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

6       ZPTTRS  - a tridiagonal system of the form  A * X = B using the factor‐
7       ization A = U'*D*U or A = L*D*L' computed by ZPTTRF
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SYNOPSIS

10       SUBROUTINE ZPTTRS( UPLO, N, NRHS, D, E, B, LDB, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, LDB, N, NRHS
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16           DOUBLE         PRECISION D( * )
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18           COMPLEX*16     B( LDB, * ), E( * )
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PURPOSE

21       ZPTTRS solves a tridiagonal system of the form
22          A * X = B using the factorization A = U'*D*U or A = L*D*L'  computed
23       by  ZPTTRF.  D is a diagonal matrix specified in the vector D, U (or L)
24       is a unit bidiagonal matrix whose superdiagonal (subdiagonal) is speci‐
25       fied in the vector E, and X and B are N by NRHS matrices.
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ARGUMENTS

29       UPLO    (input) CHARACTER*1
30               Specifies  the form of the factorization and whether the vector
31               E is the superdiagonal of the upper bidiagonal factor U or  the
32               subdiagonal  of  the  lower  bidiagonal  factor L.  = 'U':  A =
33               U'*D*U, E is the superdiagonal of U
34               = 'L':  A = L*D*L', E is the subdiagonal of L
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36       N       (input) INTEGER
37               The order of the tridiagonal matrix A.  N >= 0.
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39       NRHS    (input) INTEGER
40               The number of right hand sides, i.e., the number of columns  of
41               the matrix B.  NRHS >= 0.
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43       D       (input) DOUBLE PRECISION array, dimension (N)
44               The  n diagonal elements of the diagonal matrix D from the fac‐
45               torization A = U'*D*U or A = L*D*L'.
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47       E       (input) COMPLEX*16 array, dimension (N-1)
48               If UPLO = 'U', the (n-1) superdiagonal  elements  of  the  unit
49               bidiagonal factor U from the factorization A = U'*D*U.  If UPLO
50               = 'L', the (n-1) subdiagonal elements of  the  unit  bidiagonal
51               factor L from the factorization A = L*D*L'.
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53       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
54               On  entry, the right hand side vectors B for the system of lin‐
55               ear equations.  On exit, the solution vectors, X.
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57       LDB     (input) INTEGER
58               The leading dimension of the array B.  LDB >= max(1,N).
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60       INFO    (output) INTEGER
61               = 0: successful exit
62               < 0: if INFO = -k, the k-th argument had an illegal value
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66 LAPACK routine (version 3.1)    November 2006                       ZPTTRS(1)
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