
SGTTS2(l) ) SGTTS2(l)
NAME
SGTTS2  solve one of the systems of equations A*X = B or A'*X = B,
SYNOPSIS
SUBROUTINE SGTTS2( ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB )
INTEGER ITRANS, LDB, N, NRHS
INTEGER IPIV( * )
REAL B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
PURPOSE
SGTTS2 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 SGTTRF.
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) REAL array, dimension (N1)
The (n1) multipliers that define the matrix L from the LU factorization of A.
D (input) REAL array, dimension (N)
The n diagonal elements of the upper triangular matrix U from the LU factorization
of A.
DU (input) REAL array, dimension (N1)
The (n1) elements of the first superdiagonal of U.
DU2 (input) REAL array, dimension (N2)
The (n2) elements of the second superdiagonal 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) REAL 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 3.0 15 June 2000 SGTTS2(l) 
