1SGTTS2(1)           LAPACK auxiliary routine (version 3.1)           SGTTS2(1)
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NAME

6       SGTTS2 - 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

24       ITRANS  (input) INTEGER
25               Specifies the form of the system of equations.  = 0:  A * X = B
26               (No transpose)
27               = 1:  A'* X = B  (Transpose)
28               = 2:  A'* X = B  (Conjugate transpose = Transpose)
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30       N       (input) INTEGER
31               The order of the matrix A.
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33       NRHS    (input) INTEGER
34               The  number of right hand sides, i.e., the number of columns of
35               the matrix B.  NRHS >= 0.
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37       DL      (input) REAL array, dimension (N-1)
38               The (n-1) multipliers that define the matrix L from the LU fac‐
39               torization of A.
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41       D       (input) REAL array, dimension (N)
42               The  n  diagonal elements of the upper triangular matrix U from
43               the LU factorization of A.
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45       DU      (input) REAL array, dimension (N-1)
46               The (n-1) elements of the first super-diagonal of U.
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48       DU2     (input) REAL array, dimension (N-2)
49               The (n-2) elements of the second super-diagonal of U.
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51       IPIV    (input) INTEGER array, dimension (N)
52               The pivot indices; for 1 <= i <= n, row i  of  the  matrix  was
53               interchanged with row IPIV(i).  IPIV(i) will always be either i
54               or i+1; IPIV(i)  =  i  indicates  a  row  interchange  was  not
55               required.
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57       B       (input/output) REAL array, dimension (LDB,NRHS)
58               On  entry, the matrix of right hand side vectors B.  On exit, B
59               is overwritten by the solution vectors X.
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61       LDB     (input) INTEGER
62               The leading dimension of the array B.  LDB >= max(1,N).
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66 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       SGTTS2(1)
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