1DGTSV(1)                 LAPACK routine (version 3.1)                 DGTSV(1)
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NAME

6       DGTSV - the equation   A*X = B,
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SYNOPSIS

9       SUBROUTINE DGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )
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11           INTEGER       INFO, LDB, N, NRHS
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13           DOUBLE        PRECISION B( LDB, * ), D( * ), DL( * ), DU( * )
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PURPOSE

16       DGTSV  solves the equation
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18       where  A  is an n by n tridiagonal matrix, by Gaussian elimination with
19       partial pivoting.
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21       Note that the equation  A'*X = B  may be solved  by  interchanging  the
22       order of the arguments DU and DL.
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ARGUMENTS

26       N       (input) INTEGER
27               The order of the matrix A.  N >= 0.
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29       NRHS    (input) INTEGER
30               The  number of right hand sides, i.e., the number of columns of
31               the matrix B.  NRHS >= 0.
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33       DL      (input/output) DOUBLE PRECISION array, dimension (N-1)
34               On entry, DL must contain the (n-1) sub-diagonal elements of A.
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36               On exit, DL is overwritten by the (n-2) elements of the  second
37               super-diagonal  of  the  upper  triangular matrix U from the LU
38               factorization of A, in DL(1), ..., DL(n-2).
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40       D       (input/output) DOUBLE PRECISION array, dimension (N)
41               On entry, D must contain the diagonal elements of A.
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43               On exit, D is overwritten by the n diagonal elements of U.
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45       DU      (input/output) DOUBLE PRECISION array, dimension (N-1)
46               On entry, DU must contain the (n-1) super-diagonal elements  of
47               A.
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49               On  exit,  DU is overwritten by the (n-1) elements of the first
50               super-diagonal of U.
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52       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
53               On entry, the N by NRHS matrix of right hand side matrix B.  On
54               exit, if INFO = 0, the N by NRHS solution matrix X.
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56       LDB     (input) INTEGER
57               The leading dimension of the array B.  LDB >= max(1,N).
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59       INFO    (output) INTEGER
60               = 0: successful exit
61               < 0: if INFO = -i, the i-th argument had an illegal value
62               >  0: if INFO = i, U(i,i) is exactly zero, and the solution has
63               not been computed.  The factorization has  not  been  completed
64               unless i = N.
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68 LAPACK routine (version 3.1)    November 2006                        DGTSV(1)