dtpmv (l)  Linux Man Pages
dtpmv: performs one of the matrixvector operations x := A*x, or x := Aaq*x,
NAME
DTPMV  performs one of the matrixvector operations x := A*x, or x := Aaq*x,SYNOPSIS
 SUBROUTINE DTPMV(UPLO,TRANS,DIAG,N,AP,X,INCX)
 INTEGER INCX,N
 CHARACTER DIAG,TRANS,UPLO
 DOUBLE PRECISION AP(*),X(*)
PURPOSE
DTPMV performs one of the matrixvector operationswhere x is an n element vector and A is an n by n unit, or nonunit, 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 = aqUaq or aquaq A is an upper triangular matrix.
UPLO = aqLaq or aqlaq A is a lower triangular matrix.
Unchanged on exit.
 TRANS  CHARACTER*1.

On entry, TRANS specifies the operation to be performed as
follows:
TRANS = aqNaq or aqnaq x := A*x.
TRANS = aqTaq or aqtaq x := Aaq*x.
TRANS = aqCaq or aqcaq x := Aaq*x.
Unchanged on exit.
 DIAG  CHARACTER*1.

On entry, DIAG specifies whether or not A is unit
triangular as follows:
DIAG = aqUaq or aquaq A is assumed to be unit triangular.
DIAG = aqNaq or aqnaq 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 = aqUaq or aquaq, 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 = aqLaq or aqlaq, 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 = aqUaq or aquaq, 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 22October1986.
Jack Dongarra, Argonne National Lab.
Jeremy Du Croz, Nag Central Office.
Sven Hammarling, Nag Central Office.
Richard Hanson, Sandia National Labs.