dgttrs()

subroutine dgttrs	(	character	trans,
		integer	n,
		integer	nrhs,
		double precision, dimension( * )	dl,
		double precision, dimension( * )	d,
		double precision, dimension( * )	du,
		double precision, dimension( * )	du2,
		integer, dimension( * )	ipiv,
		double precision, dimension( ldb, * )	b,
		integer	ldb,
		integer	info )

DGTTRS

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Purpose:

!>
!> DGTTRS solves one of the systems of equations
!>    A*X = B  or  A**T*X = B,
!> with a tridiagonal matrix A using the LU factorization computed
!> by DGTTRF.
!> 

Parameters

[in]	TRANS	!> TRANS is CHARACTER*1 !> Specifies the form of the system of equations. !> = 'N': A * X = B (No transpose) !> = 'T': A**T* X = B (Transpose) !> = 'C': A**T* X = B (Conjugate transpose = Transpose) !>
[in]	N	!> N is INTEGER !> The order of the matrix A. !>
[in]	NRHS	!> NRHS is INTEGER !> The number of right hand sides, i.e., the number of columns !> of the matrix B. NRHS >= 0. !>
[in]	DL	!> DL is DOUBLE PRECISION array, dimension (N-1) !> The (n-1) multipliers that define the matrix L from the !> LU factorization of A. !>
[in]	D	!> D is DOUBLE PRECISION array, dimension (N) !> The n diagonal elements of the upper triangular matrix U from !> the LU factorization of A. !>
[in]	DU	!> DU is DOUBLE PRECISION array, dimension (N-1) !> The (n-1) elements of the first super-diagonal of U. !>
[in]	DU2	!> DU2 is DOUBLE PRECISION array, dimension (N-2) !> The (n-2) elements of the second super-diagonal of U. !>
[in]	IPIV	!> IPIV is INTEGER array, dimension (N) !> The pivot indices; for 1 <= i <= n, row i of the matrix was !> interchanged with row IPIV(i). IPIV(i) will always be either !> i or i+1; IPIV(i) = i indicates a row interchange was not !> required. !>
[in,out]	B	!> B is DOUBLE PRECISION array, dimension (LDB,NRHS) !> On entry, the matrix of right hand side vectors B. !> On exit, B is overwritten by the solution vectors X. !>
[in]	LDB	!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,N). !>
[out]	INFO	!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.