Annotation of rpl/lapack/lapack/zgesv.f, revision 1.14
1.14 ! bertrand 1: *> \brief <b> ZGESV computes the solution to system of linear equations A * X = B for GE matrices</b> (simple driver) </b>
1.8 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
1.14 ! bertrand 5: * Online html documentation available at
! 6: * http://www.netlib.org/lapack/explore-html/
1.8 bertrand 7: *
8: *> \htmlonly
1.14 ! bertrand 9: *> Download ZGESV + dependencies
! 10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zgesv.f">
! 11: *> [TGZ]</a>
! 12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zgesv.f">
! 13: *> [ZIP]</a>
! 14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zgesv.f">
1.8 bertrand 15: *> [TXT]</a>
1.14 ! bertrand 16: *> \endhtmlonly
1.8 bertrand 17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
1.14 ! bertrand 22: *
1.8 bertrand 23: * .. Scalar Arguments ..
24: * INTEGER INFO, LDA, LDB, N, NRHS
25: * ..
26: * .. Array Arguments ..
27: * INTEGER IPIV( * )
28: * COMPLEX*16 A( LDA, * ), B( LDB, * )
29: * ..
1.14 ! bertrand 30: *
1.8 bertrand 31: *
32: *> \par Purpose:
33: * =============
34: *>
35: *> \verbatim
36: *>
37: *> ZGESV computes the solution to a complex system of linear equations
38: *> A * X = B,
39: *> where A is an N-by-N matrix and X and B are N-by-NRHS matrices.
40: *>
41: *> The LU decomposition with partial pivoting and row interchanges is
42: *> used to factor A as
43: *> A = P * L * U,
44: *> where P is a permutation matrix, L is unit lower triangular, and U is
45: *> upper triangular. The factored form of A is then used to solve the
46: *> system of equations A * X = B.
47: *> \endverbatim
48: *
49: * Arguments:
50: * ==========
51: *
52: *> \param[in] N
53: *> \verbatim
54: *> N is INTEGER
55: *> The number of linear equations, i.e., the order of the
56: *> matrix A. N >= 0.
57: *> \endverbatim
58: *>
59: *> \param[in] NRHS
60: *> \verbatim
61: *> NRHS is INTEGER
62: *> The number of right hand sides, i.e., the number of columns
63: *> of the matrix B. NRHS >= 0.
64: *> \endverbatim
65: *>
66: *> \param[in,out] A
67: *> \verbatim
68: *> A is COMPLEX*16 array, dimension (LDA,N)
69: *> On entry, the N-by-N coefficient matrix A.
70: *> On exit, the factors L and U from the factorization
71: *> A = P*L*U; the unit diagonal elements of L are not stored.
72: *> \endverbatim
73: *>
74: *> \param[in] LDA
75: *> \verbatim
76: *> LDA is INTEGER
77: *> The leading dimension of the array A. LDA >= max(1,N).
78: *> \endverbatim
79: *>
80: *> \param[out] IPIV
81: *> \verbatim
82: *> IPIV is INTEGER array, dimension (N)
83: *> The pivot indices that define the permutation matrix P;
84: *> row i of the matrix was interchanged with row IPIV(i).
85: *> \endverbatim
86: *>
87: *> \param[in,out] B
88: *> \verbatim
89: *> B is COMPLEX*16 array, dimension (LDB,NRHS)
90: *> On entry, the N-by-NRHS matrix of right hand side matrix B.
91: *> On exit, if INFO = 0, the N-by-NRHS solution matrix X.
92: *> \endverbatim
93: *>
94: *> \param[in] LDB
95: *> \verbatim
96: *> LDB is INTEGER
97: *> The leading dimension of the array B. LDB >= max(1,N).
98: *> \endverbatim
99: *>
100: *> \param[out] INFO
101: *> \verbatim
102: *> INFO is INTEGER
103: *> = 0: successful exit
104: *> < 0: if INFO = -i, the i-th argument had an illegal value
105: *> > 0: if INFO = i, U(i,i) is exactly zero. The factorization
106: *> has been completed, but the factor U is exactly
107: *> singular, so the solution could not be computed.
108: *> \endverbatim
109: *
110: * Authors:
111: * ========
112: *
1.14 ! bertrand 113: *> \author Univ. of Tennessee
! 114: *> \author Univ. of California Berkeley
! 115: *> \author Univ. of Colorado Denver
! 116: *> \author NAG Ltd.
1.8 bertrand 117: *
1.14 ! bertrand 118: *> \date December 2016
1.8 bertrand 119: *
120: *> \ingroup complex16GEsolve
121: *
122: * =====================================================================
1.1 bertrand 123: SUBROUTINE ZGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
124: *
1.14 ! bertrand 125: * -- LAPACK driver routine (version 3.7.0) --
1.1 bertrand 126: * -- LAPACK is a software package provided by Univ. of Tennessee, --
127: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.14 ! bertrand 128: * December 2016
1.1 bertrand 129: *
130: * .. Scalar Arguments ..
131: INTEGER INFO, LDA, LDB, N, NRHS
132: * ..
133: * .. Array Arguments ..
134: INTEGER IPIV( * )
135: COMPLEX*16 A( LDA, * ), B( LDB, * )
136: * ..
137: *
138: * =====================================================================
139: *
140: * .. External Subroutines ..
141: EXTERNAL XERBLA, ZGETRF, ZGETRS
142: * ..
143: * .. Intrinsic Functions ..
144: INTRINSIC MAX
145: * ..
146: * .. Executable Statements ..
147: *
148: * Test the input parameters.
149: *
150: INFO = 0
151: IF( N.LT.0 ) THEN
152: INFO = -1
153: ELSE IF( NRHS.LT.0 ) THEN
154: INFO = -2
155: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
156: INFO = -4
157: ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
158: INFO = -7
159: END IF
160: IF( INFO.NE.0 ) THEN
161: CALL XERBLA( 'ZGESV ', -INFO )
162: RETURN
163: END IF
164: *
165: * Compute the LU factorization of A.
166: *
167: CALL ZGETRF( N, N, A, LDA, IPIV, INFO )
168: IF( INFO.EQ.0 ) THEN
169: *
170: * Solve the system A*X = B, overwriting B with X.
171: *
172: CALL ZGETRS( 'No transpose', N, NRHS, A, LDA, IPIV, B, LDB,
173: $ INFO )
174: END IF
175: RETURN
176: *
177: * End of ZGESV
178: *
179: END
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