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

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

9       SUBROUTINE CGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )
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11           INTEGER       INFO, LDB, N, NRHS
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13           COMPLEX       B( LDB, * ), D( * ), DL( * ), DU( * )
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PURPOSE

16       CGTSV  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) COMPLEX array, dimension (N-1)
34               On entry, DL must contain the (n-1) subdiagonal elements of  A.
35               On  exit, DL is overwritten by the (n-2) elements of the second
36               superdiagonal of the upper triangular matrix U from the LU fac‐
37               torization of A, in DL(1), ..., DL(n-2).
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39       D       (input/output) COMPLEX array, dimension (N)
40               On  entry, D must contain the diagonal elements of A.  On exit,
41               D is overwritten by the n diagonal elements of U.
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43       DU      (input/output) COMPLEX array, dimension (N-1)
44               On entry, DU must contain the (n-1) superdiagonal  elements  of
45               A.   On  exit,  DU  is overwritten by the (n-1) elements of the
46               first superdiagonal of U.
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48       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
49               On entry, the N-by-NRHS right hand side matrix B.  On exit,  if
50               INFO = 0, the N-by-NRHS solution matrix X.
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52       LDB     (input) INTEGER
53               The leading dimension of the array B.  LDB >= max(1,N).
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55       INFO    (output) INTEGER
56               = 0:  successful exit
57               < 0:  if INFO = -i, the i-th argument had an illegal value
58               > 0:  if INFO = i, U(i,i) is exactly zero, and the solution has
59               not been computed.  The factorization has  not  been  completed
60               unless i = N.
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64 LAPACK routine (version 3.1)    November 2006                        CGTSV(1)