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/* Test the MIP_Problem class with instances that require a watchdog timer.
Copyright (C) 2001-2010 Roberto Bagnara <bagnara@cs.unipr.it>
Copyright (C) 2010-2016 BUGSENG srl (http://bugseng.com)
This file is part of the Parma Polyhedra Library (PPL).
The PPL is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
The PPL is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307, USA.
For the most up-to-date information see the Parma Polyhedra Library
site: http://bugseng.com/products/ppl/ . */
#include "ppl_test.hh"
#include <limits>
namespace {
class Timeout : virtual public std::exception,
public Parma_Polyhedra_Library::Throwable {
public:
const char* what() const throw() {
return "Timeout in refine1.cc";
}
void throw_me() const {
throw *this;
}
int priority() const {
return 0;
}
Timeout() {
}
~Timeout() throw() {
}
};
Timeout t;
bool test01() {
Variable A(0);
Variable B(1);
Variable C(2);
Variable D(3);
Linear_Expression cost(10*A + 3*B);
Constraint_System cs;
cs.insert(A + B >= 0);
cs.insert(B >= 0);
cs.insert(B == 3);
cs.insert(2*C + 2*D == 9);
MIP_Problem mip = MIP_Problem(cs.space_dimension(), cs, cost, MINIMIZATION);
Coefficient num_kr = -21;
Coefficient den_kr = 1;
Coefficient num;
Coefficient den;
Generator pg = mip.optimizing_point();
mip.evaluate_objective_function(pg, num, den);
nout << "Optimum value = " << num << "/" << den << endl;
if (num != num_kr || den != den_kr)
return false;
nout << "Optimizing point = ";
print_generator(pg);
Generator pg_kr = point(-6*A + 6*B + 9*D, 2);
if (pg != pg_kr)
return false;
// Set Variable A to be constrained to have an integer value.
mip.add_to_integer_space_dimensions(Variables_Set(A));
pg = mip.optimizing_point();
mip.evaluate_objective_function(pg, num, den);
nout << "Optimum value = " << num << "/" << den << endl;
if (num != num_kr || den != den_kr)
return false;
nout << "Optimizing point = ";
print_generator(pg);
if (pg != pg_kr)
return false;
// Set Variable B to be constrained to have an integer value.
mip.add_to_integer_space_dimensions(Variables_Set(B));
pg = mip.optimizing_point();
mip.evaluate_objective_function(pg, num, den);
nout << "Optimum value = " << num << "/" << den << endl;
if (num != num_kr || den != den_kr)
return false;
nout << "Optimizing point = ";
print_generator(pg);
if (pg != pg_kr)
return false;
// Set Variable C to be constrained to have an integer value.
mip.add_to_integer_space_dimensions(Variables_Set(C));
pg = mip.optimizing_point();
mip.evaluate_objective_function(pg, num, den);
nout << "Optimum value = " << num << "/" << den << endl;
if (num != num_kr || den != den_kr)
return false;
nout << "Optimizing point = ";
print_generator(pg);
if (pg != pg_kr)
return false;
// Set Variable D to be constrained to have an integer value.
// This will cause branch-and-bound not to terminate any longer.
mip.add_to_integer_space_dimensions(Variables_Set(D));
try {
// Set a 2 seconds timeout.
Parma_Polyhedra_Library::Watchdog
w(200, abandon_expensive_computations, t);
pg = mip.optimizing_point();
// We should never get here.
abandon_expensive_computations = 0;
nout << "unexpected termination" << endl;
return false;
}
catch (const Timeout&) {
abandon_expensive_computations = 0;
nout << "timeout, as expected" << endl;
return true;
}
#if !PPL_WATCHDOG_OBJECTS_ARE_SUPPORTED
// If Watchdog objects are not supported, an std::logic_error exception
// will be thrown: this is normal.
catch (const std::logic_error& e) {
nout << "std::logic_error exception caught: \n" << e.what() << std::endl;
exit(0);
}
#endif // !PPL_WATCHDOG_OBJECTS_ARE_SUPPORTED
catch (const std::overflow_error& e) {
abandon_expensive_computations = 0;
if (std::numeric_limits<Coefficient>::is_integer
&& std::numeric_limits<Coefficient>::is_bounded
&& std::numeric_limits<Coefficient>::radix == 2
&& std::numeric_limits<Coefficient>::digits == 7) {
// Overflow is OK with 8-bit coefficients.
nout << "arithmetic overflow (" << e.what() << "),"
" possible with 8-bit coefficients" << endl;
return true;
}
else
// Overflow errors should be propagated in all other cases.
throw;
}
catch (...) {
abandon_expensive_computations = 0;
nout << "unexpected exception" << endl;
return false;
}
}
} // namespace
BEGIN_MAIN
DO_TEST(test01);
END_MAIN
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