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sgtts2.f File Reference

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Functions/Subroutines

subroutine sgtts2 (ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB)
 SGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf. More...
 

Function/Subroutine Documentation

subroutine sgtts2 ( integer  ITRANS,
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 
)

SGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf.

Download SGTTS2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 SGTTS2 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]ITRANS
          ITRANS is INTEGER
          Specifies the form of the system of equations.
          = 0:  A * X = B  (No transpose)
          = 1:  A**T* X = B  (Transpose)
          = 2:  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).
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
September 2012

Definition at line 129 of file sgtts2.f.

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