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Hello Roberto,
I created an example which reproduces my problem:
#include <ppl.hh>
int main(int argc, char** argv) {
using namespace Parma_Polyhedra_Library::IO_Operators;
Parma_Polyhedra_Library::C_Polyhedron mPolyhedron = Parma_Polyhedra_Library::C_Polyhedron(2, Parma_Polyhedra_Library::EMPTY); Parma_Polyhedra_Library::Variable a(0); Parma_Polyhedra_Library::Variable b(1);
Parma_Polyhedra_Library::Linear_Expression polynom; polynom.set_coefficient(a, 1); polynom.set_coefficient(b, 3); polynom.set_inhomogeneous_term(-4);
std::cout << "Polynom: " << polynom << std::endl;
Parma_Polyhedra_Library::Constraint constraint; constraint = polynom <= 0;
std::cout << "Constraint: "; constraint.print(); std::cout << " Dimension: " << constraint.space_dimension() << std::endl;
mPolyhedron.add_constraint(constraint);
std::cout << "Polyhedron: "; mPolyhedron.print(); std::cout << std::endl; }
Am 12/06/14 12:05, schrieb Roberto Bagnara:
On 11/06/2014 16:29, Stefan Schupp wrote:
I am currently trying to create a Polytope from a matrix and a vector. Therefore I create linear expressions from the coefficients of the matrix in combination with the associated PPL-Variables. Afterwards I can add an inhomogenous term from the given vector.
As far as I read the documentation I can construct a Polytope naturally by adding constraints. These constraints are supposed to be constructed from a relation of either a linear expression and a constant (my inhomogenuous term, if you want to put it that way) or a relation from two linear expressions. I tried both ways, but the constraint created seems to be empty. How am I supposed to create and use the needed Constraints?
Short example:
Linear expression: A + 3*B - 5 (when printed) resulting constraint: 0 >= -5 (created by:
Parma_Polyhedra_Library::Constraint constraint = expr <= 0
, where expr is the linear expression)
Hello Stefan,
please send a piece of code that we can examine, compile and execute. Kind regards,
Roberto
The created output is: Polynom: A + 3*B - 4 Constraint: 0 >= -4 Dimension: 0 Polyhedron: false
I thought the constraint created should be something like A + 3*B - 4 <= 0.
Best regards, Stefan
- -- Stefan Schupp M.Sc. RWTH Aachen University Computer Science Department, Informatik 2 D-52056 Aachen, Germany http://www-i2.informatik.rwth-aachen.de/i2/schupp/ Tel.: +49 241 80 21243