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

6       SPTTRS  -  a tridiagonal system of the form  A * X = B using the L*D*L'
7       factorization of A computed by SPTTRF
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SYNOPSIS

10       SUBROUTINE SPTTRS( N, NRHS, D, E, B, LDB, INFO )
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12           INTEGER        INFO, LDB, N, NRHS
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14           REAL           B( LDB, * ), D( * ), E( * )
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PURPOSE

17       SPTTRS solves a tridiagonal system of the form
18          A * X = B using the L*D*L' factorization of A computed by SPTTRF.  D
19       is  a diagonal matrix specified in the vector D, L is a unit bidiagonal
20       matrix whose subdiagonal is specified in the vector E, and X and B  are
21       N by NRHS matrices.
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ARGUMENTS

25       N       (input) INTEGER
26               The order of the tridiagonal matrix A.  N >= 0.
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28       NRHS    (input) INTEGER
29               The  number of right hand sides, i.e., the number of columns of
30               the matrix B.  NRHS >= 0.
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32       D       (input) REAL array, dimension (N)
33               The n diagonal elements of  the  diagonal  matrix  D  from  the
34               L*D*L' factorization of A.
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36       E       (input) REAL array, dimension (N-1)
37               The  (n-1) subdiagonal elements of the unit bidiagonal factor L
38               from the L*D*L' factorization of A.  E can also be regarded  as
39               the superdiagonal of the unit bidiagonal factor U from the fac‐
40               torization A = U'*D*U.
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42       B       (input/output) REAL array, dimension (LDB,NRHS)
43               On entry, the right hand side vectors B for the system of  lin‐
44               ear equations.  On exit, the solution vectors, X.
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46       LDB     (input) INTEGER
47               The leading dimension of the array B.  LDB >= max(1,N).
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49       INFO    (output) INTEGER
50               = 0: successful exit
51               < 0: if INFO = -k, the k-th argument had an illegal value
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55 LAPACK routine (version 3.1)    November 2006                       SPTTRS(1)
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