1SGTTS2(1)           LAPACK auxiliary routine (version 3.2)           SGTTS2(1)
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NAME

6       SGTTS2 - solves one of the systems of equations  A*X = B or A'*X = B,
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SYNOPSIS

9       SUBROUTINE SGTTS2( ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB )
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11           INTEGER        ITRANS, LDB, N, NRHS
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13           INTEGER        IPIV( * )
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15           REAL           B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
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PURPOSE

18       SGTTS2 solves one of the systems of equations
19          A*X = B  or  A'*X = B, with a tridiagonal matrix A using the LU fac‐
20       torization computed by SGTTRF.
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ARGUMENTS

23       ITRANS  (input) INTEGER
24               Specifies the form of the system of equations.  = 0:  A * X = B
25               (No transpose)
26               = 1:  A'* X = B  (Transpose)
27               = 2:  A'* X = B  (Conjugate transpose = Transpose)
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29       N       (input) INTEGER
30               The order of the matrix A.
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32       NRHS    (input) INTEGER
33               The  number of right hand sides, i.e., the number of columns of
34               the matrix B.  NRHS >= 0.
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36       DL      (input) REAL array, dimension (N-1)
37               The (n-1) multipliers that define the matrix L from the LU fac‐
38               torization of A.
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40       D       (input) REAL array, dimension (N)
41               The  n  diagonal elements of the upper triangular matrix U from
42               the LU factorization of A.
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44       DU      (input) REAL array, dimension (N-1)
45               The (n-1) elements of the first super-diagonal of U.
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47       DU2     (input) REAL array, dimension (N-2)
48               The (n-2) elements of the second super-diagonal of U.
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50       IPIV    (input) INTEGER array, dimension (N)
51               The pivot indices; for 1 <= i <= n, row i  of  the  matrix  was
52               interchanged with row IPIV(i).  IPIV(i) will always be either i
53               or i+1; IPIV(i)  =  i  indicates  a  row  interchange  was  not
54               required.
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56       B       (input/output) REAL array, dimension (LDB,NRHS)
57               On  entry, the matrix of right hand side vectors B.  On exit, B
58               is overwritten by the solution vectors X.
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60       LDB     (input) INTEGER
61               The leading dimension of the array B.  LDB >= max(1,N).
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65 LAPACK auxiliary routine (versionNo3v.e2m)ber 2008                       SGTTS2(1)
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