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authorjason <jason@8a072113-8704-0410-8d35-dd094bca7971>2008-10-28 01:38:50 +0000
committerjason <jason@8a072113-8704-0410-8d35-dd094bca7971>2008-10-28 01:38:50 +0000
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Move LAPACK trunk into position.
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+ SUBROUTINE CHEMV(UPLO,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY)
+* .. Scalar Arguments ..
+ COMPLEX ALPHA,BETA
+ INTEGER INCX,INCY,LDA,N
+ CHARACTER UPLO
+* ..
+* .. Array Arguments ..
+ COMPLEX A(LDA,*),X(*),Y(*)
+* ..
+*
+* Purpose
+* =======
+*
+* CHEMV performs the matrix-vector operation
+*
+* y := alpha*A*x + beta*y,
+*
+* where alpha and beta are scalars, x and y are n element vectors and
+* A is an n by n hermitian matrix.
+*
+* Arguments
+* ==========
+*
+* 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 .
+* On entry, ALPHA specifies the scalar alpha.
+* Unchanged on exit.
+*
+* A - COMPLEX 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.
+* 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.
+* Note that the imaginary parts of the diagonal elements need
+* not be set and are assumed to be zero.
+* Unchanged on exit.
+*
+* 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.
+*
+* X - COMPLEX 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.
+*
+* BETA - COMPLEX .
+* On entry, BETA specifies the scalar beta. When BETA is
+* supplied as zero then Y need not be set on input.
+* Unchanged on exit.
+*
+* Y - COMPLEX array of dimension at least
+* ( 1 + ( n - 1 )*abs( INCY ) ).
+* Before entry, the incremented array Y must contain the n
+* element vector y. On exit, Y is overwritten by the updated
+* vector y.
+*
+* INCY - INTEGER.
+* On entry, INCY specifies the increment for the elements of
+* Y. INCY must not be zero.
+* 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 ONE
+ PARAMETER (ONE= (1.0E+0,0.0E+0))
+ COMPLEX ZERO
+ PARAMETER (ZERO= (0.0E+0,0.0E+0))
+* ..
+* .. Local Scalars ..
+ COMPLEX 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 CONJG,MAX,REAL
+* ..
+*
+* 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 (LDA.LT.MAX(1,N)) THEN
+ INFO = 5
+ ELSE IF (INCX.EQ.0) THEN
+ INFO = 7
+ ELSE IF (INCY.EQ.0) THEN
+ INFO = 10
+ END IF
+ IF (INFO.NE.0) THEN
+ CALL XERBLA('CHEMV ',INFO)
+ RETURN
+ END IF
+*
+* Quick return if possible.
+*
+ IF ((N.EQ.0) .OR. ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN
+*
+* Set up the start points in X and Y.
+*
+ 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
+*
+* Start the operations. In this version the elements of A are
+* accessed sequentially with one pass through the triangular part
+* of A.
+*
+* First form y := beta*y.
+*
+ IF (BETA.NE.ONE) THEN
+ IF (INCY.EQ.1) THEN
+ IF (BETA.EQ.ZERO) THEN
+ DO 10 I = 1,N
+ Y(I) = ZERO
+ 10 CONTINUE
+ ELSE
+ DO 20 I = 1,N
+ Y(I) = BETA*Y(I)
+ 20 CONTINUE
+ END IF
+ ELSE
+ IY = KY
+ IF (BETA.EQ.ZERO) THEN
+ DO 30 I = 1,N
+ Y(IY) = ZERO
+ IY = IY + INCY
+ 30 CONTINUE
+ ELSE
+ DO 40 I = 1,N
+ Y(IY) = BETA*Y(IY)
+ IY = IY + INCY
+ 40 CONTINUE
+ END IF
+ END IF
+ END IF
+ IF (ALPHA.EQ.ZERO) RETURN
+ IF (LSAME(UPLO,'U')) THEN
+*
+* Form y when A is stored in upper triangle.
+*
+ IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN
+ DO 60 J = 1,N
+ TEMP1 = ALPHA*X(J)
+ TEMP2 = ZERO
+ DO 50 I = 1,J - 1
+ Y(I) = Y(I) + TEMP1*A(I,J)
+ TEMP2 = TEMP2 + CONJG(A(I,J))*X(I)
+ 50 CONTINUE
+ Y(J) = Y(J) + TEMP1*REAL(A(J,J)) + ALPHA*TEMP2
+ 60 CONTINUE
+ ELSE
+ JX = KX
+ JY = KY
+ DO 80 J = 1,N
+ TEMP1 = ALPHA*X(JX)
+ TEMP2 = ZERO
+ IX = KX
+ IY = KY
+ DO 70 I = 1,J - 1
+ Y(IY) = Y(IY) + TEMP1*A(I,J)
+ TEMP2 = TEMP2 + CONJG(A(I,J))*X(IX)
+ IX = IX + INCX
+ IY = IY + INCY
+ 70 CONTINUE
+ Y(JY) = Y(JY) + TEMP1*REAL(A(J,J)) + ALPHA*TEMP2
+ JX = JX + INCX
+ JY = JY + INCY
+ 80 CONTINUE
+ END IF
+ ELSE
+*
+* Form y when A is stored in lower triangle.
+*
+ IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN
+ DO 100 J = 1,N
+ TEMP1 = ALPHA*X(J)
+ TEMP2 = ZERO
+ Y(J) = Y(J) + TEMP1*REAL(A(J,J))
+ DO 90 I = J + 1,N
+ Y(I) = Y(I) + TEMP1*A(I,J)
+ TEMP2 = TEMP2 + CONJG(A(I,J))*X(I)
+ 90 CONTINUE
+ Y(J) = Y(J) + ALPHA*TEMP2
+ 100 CONTINUE
+ ELSE
+ JX = KX
+ JY = KY
+ DO 120 J = 1,N
+ TEMP1 = ALPHA*X(JX)
+ TEMP2 = ZERO
+ Y(JY) = Y(JY) + TEMP1*REAL(A(J,J))
+ IX = JX
+ IY = JY
+ DO 110 I = J + 1,N
+ IX = IX + INCX
+ IY = IY + INCY
+ Y(IY) = Y(IY) + TEMP1*A(I,J)
+ TEMP2 = TEMP2 + CONJG(A(I,J))*X(IX)
+ 110 CONTINUE
+ Y(JY) = Y(JY) + ALPHA*TEMP2
+ JX = JX + INCX
+ JY = JY + INCY
+ 120 CONTINUE
+ END IF
+ END IF
+*
+ RETURN
+*
+* End of CHEMV .
+*
+ END