From db464f35f5a10b58d9ed1085e0b462689adee583 Mon Sep 17 00:00:00 2001 From: Siddhesh Wani Date: Mon, 25 May 2015 14:46:31 +0530 Subject: Original Version --- src/fortran/blas/dgbmv.f | 300 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 300 insertions(+) create mode 100644 src/fortran/blas/dgbmv.f (limited to 'src/fortran/blas/dgbmv.f') diff --git a/src/fortran/blas/dgbmv.f b/src/fortran/blas/dgbmv.f new file mode 100644 index 00000000..e9c8f76f --- /dev/null +++ b/src/fortran/blas/dgbmv.f @@ -0,0 +1,300 @@ + SUBROUTINE DGBMV ( TRANS, M, N, KL, KU, ALPHA, A, LDA, X, INCX, + $ BETA, Y, INCY ) +* .. Scalar Arguments .. + DOUBLE PRECISION ALPHA, BETA + INTEGER INCX, INCY, KL, KU, LDA, M, N + CHARACTER*1 TRANS +* .. Array Arguments .. + DOUBLE PRECISION A( LDA, * ), X( * ), Y( * ) +* .. +* +* Purpose +* ======= +* +* DGBMV performs one of the matrix-vector operations +* +* y := alpha*A*x + beta*y, or y := alpha*A'*x + beta*y, +* +* where alpha and beta are scalars, x and y are vectors and A is an +* m by n band matrix, with kl sub-diagonals and ku super-diagonals. +* +* Parameters +* ========== +* +* TRANS - CHARACTER*1. +* On entry, TRANS specifies the operation to be performed as +* follows: +* +* TRANS = 'N' or 'n' y := alpha*A*x + beta*y. +* +* TRANS = 'T' or 't' y := alpha*A'*x + beta*y. +* +* TRANS = 'C' or 'c' y := alpha*A'*x + beta*y. +* +* Unchanged on exit. +* +* M - INTEGER. +* On entry, M specifies the number of rows of the matrix A. +* M must be at least zero. +* Unchanged on exit. +* +* N - INTEGER. +* On entry, N specifies the number of columns of the matrix A. +* N must be at least zero. +* Unchanged on exit. +* +* KL - INTEGER. +* On entry, KL specifies the number of sub-diagonals of the +* matrix A. KL must satisfy 0 .le. KL. +* Unchanged on exit. +* +* KU - INTEGER. +* On entry, KU specifies the number of super-diagonals of the +* matrix A. KU must satisfy 0 .le. KU. +* Unchanged on exit. +* +* ALPHA - DOUBLE PRECISION. +* On entry, ALPHA specifies the scalar alpha. +* Unchanged on exit. +* +* A - DOUBLE PRECISION array of DIMENSION ( LDA, n ). +* Before entry, the leading ( kl + ku + 1 ) by n part of the +* array A must contain the matrix of coefficients, supplied +* column by column, with the leading diagonal of the matrix in +* row ( ku + 1 ) of the array, the first super-diagonal +* starting at position 2 in row ku, the first sub-diagonal +* starting at position 1 in row ( ku + 2 ), and so on. +* Elements in the array A that do not correspond to elements +* in the band matrix (such as the top left ku by ku triangle) +* are not referenced. +* The following program segment will transfer a band matrix +* from conventional full matrix storage to band storage: +* +* DO 20, J = 1, N +* K = KU + 1 - J +* DO 10, I = MAX( 1, J - KU ), MIN( M, J + KL ) +* A( K + I, J ) = matrix( I, J ) +* 10 CONTINUE +* 20 CONTINUE +* +* 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 +* ( kl + ku + 1 ). +* Unchanged on exit. +* +* X - DOUBLE PRECISION array of DIMENSION at least +* ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n' +* and at least +* ( 1 + ( m - 1 )*abs( INCX ) ) otherwise. +* Before entry, the incremented array X must contain the +* 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 - DOUBLE PRECISION. +* 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 - DOUBLE PRECISION array of DIMENSION at least +* ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n' +* and at least +* ( 1 + ( n - 1 )*abs( INCY ) ) otherwise. +* Before entry, the incremented array Y must contain the +* 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 .. + DOUBLE PRECISION ONE , ZERO + PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) +* .. Local Scalars .. + DOUBLE PRECISION TEMP + INTEGER I, INFO, IX, IY, J, JX, JY, K, KUP1, KX, KY, + $ LENX, LENY +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. External Subroutines .. + EXTERNAL XERBLA +* .. Intrinsic Functions .. + INTRINSIC MAX, MIN +* .. +* .. Executable Statements .. +* +* Test the input parameters. +* + INFO = 0 + IF ( .NOT.LSAME( TRANS, 'N' ).AND. + $ .NOT.LSAME( TRANS, 'T' ).AND. + $ .NOT.LSAME( TRANS, 'C' ) )THEN + INFO = 1 + ELSE IF( M.LT.0 )THEN + INFO = 2 + ELSE IF( N.LT.0 )THEN + INFO = 3 + ELSE IF( KL.LT.0 )THEN + INFO = 4 + ELSE IF( KU.LT.0 )THEN + INFO = 5 + ELSE IF( LDA.LT.( KL + KU + 1 ) )THEN + INFO = 8 + ELSE IF( INCX.EQ.0 )THEN + INFO = 10 + ELSE IF( INCY.EQ.0 )THEN + INFO = 13 + END IF + IF( INFO.NE.0 )THEN + CALL XERBLA( 'DGBMV ', INFO ) + RETURN + END IF +* +* Quick return if possible. +* + IF( ( M.EQ.0 ).OR.( N.EQ.0 ).OR. + $ ( ( ALPHA.EQ.ZERO ).AND.( BETA.EQ.ONE ) ) ) + $ RETURN +* +* Set LENX and LENY, the lengths of the vectors x and y, and set +* up the start points in X and Y. +* + IF( LSAME( TRANS, 'N' ) )THEN + LENX = N + LENY = M + ELSE + LENX = M + LENY = N + END IF + IF( INCX.GT.0 )THEN + KX = 1 + ELSE + KX = 1 - ( LENX - 1 )*INCX + END IF + IF( INCY.GT.0 )THEN + KY = 1 + ELSE + KY = 1 - ( LENY - 1 )*INCY + END IF +* +* Start the operations. In this version the elements of A are +* accessed sequentially with one pass through the band 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, LENY + Y( I ) = ZERO + 10 CONTINUE + ELSE + DO 20, I = 1, LENY + Y( I ) = BETA*Y( I ) + 20 CONTINUE + END IF + ELSE + IY = KY + IF( BETA.EQ.ZERO )THEN + DO 30, I = 1, LENY + Y( IY ) = ZERO + IY = IY + INCY + 30 CONTINUE + ELSE + DO 40, I = 1, LENY + Y( IY ) = BETA*Y( IY ) + IY = IY + INCY + 40 CONTINUE + END IF + END IF + END IF + IF( ALPHA.EQ.ZERO ) + $ RETURN + KUP1 = KU + 1 + IF( LSAME( TRANS, 'N' ) )THEN +* +* Form y := alpha*A*x + y. +* + JX = KX + IF( INCY.EQ.1 )THEN + DO 60, J = 1, N + IF( X( JX ).NE.ZERO )THEN + TEMP = ALPHA*X( JX ) + K = KUP1 - J + DO 50, I = MAX( 1, J - KU ), MIN( M, J + KL ) + Y( I ) = Y( I ) + TEMP*A( K + I, J ) + 50 CONTINUE + END IF + JX = JX + INCX + 60 CONTINUE + ELSE + DO 80, J = 1, N + IF( X( JX ).NE.ZERO )THEN + TEMP = ALPHA*X( JX ) + IY = KY + K = KUP1 - J + DO 70, I = MAX( 1, J - KU ), MIN( M, J + KL ) + Y( IY ) = Y( IY ) + TEMP*A( K + I, J ) + IY = IY + INCY + 70 CONTINUE + END IF + JX = JX + INCX + IF( J.GT.KU ) + $ KY = KY + INCY + 80 CONTINUE + END IF + ELSE +* +* Form y := alpha*A'*x + y. +* + JY = KY + IF( INCX.EQ.1 )THEN + DO 100, J = 1, N + TEMP = ZERO + K = KUP1 - J + DO 90, I = MAX( 1, J - KU ), MIN( M, J + KL ) + TEMP = TEMP + A( K + I, J )*X( I ) + 90 CONTINUE + Y( JY ) = Y( JY ) + ALPHA*TEMP + JY = JY + INCY + 100 CONTINUE + ELSE + DO 120, J = 1, N + TEMP = ZERO + IX = KX + K = KUP1 - J + DO 110, I = MAX( 1, J - KU ), MIN( M, J + KL ) + TEMP = TEMP + A( K + I, J )*X( IX ) + IX = IX + INCX + 110 CONTINUE + Y( JY ) = Y( JY ) + ALPHA*TEMP + JY = JY + INCY + IF( J.GT.KU ) + $ KX = KX + INCX + 120 CONTINUE + END IF + END IF +* + RETURN +* +* End of DGBMV . +* + END -- cgit