# dgtts2.f(3) [centos man page]

dgtts2.f(3) LAPACK dgtts2.f(3)NAME

dgtts2.f-SYNOPSIS

Functions/Subroutines subroutine dgtts2 (ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB) DGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf.Function/Subroutine Documentation subroutine dgtts2 (integerITRANS, integerN, integerNRHS, double precision, dimension( * )DL, double precision, dimension( * )D, double precision, dimension( * )DU, double precision, dimension( * )DU2, integer, dimension( * )IPIV, double precision, dimension( ldb, * )B, integerLDB) DGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf. Purpose: DGTTS2 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: ITRANS ITRANS is INTEGER Specifies the form of the system of equations. = 0: A * X = B (No transpose) = 1: A**T* X = B (Transpose) = 2: A**T* X = B (Conjugate transpose = Transpose) N N is INTEGER The order of the matrix A. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL DL is DOUBLE PRECISION array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D D is DOUBLE PRECISION array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU DU is DOUBLE PRECISION array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 DU2 is DOUBLE PRECISION array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. 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. 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. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Definition at line 129 of file dgtts2.f.AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 dgtts2.f(3)

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DGTTS2(l)) DGTTS2(l)NAME

DGTTS2 - solve one of the systems of equations A*X = B or A'*X = B,SYNOPSIS

SUBROUTINE DGTTS2( ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB ) INTEGER ITRANS, LDB, N, NRHS INTEGER IPIV( * ) DOUBLE PRECISION B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )PURPOSE

DGTTS2 solves one of the systems of equations A*X = B or A'*X = B, with a tridiagonal matrix A using the LU factorization computed by DGT- TRF.ARGUMENTS

ITRANS (input) INTEGER Specifies the form of the system of equations. = 0: A * X = B (No transpose) = 1: A'* X = B (Transpose) = 2: A'* X = B (Conjugate transpose = Transpose) N (input) INTEGER The order of the matrix A. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL (input) DOUBLE PRECISION array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D (input) DOUBLE PRECISION array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU (input) DOUBLE PRECISION array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 (input) DOUBLE PRECISION array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. IPIV (input) 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. B (input/output) 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. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N).LAPACK version 3.015 June 2000 DGTTS2(l)