NAME

       sgtsv.f -

SYNOPSIS

   Functions/Subroutines
       subroutine sgtsv (N, NRHS, DL, D, DU, B, LDB, INFO)
            SGTSV computes the solution to system of linear equations A * X = B for GT matrices

Function/Subroutine Documentation

   subroutine sgtsv (integerN, integerNRHS, real, dimension( * )DL, real, dimension( * )D, real,
       dimension( * )DU, real, dimension( ldb, * )B, integerLDB, integerINFO)
        SGTSV computes the solution to system of linear equations A * X = B for GT matrices

       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:
           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           NRHS

                     NRHS is INTEGER
                     The number of right hand sides, i.e., the number of columns
                     of the matrix B.  NRHS >= 0.

           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).

           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.

           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.

           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.

           LDB

                     LDB is INTEGER
                     The leading dimension of the array B.  LDB >= max(1,N).

           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:
           September 2012

       Definition at line 128 of file sgtsv.f.

Author

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