Annotation of rpl/lapack/lapack/zgesv.f, revision 1.8
1.8 ! bertrand 1: *> \brief <b> ZGESV computes the solution to system of linear equations A * X = B for GE matrices</b> (simple driver)
! 2: *
! 3: * =========== DOCUMENTATION ===========
! 4: *
! 5: * Online html documentation available at
! 6: * http://www.netlib.org/lapack/explore-html/
! 7: *
! 8: *> \htmlonly
! 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">
! 15: *> [TXT]</a>
! 16: *> \endhtmlonly
! 17: *
! 18: * Definition:
! 19: * ===========
! 20: *
! 21: * SUBROUTINE ZGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
! 22: *
! 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: * ..
! 30: *
! 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: *
! 113: *> \author Univ. of Tennessee
! 114: *> \author Univ. of California Berkeley
! 115: *> \author Univ. of Colorado Denver
! 116: *> \author NAG Ltd.
! 117: *
! 118: *> \date November 2011
! 119: *
! 120: *> \ingroup complex16GEsolve
! 121: *
! 122: * =====================================================================
1.1 bertrand 123: SUBROUTINE ZGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
124: *
1.8 ! bertrand 125: * -- LAPACK driver routine (version 3.4.0) --
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..--
1.8 ! bertrand 128: * November 2011
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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