Annotation of rpl/lapack/lapack/zptsv.f, revision 1.9
1.9 ! bertrand 1: *> \brief \b ZPTSV
! 2: *
! 3: * =========== DOCUMENTATION ===========
! 4: *
! 5: * Online html documentation available at
! 6: * http://www.netlib.org/lapack/explore-html/
! 7: *
! 8: *> \htmlonly
! 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">
! 15: *> [TXT]</a>
! 16: *> \endhtmlonly
! 17: *
! 18: * Definition:
! 19: * ===========
! 20: *
! 21: * SUBROUTINE ZPTSV( N, NRHS, D, E, B, LDB, INFO )
! 22: *
! 23: * .. Scalar Arguments ..
! 24: * INTEGER INFO, LDB, N, NRHS
! 25: * ..
! 26: * .. Array Arguments ..
! 27: * DOUBLE PRECISION D( * )
! 28: * COMPLEX*16 B( LDB, * ), E( * )
! 29: * ..
! 30: *
! 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: *
! 106: *> \author Univ. of Tennessee
! 107: *> \author Univ. of California Berkeley
! 108: *> \author Univ. of Colorado Denver
! 109: *> \author NAG Ltd.
! 110: *
! 111: *> \date November 2011
! 112: *
! 113: *> \ingroup complex16OTHERcomputational
! 114: *
! 115: * =====================================================================
1.1 bertrand 116: SUBROUTINE ZPTSV( N, NRHS, D, E, B, LDB, INFO )
117: *
1.9 ! bertrand 118: * -- LAPACK computational routine (version 3.4.0) --
1.1 bertrand 119: * -- LAPACK is a software package provided by Univ. of Tennessee, --
120: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.9 ! bertrand 121: * November 2011
1.1 bertrand 122: *
123: * .. Scalar Arguments ..
124: INTEGER INFO, LDB, N, NRHS
125: * ..
126: * .. Array Arguments ..
127: DOUBLE PRECISION D( * )
128: COMPLEX*16 B( LDB, * ), E( * )
129: * ..
130: *
131: * =====================================================================
132: *
133: * .. External Subroutines ..
134: EXTERNAL XERBLA, ZPTTRF, ZPTTRS
135: * ..
136: * .. Intrinsic Functions ..
137: INTRINSIC MAX
138: * ..
139: * .. Executable Statements ..
140: *
141: * Test the input parameters.
142: *
143: INFO = 0
144: IF( N.LT.0 ) THEN
145: INFO = -1
146: ELSE IF( NRHS.LT.0 ) THEN
147: INFO = -2
148: ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
149: INFO = -6
150: END IF
151: IF( INFO.NE.0 ) THEN
152: CALL XERBLA( 'ZPTSV ', -INFO )
153: RETURN
154: END IF
155: *
1.8 bertrand 156: * Compute the L*D*L**H (or U**H*D*U) factorization of A.
1.1 bertrand 157: *
158: CALL ZPTTRF( N, D, E, INFO )
159: IF( INFO.EQ.0 ) THEN
160: *
161: * Solve the system A*X = B, overwriting B with X.
162: *
163: CALL ZPTTRS( 'Lower', N, NRHS, D, E, B, LDB, INFO )
164: END IF
165: RETURN
166: *
167: * End of ZPTSV
168: *
169: END
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