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

6       CGTTRS  -  one of the systems of equations  A * X = B, A**T * X = B, or
7       A**H * X = B,
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SYNOPSIS

10       SUBROUTINE CGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
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12           CHARACTER      TRANS
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14           INTEGER        INFO, LDB, N, NRHS
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16           INTEGER        IPIV( * )
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18           COMPLEX        B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
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PURPOSE

21       CGTTRS solves one of the systems of equations
22          A * X = B,  A**T * X = B,  or  A**H * X  =  B,  with  a  tridiagonal
23       matrix A using the LU factorization computed by CGTTRF.
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ARGUMENTS

27       TRANS   (input) CHARACTER*1
28               Specifies the form of the system of equations.  = 'N':  A * X =
29               B     (No transpose)
30               = 'T':  A**T * X = B  (Transpose)
31               = 'C':  A**H * X = B  (Conjugate transpose)
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33       N       (input) INTEGER
34               The order of the matrix A.
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36       NRHS    (input) INTEGER
37               The number of right hand sides, i.e., the number of columns  of
38               the matrix B.  NRHS >= 0.
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40       DL      (input) COMPLEX array, dimension (N-1)
41               The (n-1) multipliers that define the matrix L from the LU fac‐
42               torization of A.
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44       D       (input) COMPLEX array, dimension (N)
45               The n diagonal elements of the upper triangular matrix  U  from
46               the LU factorization of A.
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48       DU      (input) COMPLEX array, dimension (N-1)
49               The (n-1) elements of the first super-diagonal of U.
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51       DU2     (input) COMPLEX array, dimension (N-2)
52               The (n-2) elements of the second super-diagonal of U.
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54       IPIV    (input) INTEGER array, dimension (N)
55               The  pivot  indices;  for  1 <= i <= n, row i of the matrix was
56               interchanged with row IPIV(i).  IPIV(i) will always be either i
57               or  i+1;  IPIV(i)  =  i  indicates  a  row  interchange was not
58               required.
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60       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
61               On entry, the matrix of right hand side vectors B.  On exit,  B
62               is overwritten by the solution vectors X.
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64       LDB     (input) INTEGER
65               The leading dimension of the array B.  LDB >= max(1,N).
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67       INFO    (output) INTEGER
68               = 0:  successful exit
69               < 0:  if INFO = -k, the k-th argument had an illegal value
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73 LAPACK routine (version 3.1)    November 2006                       CGTTRS(1)
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