASCII is assumed - ZCODE is the ASCII code of either lower or * upper case 'Z'. * IF (INTA.GE.97 .AND. INTA.LE.122) INTA = INTA - 32 IF (INTB.GE.97 .AND. INTB.LE.122) INTB = INTB - 32 * ELSE IF (ZCODE.EQ.233 .OR. ZCODE.EQ.169) THEN * * EBCDIC is assumed - ZCODE is the EBCDIC code of either lower or * upper case 'Z'. * IF (INTA.GE.129 .AND. INTA.LE.137 .OR. + INTA.GE.145 .AND. INTA.LE.153 .OR. + INTA.GE.162 .AND. INTA.LE.169) INTA = INTA + 64 IF (INTB.GE.129 .AND. INTB.LE.137 .OR. + INTB.GE.145 .AND. INTB.LE.153 .OR. + INTB.GE.162 .AND. INTB.LE.169) INTB = INTB + 64 * ELSE IF (ZCODE.EQ.218 .OR. ZCODE.EQ.250) THEN * * ASCII is assumed, on Prime machines - ZCODE is the ASCII code * plus 128 of either lower or upper case 'Z'. * IF (INTA.GE.225 .AND. INTA.LE.250) INTA = INTA - 32 IF (INTB.GE.225 .AND. INTB.LE.250) INTB = INTB - 32 END IF LSAME = INTA .EQ. INTB * * RETURN * * End of LSAME * END *> \brief \b XERBLA * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE XERBLA( SRNAME, INFO ) * * .. Scalar Arguments .. * CHARACTER*(*) SRNAME * INTEGER INFO * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> XERBLA is an error handler for the LAPACK routines. *> It is called by an LAPACK routine if an input parameter has an *> invalid value. A message is printed and execution stops. *> *> Installers may consider modifying the STOP statement in order to *> call system-specific exception-handling facilities. *> \endverbatim * * Arguments: * ========== * *> \param[in] SRNAME *> \verbatim *> SRNAME is CHARACTER*(*) *> The name of the routine which called XERBLA. *> \endverbatim *> *> \param[in] INFO *> \verbatim *> INFO is INTEGER *> The position of the invalid parameter in the parameter list *> of the calling routine. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup xerbla * * ===================================================================== SUBROUTINE XERBLA( SRNAME, INFO ) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. CHARACTER*(*) SRNAME INTEGER INFO * .. * * ===================================================================== * * .. Intrinsic Functions .. INTRINSIC LEN_TRIM * .. * .. Executable Statements .. * WRITE( *, FMT = 9999 )SRNAME( 1:LEN_TRIM( SRNAME ) ), INFO * STOP * 9999 FORMAT( ' ** On entry to ', A, ' parameter number ', I2, ' had ', $ 'an illegal value' ) * * End of XERBLA * END