1CGTTRS(1) LAPACK routine (version 3.2) CGTTRS(1)
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6 CGTTRS - solves one of the systems of equations A * X = B, A**T * X =
7 B, or A**H * X = B,
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10 SUBROUTINE CGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
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12 CHARACTER TRANS
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14 INTEGER INFO, LDB, N, NRHS
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16 INTEGER IPIV( * )
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18 COMPLEX B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
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21 CGTTRS solves one of the systems of equations
22 A * X = B, A**T * X = B, or A**H * X = B, with a tridiagonal
23 matrix A using the LU factorization computed by CGTTRF.
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26 TRANS (input) CHARACTER*1
27 Specifies the form of the system of equations. = 'N': A * X =
28 B (No transpose)
29 = 'T': A**T * X = B (Transpose)
30 = 'C': A**H * X = B (Conjugate transpose)
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32 N (input) INTEGER
33 The order of the matrix A.
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35 NRHS (input) INTEGER
36 The number of right hand sides, i.e., the number of columns of
37 the matrix B. NRHS >= 0.
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39 DL (input) COMPLEX array, dimension (N-1)
40 The (n-1) multipliers that define the matrix L from the LU fac‐
41 torization of A.
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43 D (input) COMPLEX array, dimension (N)
44 The n diagonal elements of the upper triangular matrix U from
45 the LU factorization of A.
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47 DU (input) COMPLEX array, dimension (N-1)
48 The (n-1) elements of the first super-diagonal of U.
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50 DU2 (input) COMPLEX array, dimension (N-2)
51 The (n-2) elements of the second super-diagonal of U.
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53 IPIV (input) INTEGER array, dimension (N)
54 The pivot indices; for 1 <= i <= n, row i of the matrix was
55 interchanged with row IPIV(i). IPIV(i) will always be either i
56 or i+1; IPIV(i) = i indicates a row interchange was not
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59 B (input/output) COMPLEX array, dimension (LDB,NRHS)
60 On entry, the matrix of right hand side vectors B. On exit, B
61 is overwritten by the solution vectors X.
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63 LDB (input) INTEGER
64 The leading dimension of the array B. LDB >= max(1,N).
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66 INFO (output) INTEGER
67 = 0: successful exit
68 < 0: if INFO = -k, the k-th argument had an illegal value
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72 LAPACK routine (version 3.2) November 2008 CGTTRS(1)