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

6       ZTBTRS  - a triangular system of the form   A * X = B, A**T * X = B, or
7       A**H * X = B,
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SYNOPSIS

10       SUBROUTINE ZTBTRS( UPLO, TRANS, DIAG, N, KD, NRHS, AB,  LDAB,  B,  LDB,
11                          INFO )
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13           CHARACTER      DIAG, TRANS, UPLO
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15           INTEGER        INFO, KD, LDAB, LDB, N, NRHS
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17           COMPLEX*16     AB( LDAB, * ), B( LDB, * )
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PURPOSE

20       ZTBTRS solves a triangular system of the form
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22       where  A  is a triangular band matrix of order N, and B is an N-by-NRHS
23       matrix.  A check is made to verify that A is nonsingular.
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ARGUMENTS

27       UPLO    (input) CHARACTER*1
28               = 'U':  A is upper triangular;
29               = 'L':  A is lower triangular.
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31       TRANS   (input) CHARACTER*1
32               Specifies the form of the system of equations:
33               = 'N':  A * X = B     (No transpose)
34               = 'T':  A**T * X = B  (Transpose)
35               = 'C':  A**H * X = B  (Conjugate transpose)
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37       DIAG    (input) CHARACTER*1
38               = 'N':  A is non-unit triangular;
39               = 'U':  A is unit triangular.
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41       N       (input) INTEGER
42               The order of the matrix A.  N >= 0.
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44       KD      (input) INTEGER
45               The number of superdiagonals or subdiagonals of the  triangular
46               band matrix A.  KD >= 0.
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48       NRHS    (input) INTEGER
49               The  number of right hand sides, i.e., the number of columns of
50               the matrix B.  NRHS >= 0.
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52       AB      (input) COMPLEX*16 array, dimension (LDAB,N)
53               The upper or lower triangular band  matrix  A,  stored  in  the
54               first  kd+1  rows of AB.  The j-th column of A is stored in the
55               j-th column of  the  array  AB  as  follows:  if  UPLO  =  'U',
56               AB(kd+1+i-j,j)  =  A(i,j) for max(1,j-kd)<=i<=j; if UPLO = 'L',
57               AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).  If DIAG =  'U',
58               the  diagonal  elements of A are not referenced and are assumed
59               to be 1.
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61       LDAB    (input) INTEGER
62               The leading dimension of the array AB.  LDAB >= KD+1.
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64       B       (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
65               On entry, the right hand side matrix B.  On exit, if INFO =  0,
66               the solution matrix X.
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68       LDB     (input) INTEGER
69               The leading dimension of the array B.  LDB >= max(1,N).
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71       INFO    (output) INTEGER
72               = 0:  successful exit
73               < 0:  if INFO = -i, the i-th argument had an illegal value
74               >  0:   if  INFO  =  i, the i-th diagonal element of A is zero,
75               indicating that the matrix is singular and the solutions X have
76               not been computed.
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80 LAPACK routine (version 3.1)    November 2006                       ZTBTRS(1)
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