Numérotation des lignes :

dsyr2
C DSYR2     SOURCE    BP208322  22/09/16    21:15:07     11454          *> \brief \b DSYR2**  =========== DOCUMENTATION ===========** Online html documentation available at*            http://www.netlib.org/lapack/explore-html/**  Definition:*  ===========**       SUBROUTINE DSYR2(UPLO,N,ALPHA,X,INCX,Y,INCY,A,LDA)**       .. Scalar Arguments ..*       REAL*8 ALPHA*       INTEGER INCX,INCY,LDA,N*       CHARACTER UPLO*       ..*       .. Array Arguments ..*       REAL*8 A(LDA,*),X(*),Y(*)*       ..***> \par Purpose:*  =============*>*> \verbatim*>*> DSYR2  performs the symmetric rank 2 operation*>*>    A := alpha*x*y**T + alpha*y*x**T + A,*>*> where alpha is a scalar, x and y are n element vectors 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 REAL*8.*>           On entry, ALPHA specifies the scalar alpha.*> \endverbatim*>*> \param[in] X*> \verbatim*>          X is REAL*8 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] Y*> \verbatim*>          Y is REAL*8 array, dimension at least*>           ( 1 + ( n - 1 )*abs( INCY ) ).*>           Before entry, the incremented array Y must contain the n*>           element vector y.*> \endverbatim*>*> \param[in] INCY*> \verbatim*>          INCY is INTEGER*>           On entry, INCY specifies the increment for the elements of*>           Y. INCY must not be zero.*> \endverbatim*>*> \param[in,out] A*> \verbatim*>          A is REAL*8 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 double_blas_level2**> \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 DSYR2(UPLO,N,ALPHA,X,INCX,Y,INCY,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 ..      REAL*8 ALPHA      INTEGER INCX,INCY,LDA,N      CHARACTER UPLO*     ..*     .. Array Arguments ..      REAL*8 A(LDA,*),X(*),Y(*)*     ..**  =====================================================================**     .. Parameters ..      REAL*8 ZERO      PARAMETER (ZERO=0.0D+0)*     ..*     .. Local Scalars ..      REAL*8 TEMP1,TEMP2      INTEGER I,INFO,IX,IY,J,JX,JY,KX,KY*     ..*     .. 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 (INCY.EQ.0) THEN          INFO = 7      ELSE IF (LDA.LT.MAX(1,N)) THEN          INFO = 9      END IF      IF (INFO.NE.0) THEN          CALL XERBLA('DSYR2 ',INFO)          RETURN      END IF**     Quick return if possible.*      IF ((N.EQ.0) .OR. (ALPHA.EQ.ZERO)) RETURN**     Set up the start points in X and Y if the increments are not both*     unity.*      IF ((INCX.NE.1) .OR. (INCY.NE.1)) THEN          IF (INCX.GT.0) THEN              KX = 1          ELSE              KX = 1 - (N-1)*INCX          END IF          IF (INCY.GT.0) THEN              KY = 1          ELSE              KY = 1 - (N-1)*INCY          END IF          JX = KX          JY = KY      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 the upper triangle.*          IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN              DO 20 J = 1,N                  IF ((X(J).NE.ZERO) .OR. (Y(J).NE.ZERO)) THEN                      TEMP1 = ALPHA*Y(J)                      TEMP2 = ALPHA*X(J)                      DO 10 I = 1,J                          A(I,J) = A(I,J) + X(I)*TEMP1 + Y(I)*TEMP2   10                 CONTINUE                  END IF   20         CONTINUE          ELSE              DO 40 J = 1,N                  IF ((X(JX).NE.ZERO) .OR. (Y(JY).NE.ZERO)) THEN                      TEMP1 = ALPHA*Y(JY)                      TEMP2 = ALPHA*X(JX)                      IX = KX                      IY = KY                      DO 30 I = 1,J                          A(I,J) = A(I,J) + X(IX)*TEMP1 + Y(IY)*TEMP2                          IX = IX + INCX                          IY = IY + INCY   30                 CONTINUE                  END IF                  JX = JX + INCX                  JY = JY + INCY   40         CONTINUE          END IF      ELSE**        Form  A  when A is stored in the lower triangle.*          IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN              DO 60 J = 1,N                  IF ((X(J).NE.ZERO) .OR. (Y(J).NE.ZERO)) THEN                      TEMP1 = ALPHA*Y(J)                      TEMP2 = ALPHA*X(J)                      DO 50 I = J,N                          A(I,J) = A(I,J) + X(I)*TEMP1 + Y(I)*TEMP2   50                 CONTINUE                  END IF   60         CONTINUE          ELSE              DO 80 J = 1,N                  IF ((X(JX).NE.ZERO) .OR. (Y(JY).NE.ZERO)) THEN                      TEMP1 = ALPHA*Y(JY)                      TEMP2 = ALPHA*X(JX)                      IX = JX                      IY = JY                      DO 70 I = J,N                          A(I,J) = A(I,J) + X(IX)*TEMP1 + Y(IY)*TEMP2                          IX = IX + INCX                          IY = IY + INCY   70                 CONTINUE                  END IF                  JX = JX + INCX                  JY = JY + INCY   80         CONTINUE          END IF      END IF*      RETURN**     End of DSYR2*      END  

© Cast3M 2003 - Tous droits réservés.
Mentions légales