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Diffstat (limited to 'blas/dtpmv.f')
| -rw-r--r-- | blas/dtpmv.f | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/blas/dtpmv.f b/blas/dtpmv.f new file mode 100644 index 000000000..c5bc112dc --- /dev/null +++ b/blas/dtpmv.f @@ -0,0 +1,293 @@ + SUBROUTINE DTPMV(UPLO,TRANS,DIAG,N,AP,X,INCX) +* .. Scalar Arguments .. + INTEGER INCX,N + CHARACTER DIAG,TRANS,UPLO +* .. +* .. Array Arguments .. + DOUBLE PRECISION AP(*),X(*) +* .. +* +* Purpose +* ======= +* +* DTPMV performs one of the matrix-vector operations +* +* x := A*x, or x := A'*x, +* +* where x is an n element vector and A is an n by n unit, or non-unit, +* upper or lower triangular matrix, supplied in packed form. +* +* Arguments +* ========== +* +* UPLO - CHARACTER*1. +* On entry, UPLO specifies whether the matrix is an upper or +* lower triangular matrix as follows: +* +* UPLO = 'U' or 'u' A is an upper triangular matrix. +* +* UPLO = 'L' or 'l' A is a lower triangular matrix. +* +* Unchanged on exit. +* +* TRANS - CHARACTER*1. +* On entry, TRANS specifies the operation to be performed as +* follows: +* +* TRANS = 'N' or 'n' x := A*x. +* +* TRANS = 'T' or 't' x := A'*x. +* +* TRANS = 'C' or 'c' x := A'*x. +* +* Unchanged on exit. +* +* DIAG - CHARACTER*1. +* On entry, DIAG specifies whether or not A is unit +* triangular as follows: +* +* DIAG = 'U' or 'u' A is assumed to be unit triangular. +* +* DIAG = 'N' or 'n' A is not assumed to be unit +* triangular. +* +* Unchanged on exit. +* +* N - INTEGER. +* On entry, N specifies the order of the matrix A. +* N must be at least zero. +* Unchanged on exit. +* +* AP - DOUBLE PRECISION array of DIMENSION at least +* ( ( n*( n + 1 ) )/2 ). +* Before entry with UPLO = 'U' or 'u', the array AP must +* contain the upper triangular matrix packed sequentially, +* column by column, so that AP( 1 ) contains a( 1, 1 ), +* AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) +* respectively, and so on. +* Before entry with UPLO = 'L' or 'l', the array AP must +* contain the lower triangular matrix packed sequentially, +* column by column, so that AP( 1 ) contains a( 1, 1 ), +* AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) +* respectively, and so on. +* Note that when DIAG = 'U' or 'u', the diagonal elements of +* A are not referenced, but are assumed to be unity. +* Unchanged on exit. +* +* X - DOUBLE PRECISION array of dimension at least +* ( 1 + ( n - 1 )*abs( INCX ) ). +* Before entry, the incremented array X must contain the n +* element vector x. On exit, X is overwritten with the +* tranformed vector x. +* +* INCX - INTEGER. +* On entry, INCX specifies the increment for the elements of +* X. INCX must not be zero. +* Unchanged on exit. +* +* Further Details +* =============== +* +* 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 .. + DOUBLE PRECISION ZERO + PARAMETER (ZERO=0.0D+0) +* .. +* .. Local Scalars .. + DOUBLE PRECISION TEMP + INTEGER I,INFO,IX,J,JX,K,KK,KX + LOGICAL NOUNIT +* .. +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. +* .. External Subroutines .. + EXTERNAL XERBLA +* .. +* +* Test the input parameters. +* + INFO = 0 + IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN + INFO = 1 + ELSE IF (.NOT.LSAME(TRANS,'N') .AND. .NOT.LSAME(TRANS,'T') .AND. + + .NOT.LSAME(TRANS,'C')) THEN + INFO = 2 + ELSE IF (.NOT.LSAME(DIAG,'U') .AND. .NOT.LSAME(DIAG,'N')) THEN + INFO = 3 + ELSE IF (N.LT.0) THEN + INFO = 4 + ELSE IF (INCX.EQ.0) THEN + INFO = 7 + END IF + IF (INFO.NE.0) THEN + CALL XERBLA('DTPMV ',INFO) + RETURN + END IF +* +* Quick return if possible. +* + IF (N.EQ.0) RETURN +* + NOUNIT = LSAME(DIAG,'N') +* +* Set up the start point in X if the increment is not unity. This +* will be ( N - 1 )*INCX too small for descending loops. +* + 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 AP are +* accessed sequentially with one pass through AP. +* + IF (LSAME(TRANS,'N')) THEN +* +* Form x:= A*x. +* + IF (LSAME(UPLO,'U')) THEN + KK = 1 + IF (INCX.EQ.1) THEN + DO 20 J = 1,N + IF (X(J).NE.ZERO) THEN + TEMP = X(J) + K = KK + DO 10 I = 1,J - 1 + X(I) = X(I) + TEMP*AP(K) + K = K + 1 + 10 CONTINUE + IF (NOUNIT) X(J) = X(J)*AP(KK+J-1) + END IF + KK = KK + J + 20 CONTINUE + ELSE + JX = KX + DO 40 J = 1,N + IF (X(JX).NE.ZERO) THEN + TEMP = X(JX) + IX = KX + DO 30 K = KK,KK + J - 2 + X(IX) = X(IX) + TEMP*AP(K) + IX = IX + INCX + 30 CONTINUE + IF (NOUNIT) X(JX) = X(JX)*AP(KK+J-1) + END IF + JX = JX + INCX + KK = KK + J + 40 CONTINUE + END IF + ELSE + KK = (N* (N+1))/2 + IF (INCX.EQ.1) THEN + DO 60 J = N,1,-1 + IF (X(J).NE.ZERO) THEN + TEMP = X(J) + K = KK + DO 50 I = N,J + 1,-1 + X(I) = X(I) + TEMP*AP(K) + K = K - 1 + 50 CONTINUE + IF (NOUNIT) X(J) = X(J)*AP(KK-N+J) + END IF + KK = KK - (N-J+1) + 60 CONTINUE + ELSE + KX = KX + (N-1)*INCX + JX = KX + DO 80 J = N,1,-1 + IF (X(JX).NE.ZERO) THEN + TEMP = X(JX) + IX = KX + DO 70 K = KK,KK - (N- (J+1)),-1 + X(IX) = X(IX) + TEMP*AP(K) + IX = IX - INCX + 70 CONTINUE + IF (NOUNIT) X(JX) = X(JX)*AP(KK-N+J) + END IF + JX = JX - INCX + KK = KK - (N-J+1) + 80 CONTINUE + END IF + END IF + ELSE +* +* Form x := A'*x. +* + IF (LSAME(UPLO,'U')) THEN + KK = (N* (N+1))/2 + IF (INCX.EQ.1) THEN + DO 100 J = N,1,-1 + TEMP = X(J) + IF (NOUNIT) TEMP = TEMP*AP(KK) + K = KK - 1 + DO 90 I = J - 1,1,-1 + TEMP = TEMP + AP(K)*X(I) + K = K - 1 + 90 CONTINUE + X(J) = TEMP + KK = KK - J + 100 CONTINUE + ELSE + JX = KX + (N-1)*INCX + DO 120 J = N,1,-1 + TEMP = X(JX) + IX = JX + IF (NOUNIT) TEMP = TEMP*AP(KK) + DO 110 K = KK - 1,KK - J + 1,-1 + IX = IX - INCX + TEMP = TEMP + AP(K)*X(IX) + 110 CONTINUE + X(JX) = TEMP + JX = JX - INCX + KK = KK - J + 120 CONTINUE + END IF + ELSE + KK = 1 + IF (INCX.EQ.1) THEN + DO 140 J = 1,N + TEMP = X(J) + IF (NOUNIT) TEMP = TEMP*AP(KK) + K = KK + 1 + DO 130 I = J + 1,N + TEMP = TEMP + AP(K)*X(I) + K = K + 1 + 130 CONTINUE + X(J) = TEMP + KK = KK + (N-J+1) + 140 CONTINUE + ELSE + JX = KX + DO 160 J = 1,N + TEMP = X(JX) + IX = JX + IF (NOUNIT) TEMP = TEMP*AP(KK) + DO 150 K = KK + 1,KK + N - J + IX = IX + INCX + TEMP = TEMP + AP(K)*X(IX) + 150 CONTINUE + X(JX) = TEMP + JX = JX + INCX + KK = KK + (N-J+1) + 160 CONTINUE + END IF + END IF + END IF +* + RETURN +* +* End of DTPMV . +* + END |