.TH CGTTRS 1 "November 2006" " LAPACK routine (version 3.1) " " LAPACK routine (version 3.1) " .SH NAME CGTTRS - one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B, .SH SYNOPSIS .TP 19 SUBROUTINE CGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO ) .TP 19 .ti +4 CHARACTER TRANS .TP 19 .ti +4 INTEGER INFO, LDB, N, NRHS .TP 19 .ti +4 INTEGER IPIV( * ) .TP 19 .ti +4 COMPLEX B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * ) .SH PURPOSE 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. .br .SH ARGUMENTS .TP 8 TRANS (input) CHARACTER*1 Specifies the form of the system of equations. = \(aqN\(aq: A * X = B (No transpose) .br = \(aqT\(aq: A**T * X = B (Transpose) .br = \(aqC\(aq: A**H * X = B (Conjugate transpose) .TP 8 N (input) INTEGER The order of the matrix A. .TP 8 NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. .TP 8 DL (input) COMPLEX array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. .TP 8 D (input) COMPLEX array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. .TP 8 DU (input) COMPLEX array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. .TP 8 DU2 (input) COMPLEX array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. .TP 8 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. .TP 8 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. .TP 8 LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). .TP 8 INFO (output) INTEGER = 0: successful exit .br < 0: if INFO = -k, the k-th argument had an illegal value