LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
sgttrs.f File Reference

Go to the source code of this file.

Functions/Subroutines

subroutine SGTTRS (TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO)
 SGTTRS

Function/Subroutine Documentation

subroutine SGTTRS ( CHARACTER  TRANS,
INTEGER  N,
INTEGER  NRHS,
REAL, dimension( * )  DL,
REAL, dimension( * )  D,
REAL, dimension( * )  DU,
REAL, dimension( * )  DU2,
INTEGER, dimension( * )  IPIV,
REAL, dimension( ldb, * )  B,
INTEGER  LDB,
INTEGER  INFO 
)

SGTTRS

Download SGTTRS + dependencies [TGZ] [ZIP] [TXT]
Purpose:

 SGTTRS solves one of the systems of equations
    A*X = B  or  A**T*X = B,
 with a tridiagonal matrix A using the LU factorization computed
 by SGTTRF.
 
Parameters:
[in]TRANS
          TRANS is CHARACTER*1
          Specifies the form of the system of equations.
          = 'N':  A * X = B  (No transpose)
          = 'T':  A**T* X = B  (Transpose)
          = 'C':  A**T* X = B  (Conjugate transpose = Transpose)
 
[in]N
          N is INTEGER
          The order of the matrix A.
 
[in]NRHS
          NRHS is INTEGER
          The number of right hand sides, i.e., the number of columns
          of the matrix B.  NRHS >= 0.
 
[in]DL
          DL is REAL array, dimension (N-1)
          The (n-1) multipliers that define the matrix L from the
          LU factorization of A.
 
[in]D
          D is REAL array, dimension (N)
          The n diagonal elements of the upper triangular matrix U from
          the LU factorization of A.
 
[in]DU
          DU is REAL array, dimension (N-1)
          The (n-1) elements of the first super-diagonal of U.
 
[in]DU2
          DU2 is REAL array, dimension (N-2)
          The (n-2) elements of the second super-diagonal of U.
 
[in]IPIV
          IPIV is 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.
 
[in,out]B
          B is 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.
 
[in]LDB
          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).
 
[out]INFO
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
 
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011

Definition at line 138 of file sgttrs.f.

Here is the call graph for this function:

 All Files Functions