SGTTS2(1) LAPACK auxiliary routine (version 3.2) SGTTS2(1)NAME
SGTTS2 - solves 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 fac‐
torization 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 (N-1)
The (n-1) multipliers that define the matrix L from the LU fac‐
torization 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 (N-1)
The (n-1) elements of the first super-diagonal of U.
DU2 (input) REAL 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) 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 auxiliary routine (versioNovember 2008 SGTTS2(1)
