diff options
Diffstat (limited to '2.3-1/src/fortran/blas/zher2.f')
| -rw-r--r-- | 2.3-1/src/fortran/blas/zher2.f | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/blas/zher2.f b/2.3-1/src/fortran/blas/zher2.f new file mode 100644 index 00000000..06acdff7 --- /dev/null +++ b/2.3-1/src/fortran/blas/zher2.f @@ -0,0 +1,249 @@ + SUBROUTINE ZHER2 ( UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA ) +* .. Scalar Arguments .. + COMPLEX*16 ALPHA + INTEGER INCX, INCY, LDA, N + CHARACTER*1 UPLO +* .. Array Arguments .. + COMPLEX*16 A( LDA, * ), X( * ), Y( * ) +* .. +* +* Purpose +* ======= +* +* ZHER2 performs the hermitian rank 2 operation +* +* A := alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + A, +* +* where alpha is a scalar, x and y are n element vectors and A is an n +* by n hermitian matrix. +* +* Parameters +* ========== +* +* UPLO - 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. +* +* Unchanged on exit. +* +* N - INTEGER. +* On entry, N specifies the order of the matrix A. +* N must be at least zero. +* Unchanged on exit. +* +* ALPHA - COMPLEX*16 . +* On entry, ALPHA specifies the scalar alpha. +* Unchanged on exit. +* +* X - COMPLEX*16 array of dimension at least +* ( 1 + ( n - 1 )*abs( INCX ) ). +* Before entry, the incremented array X must contain the n +* element vector x. +* Unchanged on exit. +* +* INCX - INTEGER. +* On entry, INCX specifies the increment for the elements of +* X. INCX must not be zero. +* Unchanged on exit. +* +* Y - COMPLEX*16 array of dimension at least +* ( 1 + ( n - 1 )*abs( INCY ) ). +* Before entry, the incremented array Y must contain the n +* element vector y. +* Unchanged on exit. +* +* INCY - INTEGER. +* On entry, INCY specifies the increment for the elements of +* Y. INCY must not be zero. +* Unchanged on exit. +* +* A - COMPLEX*16 array of 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 hermitian 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 hermitian 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. +* Note that the imaginary parts of the diagonal elements need +* not be set, they are assumed to be zero, and on exit they +* are set to zero. +* +* LDA - 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 ). +* Unchanged on exit. +* +* +* 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. +* +* +* .. Parameters .. + COMPLEX*16 ZERO + PARAMETER ( ZERO = ( 0.0D+0, 0.0D+0 ) ) +* .. Local Scalars .. + COMPLEX*16 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 DCONJG, MAX, DBLE +* .. +* .. Executable Statements .. +* +* 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( 'ZHER2 ', 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*DCONJG( Y( J ) ) + TEMP2 = DCONJG( ALPHA*X( J ) ) + DO 10, I = 1, J - 1 + A( I, J ) = A( I, J ) + X( I )*TEMP1 + Y( I )*TEMP2 + 10 CONTINUE + A( J, J ) = DBLE( A( J, J ) ) + + $ DBLE( X( J )*TEMP1 + Y( J )*TEMP2 ) + ELSE + A( J, J ) = DBLE( A( J, J ) ) + END IF + 20 CONTINUE + ELSE + DO 40, J = 1, N + IF( ( X( JX ).NE.ZERO ).OR.( Y( JY ).NE.ZERO ) )THEN + TEMP1 = ALPHA*DCONJG( Y( JY ) ) + TEMP2 = DCONJG( ALPHA*X( JX ) ) + IX = KX + IY = KY + DO 30, I = 1, J - 1 + A( I, J ) = A( I, J ) + X( IX )*TEMP1 + $ + Y( IY )*TEMP2 + IX = IX + INCX + IY = IY + INCY + 30 CONTINUE + A( J, J ) = DBLE( A( J, J ) ) + + $ DBLE( X( JX )*TEMP1 + Y( JY )*TEMP2 ) + ELSE + A( J, J ) = DBLE( A( J, J ) ) + 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*DCONJG( Y( J ) ) + TEMP2 = DCONJG( ALPHA*X( J ) ) + A( J, J ) = DBLE( A( J, J ) ) + + $ DBLE( X( J )*TEMP1 + Y( J )*TEMP2 ) + DO 50, I = J + 1, N + A( I, J ) = A( I, J ) + X( I )*TEMP1 + Y( I )*TEMP2 + 50 CONTINUE + ELSE + A( J, J ) = DBLE( A( J, J ) ) + END IF + 60 CONTINUE + ELSE + DO 80, J = 1, N + IF( ( X( JX ).NE.ZERO ).OR.( Y( JY ).NE.ZERO ) )THEN + TEMP1 = ALPHA*DCONJG( Y( JY ) ) + TEMP2 = DCONJG( ALPHA*X( JX ) ) + A( J, J ) = DBLE( A( J, J ) ) + + $ DBLE( X( JX )*TEMP1 + Y( JY )*TEMP2 ) + IX = JX + IY = JY + DO 70, I = J + 1, N + IX = IX + INCX + IY = IY + INCY + A( I, J ) = A( I, J ) + X( IX )*TEMP1 + $ + Y( IY )*TEMP2 + 70 CONTINUE + ELSE + A( J, J ) = DBLE( A( J, J ) ) + END IF + JX = JX + INCX + JY = JY + INCY + 80 CONTINUE + END IF + END IF +* + RETURN +* +* End of ZHER2 . +* + END |