1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
////////////////////////////////////////////////////////////////////////////////
//
// LPinterface.cc
//
// produced: 2001/10/28 jr
// last change: 2001/10/28 jr
//
////////////////////////////////////////////////////////////////////////////////
#include <mutex>
#include "LPinterface.hh"
namespace topcom {
bool LPinterface::_is_initialized = false;
std::mutex LPinterface::_init_mutex;
// constructors:
LPinterface::LPinterface(const Matrix& m, const LabelSet& support) :
_solptr(0),
_support(support) {
if (!_is_initialized) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "LPinterface::LPinterface(const Matrix& m, const LabelSet& support):"
<< " Lp solver cdd was called but not initialized - exiting" << std::endl;
exit(1);
}
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "building LP matrix ..." << std::endl;
}
_solver = dd_DualSimplex;
// note that the coefficient matrix m is transposed for efficiency reasons;
_m = m.coldim(); // number of rows
_n = m.rowdim() + 1; // number of cols
_matrixptr = dd_CreateMatrix(_m, _n);
_matrixptr->objective = dd_LPmax;
_matrixptr->representation = dd_Inequality;
_matrixptr->numbtype = dd_Rational;
for (size_type i = 0; i < m.coldim(); ++i) {
// build cdd's matrix row by row;
// recall that the coefficient matrix m is transposed for efficiency reasons;
// the first entry is MINUSONE in every row because
// its meaning in cdd is is "minus the right hand side":
dd_set_R(_matrixptr->matrix[i][0], FieldConstants::MINUSONE);
for (size_type j = 0; j < m.rowdim(); ++j) {
// because the first column contains the data for the right hand side
// (which is MINUSONE) we need to shift the column index by one;
// again, we have to use the coefficient matrix m in a transposed way:
dd_set_R(_matrixptr->matrix[i][j+1], m(j, i));
}
}
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
dd_WriteMatrix(stderr, _matrixptr);
}
// cdd allows to automatically generate an auxilliary LP for finding an interior point:
// dd_LPPtr auxlpptr = dd_Matrix2LP(_matrixptr, &_err);
// _lpptr = dd_MakeLPforInteriorFinding(auxlpptr);
_lpptr = dd_Matrix2Feasibility(_matrixptr, &_err);
if (!_lpptr) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "error in generating LP." << std::endl;
dd_WriteErrorMessages(stderr, _err);
exit(1);
}
// dd_FreeLPData(auxlpptr);
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "... done." << std::endl;
}
}
// functions:
bool LPinterface::has_interior_point(Vector* heightsptr) {
// caller must take care of a pointer to a Vector of appropriate size, pre-filled with ZERO:
if (!_is_initialized) {
std::cerr << "LPinterface::has_interior_point():"
<< " LP solver cdd was called but not initialized - exiting" << std::endl;
exit(1);
}
// Check feasibility with cdd LP library:
bool result = dd_LPSolve0(_lpptr, _solver, &_err);
if (_err != dd_NoError) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "error in solving LP." << std::endl;
dd_WriteErrorMessages(stderr, _err);
exit(1);
}
if (_lpptr->LPS == dd_Inconsistent) {
// the LP is infeasible:
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "The feasible region is empty." << std::endl;
}
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "... done." << std::endl;
}
return false;
}
// otherwise the LP is feasible:
if (CommandlineOptions::output_heights()) {
// output a height vector:
_solptr = dd_CopyLPSolution(_lpptr);
Field maxheight(FieldConstants::ONE);
for (dd_rowrange j = 0; j < (_solptr->d) - 1; j++) {
const Field x_j = Field(_solptr->sol[j+1]);
if (maxheight - FieldConstants::ONE < x_j) {
maxheight = x_j + FieldConstants::ONE;
}
}
for (dd_rowrange j = 0; j < (_solptr->d) - 1; j++) {
const Field x_j = Field(_solptr->sol[j+1]);
if (_support.contains(j)) {
heightsptr->at(j) = x_j;
if (CommandlineOptions::debug()) {
std::cerr << "-- point " << j << " used, assigning height " << x_j << " --" << std::endl;
}
}
else {
if (CommandlineOptions::debug()) {
std::cerr << "-- point " << j << " unused, assigning height " << maxheight << " --" << std::endl;
}
heightsptr->at(j) = maxheight;
}
}
if (CommandlineOptions::debug()) {
std::cerr << "used points: " << _support << std::endl;
std::cerr << "optimal slack: ";
dd_WriteNumber(stderr, _solptr->optvalue);
std::cerr << std::endl;
}
}
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "... done." << std::endl;
}
return true;
}
}; // namespace topcom
// eof LPinterface.cc
|
