sgttrs (l)  Linux Manuals
sgttrs: solves one of the systems of equations A*X = B or Aaq*X = B,
NAME
SGTTRS  solves one of the systems of equations A*X = B or Aaq*X = B,SYNOPSIS
 SUBROUTINE SGTTRS(
 TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
 CHARACTER TRANS
 INTEGER INFO, LDB, N, NRHS
 INTEGER IPIV( * )
 REAL B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
PURPOSE
SGTTRS solves one of the systems of equationsA*X
ARGUMENTS
 TRANS (input) CHARACTER*1

Specifies the form of the system of equations.
= aqNaq: A * X = B (No transpose)
= aqTaq: Aaq* X = B (Transpose)
= aqCaq: Aaq* 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 (N1)
 The (n1) multipliers that define the matrix L from the LU factorization 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 (N1)
 The (n1) elements of the first superdiagonal of U.
 DU2 (input) REAL array, dimension (N2)
 The (n2) elements of the second superdiagonal 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).
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value