dtrmv()

subroutine dtrmv	(	character	uplo,
		character	trans,
		character	diag,
		integer	n,
		double precision, dimension(lda,*)	a,
		integer	lda,
		double precision, dimension(*)	x,
		integer	incx )

DTRMV

Purpose:

!>
!> DTRMV  performs one of the matrix-vector operations
!>
!>    x := A*x,   or   x := A**T*x,
!>
!> where x is an n element vector and  A is an n by n unit, or non-unit,
!> upper or lower triangular matrix.
!> 

Parameters

[in]	UPLO	!> UPLO is 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. !>
[in]	TRANS	!> TRANS is 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**T*x. !> !> TRANS = 'C' or 'c' x := A**T*x. !>
[in]	DIAG	!> DIAG is 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. !>
[in]	N	!> N is INTEGER !> On entry, N specifies the order of the matrix A. !> N must be at least zero. !>
[in]	A	!> A is DOUBLE PRECISION array, 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 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 matrix and the strictly upper triangular part of !> A is not referenced. !> Note that when DIAG = 'U' or 'u', the diagonal elements of !> A are not referenced either, but are assumed to be unity. !>
[in]	LDA	!> LDA is 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 ). !>
[in,out]	X	!> X is DOUBLE PRECISION array, 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 !> transformed vector x. !>
[in]	INCX	!> INCX is INTEGER !> On entry, INCX specifies the increment for the elements of !> X. INCX must not be zero. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:

!>
!>  Level 2 Blas routine.
!>  The vector and matrix arguments are not referenced when N = 0, or M = 0
!>
!>  -- 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.
!>