CGTTRS(l) ) CGTTRS(l)
CGTTRS - solve one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B,
SUBROUTINE CGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
INTEGER INFO, LDB, N, NRHS
INTEGER IPIV( * )
COMPLEX B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
CGTTRS solves one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B,
with a tridiagonal matrix A using the LU factorization computed by CGTTRF.
TRANS (input) CHARACTER
Specifies the form of the system of equations. = 'N': A * X = B (No trans-
= 'T': A**T * X = B (Transpose)
= 'C': A**H * X = B (Conjugate 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
DL (input) COMPLEX array, dimension (N-1)
The (n-1) multipliers that define the matrix L from the LU factorization of A.
D (input) COMPLEX array, dimension (N)
The n diagonal elements of the upper triangular matrix U from the LU factorization
DU (input) COMPLEX array, dimension (N-1)
The (n-1) elements of the first super-diagonal of U.
DU2 (input) COMPLEX 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) COMPLEX 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).
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
LAPACK version 3.0 15 June 2000 CGTTRS(l)