LAPACK  3.4.0
LAPACK: Linear Algebra PACKage
Functions/Subroutines
sgtsv.f File Reference

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Functions/Subroutines

subroutine SGTSV (N, NRHS, DL, D, DU, B, LDB, INFO)
 SGTSV

Function/Subroutine Documentation

subroutine SGTSV ( INTEGER  N,
INTEGER  NRHS,
REAL, dimension( * )  DL,
REAL, dimension( * )  D,
REAL, dimension( * )  DU,
REAL, dimension( ldb, * )  B,
INTEGER  LDB,
INTEGER  INFO 
)

SGTSV

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

 SGTSV  solves the equation

    A*X = B,

 where A is an n by n tridiagonal matrix, by Gaussian elimination with
 partial pivoting.

 Note that the equation  A**T*X = B  may be solved by interchanging the
 order of the arguments DU and DL.
Parameters:
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in]NRHS
          NRHS is INTEGER
          The number of right hand sides, i.e., the number of columns
          of the matrix B.  NRHS >= 0.
[in,out]DL
          DL is REAL array, dimension (N-1)
          On entry, DL must contain the (n-1) sub-diagonal elements of
          A.

          On exit, DL is overwritten by the (n-2) elements of the
          second super-diagonal of the upper triangular matrix U from
          the LU factorization of A, in DL(1), ..., DL(n-2).
[in,out]D
          D is REAL array, dimension (N)
          On entry, D must contain the diagonal elements of A.

          On exit, D is overwritten by the n diagonal elements of U.
[in,out]DU
          DU is REAL array, dimension (N-1)
          On entry, DU must contain the (n-1) super-diagonal elements
          of A.

          On exit, DU is overwritten by the (n-1) elements of the first
          super-diagonal of U.
[in,out]B
          B is REAL array, dimension (LDB,NRHS)
          On entry, the N by NRHS matrix of right hand side matrix B.
          On exit, if INFO = 0, the N by NRHS solution matrix 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
          > 0: if INFO = i, U(i,i) is exactly zero, and the solution
               has not been computed.  The factorization has not been
               completed unless i = N.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011

Definition at line 128 of file sgtsv.f.

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