Annotation of rpl/lapack/lapack/zptsv.f, revision 1.19
1.12 bertrand 1: *> \brief <b> ZPTSV computes the solution to system of linear equations A * X = B for PT matrices</b>
1.9 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
1.16 bertrand 5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
1.9 bertrand 7: *
8: *> \htmlonly
1.16 bertrand 9: *> Download ZPTSV + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zptsv.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zptsv.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zptsv.f">
1.9 bertrand 15: *> [TXT]</a>
1.16 bertrand 16: *> \endhtmlonly
1.9 bertrand 17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZPTSV( N, NRHS, D, E, B, LDB, INFO )
1.16 bertrand 22: *
1.9 bertrand 23: * .. Scalar Arguments ..
24: * INTEGER INFO, LDB, N, NRHS
25: * ..
26: * .. Array Arguments ..
27: * DOUBLE PRECISION D( * )
28: * COMPLEX*16 B( LDB, * ), E( * )
29: * ..
1.16 bertrand 30: *
1.9 bertrand 31: *
32: *> \par Purpose:
33: * =============
34: *>
35: *> \verbatim
36: *>
37: *> ZPTSV computes the solution to a complex system of linear equations
38: *> A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal
39: *> matrix, and X and B are N-by-NRHS matrices.
40: *>
41: *> A is factored as A = L*D*L**H, and the factored form of A is then
42: *> used to solve the system of equations.
43: *> \endverbatim
44: *
45: * Arguments:
46: * ==========
47: *
48: *> \param[in] N
49: *> \verbatim
50: *> N is INTEGER
51: *> The order of the matrix A. N >= 0.
52: *> \endverbatim
53: *>
54: *> \param[in] NRHS
55: *> \verbatim
56: *> NRHS is INTEGER
57: *> The number of right hand sides, i.e., the number of columns
58: *> of the matrix B. NRHS >= 0.
59: *> \endverbatim
60: *>
61: *> \param[in,out] D
62: *> \verbatim
63: *> D is DOUBLE PRECISION array, dimension (N)
64: *> On entry, the n diagonal elements of the tridiagonal matrix
65: *> A. On exit, the n diagonal elements of the diagonal matrix
66: *> D from the factorization A = L*D*L**H.
67: *> \endverbatim
68: *>
69: *> \param[in,out] E
70: *> \verbatim
71: *> E is COMPLEX*16 array, dimension (N-1)
72: *> On entry, the (n-1) subdiagonal elements of the tridiagonal
73: *> matrix A. On exit, the (n-1) subdiagonal elements of the
74: *> unit bidiagonal factor L from the L*D*L**H factorization of
75: *> A. E can also be regarded as the superdiagonal of the unit
76: *> bidiagonal factor U from the U**H*D*U factorization of A.
77: *> \endverbatim
78: *>
79: *> \param[in,out] B
80: *> \verbatim
81: *> B is COMPLEX*16 array, dimension (LDB,NRHS)
82: *> On entry, the N-by-NRHS right hand side matrix B.
83: *> On exit, if INFO = 0, the N-by-NRHS solution matrix X.
84: *> \endverbatim
85: *>
86: *> \param[in] LDB
87: *> \verbatim
88: *> LDB is INTEGER
89: *> The leading dimension of the array B. LDB >= max(1,N).
90: *> \endverbatim
91: *>
92: *> \param[out] INFO
93: *> \verbatim
94: *> INFO is INTEGER
95: *> = 0: successful exit
96: *> < 0: if INFO = -i, the i-th argument had an illegal value
97: *> > 0: if INFO = i, the leading minor of order i is not
98: *> positive definite, and the solution has not been
99: *> computed. The factorization has not been completed
100: *> unless i = N.
101: *> \endverbatim
102: *
103: * Authors:
104: * ========
105: *
1.16 bertrand 106: *> \author Univ. of Tennessee
107: *> \author Univ. of California Berkeley
108: *> \author Univ. of Colorado Denver
109: *> \author NAG Ltd.
1.9 bertrand 110: *
1.12 bertrand 111: *> \ingroup complex16PTsolve
1.9 bertrand 112: *
113: * =====================================================================
1.1 bertrand 114: SUBROUTINE ZPTSV( N, NRHS, D, E, B, LDB, INFO )
115: *
1.19 ! bertrand 116: * -- LAPACK driver routine --
1.1 bertrand 117: * -- LAPACK is a software package provided by Univ. of Tennessee, --
118: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
119: *
120: * .. Scalar Arguments ..
121: INTEGER INFO, LDB, N, NRHS
122: * ..
123: * .. Array Arguments ..
124: DOUBLE PRECISION D( * )
125: COMPLEX*16 B( LDB, * ), E( * )
126: * ..
127: *
128: * =====================================================================
129: *
130: * .. External Subroutines ..
131: EXTERNAL XERBLA, ZPTTRF, ZPTTRS
132: * ..
133: * .. Intrinsic Functions ..
134: INTRINSIC MAX
135: * ..
136: * .. Executable Statements ..
137: *
138: * Test the input parameters.
139: *
140: INFO = 0
141: IF( N.LT.0 ) THEN
142: INFO = -1
143: ELSE IF( NRHS.LT.0 ) THEN
144: INFO = -2
145: ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
146: INFO = -6
147: END IF
148: IF( INFO.NE.0 ) THEN
149: CALL XERBLA( 'ZPTSV ', -INFO )
150: RETURN
151: END IF
152: *
1.8 bertrand 153: * Compute the L*D*L**H (or U**H*D*U) factorization of A.
1.1 bertrand 154: *
155: CALL ZPTTRF( N, D, E, INFO )
156: IF( INFO.EQ.0 ) THEN
157: *
158: * Solve the system A*X = B, overwriting B with X.
159: *
160: CALL ZPTTRS( 'Lower', N, NRHS, D, E, B, LDB, INFO )
161: END IF
162: RETURN
163: *
164: * End of ZPTSV
165: *
166: END
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