
DTPMV(l) BLAS routine DTPMV(l)
NAME
DTPMV  perform one of the matrixvector operations x := A*x, or x := A'*x,
SYNOPSIS
SUBROUTINE DTPMV ( UPLO, TRANS, DIAG, N, AP, X, INCX )
INTEGER INCX, N
CHARACTER*1 DIAG, TRANS, UPLO
DOUBLE PRECISION AP( * ), X( * )
PURPOSE
DTPMV performs one of the matrixvector operations
where x is an n element vector and A is an n by n unit, or nonunit, upper or lower tri
angular matrix, supplied in packed form.
PARAMETERS
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.
Level 2 Blas routine.
 Written on 22October1986. Jack Dongarra, Argonne National Lab. Jeremy Du
Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson,
Sandia National Labs.
BLAS routine 16 October 1992 DTPMV(l) 
