Provided by: liblapack-doc_3.3.1-1_all

**NAME**

LAPACK-3 - solves one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B,

**SYNOPSIS**

SUBROUTINE ZGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO ) CHARACTER TRANS INTEGER INFO, LDB, N, NRHS INTEGER IPIV( * ) COMPLEX*16 B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )

**PURPOSE**

ZGTTRS 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 ZGTTRF.

**ARGUMENTS**

TRANS (input) CHARACTER*1 Specifies the form of the system of equations. = 'N': A * X = B (No transpose) = '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 >= 0. DL (input) COMPLEX*16 array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D (input) COMPLEX*16 array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU (input) COMPLEX*16 array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 (input) COMPLEX*16 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*16 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 routine (version 3.2) April 2011 ZGTTRS(3lapack)