.TH ZTRTRS 1 "November 2006" " LAPACK routine (version 3.1) " " LAPACK routine (version 3.1) " .SH NAME ZTRTRS - a triangular system of the form A * X = B, A**T * X = B, or A**H * X = B, .SH SYNOPSIS .TP 19 SUBROUTINE ZTRTRS( UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB, INFO ) .TP 19 .ti +4 CHARACTER DIAG, TRANS, UPLO .TP 19 .ti +4 INTEGER INFO, LDA, LDB, N, NRHS .TP 19 .ti +4 COMPLEX*16 A( LDA, * ), B( LDB, * ) .SH PURPOSE ZTRTRS solves a triangular system of the form where A is a triangular matrix of order N, and B is an N-by-NRHS matrix. A check is made to verify that A is nonsingular. .SH ARGUMENTS .TP 8 UPLO (input) CHARACTER*1 = \(aqU\(aq: A is upper triangular; .br = \(aqL\(aq: A is lower triangular. .TP 8 TRANS (input) CHARACTER*1 .br Specifies the form of the system of equations: .br = \(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 DIAG (input) CHARACTER*1 .br = \(aqN\(aq: A is non-unit triangular; .br = \(aqU\(aq: A is unit triangular. .TP 8 N (input) INTEGER The order of the matrix A. N >= 0. .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 A (input) COMPLEX*16 array, dimension (LDA,N) The triangular matrix A. If UPLO = \(aqU\(aq, the leading N-by-N upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = \(aqL\(aq, the leading N-by-N lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced. If DIAG = \(aqU\(aq, the diagonal elements of A are also not referenced and are assumed to be 1. .TP 8 LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). .TP 8 B (input/output) COMPLEX*16 array, dimension (LDB,NRHS) On entry, the right hand side matrix B. On exit, if INFO = 0, the solution matrix 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 = -i, the i-th argument had an illegal value .br > 0: if INFO = i, the i-th diagonal element of A is zero, indicating that the matrix is singular and the solutions X have not been computed.