1SGTTRS(1)                LAPACK routine (version 3.2)                SGTTRS(1)
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NAME

6       SGTTRS - solves one of the systems of equations  A*X = B or A'*X = B,
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SYNOPSIS

9       SUBROUTINE SGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
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11           CHARACTER      TRANS
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13           INTEGER        INFO, LDB, N, NRHS
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15           INTEGER        IPIV( * )
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17           REAL           B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
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PURPOSE

20       SGTTRS solves one of the systems of equations
21          A*X = B  or  A'*X = B, with a tridiagonal matrix A using the LU fac‐
22       torization computed by SGTTRF.
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ARGUMENTS

25       TRANS   (input) CHARACTER*1
26               Specifies the form of the system of equations.  = 'N':  A * X =
27               B  (No transpose)
28               = 'T':  A'* X = B  (Transpose)
29               = 'C':  A'* X = B  (Conjugate transpose = Transpose)
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31       N       (input) INTEGER
32               The order of the matrix A.
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34       NRHS    (input) INTEGER
35               The  number of right hand sides, i.e., the number of columns of
36               the matrix B.  NRHS >= 0.
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38       DL      (input) REAL array, dimension (N-1)
39               The (n-1) multipliers that define the matrix L from the LU fac‐
40               torization of A.
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42       D       (input) REAL array, dimension (N)
43               The  n  diagonal elements of the upper triangular matrix U from
44               the LU factorization of A.
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46       DU      (input) REAL array, dimension (N-1)
47               The (n-1) elements of the first super-diagonal of U.
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49       DU2     (input) REAL array, dimension (N-2)
50               The (n-2) elements of the second super-diagonal of U.
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52       IPIV    (input) INTEGER array, dimension (N)
53               The pivot indices; for 1 <= i <= n, row i  of  the  matrix  was
54               interchanged with row IPIV(i).  IPIV(i) will always be either i
55               or i+1; IPIV(i)  =  i  indicates  a  row  interchange  was  not
56               required.
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58       B       (input/output) REAL array, dimension (LDB,NRHS)
59               On  entry, the matrix of right hand side vectors B.  On exit, B
60               is overwritten by the solution vectors X.
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62       LDB     (input) INTEGER
63               The leading dimension of the array B.  LDB >= max(1,N).
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65       INFO    (output) INTEGER
66               = 0:  successful exit
67               < 0:  if INFO = -i, the i-th argument had an illegal value
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71 LAPACK routine (version 3.2)    November 2008                       SGTTRS(1)
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