# [PPL-devel] Linear constraint solving example with floating point co-efficients

Roberto Bagnara bagnara at cs.unipr.it
Wed Aug 24 08:34:08 CEST 2011

```On 08/23/11 15:31, Mahesh Nanjundappa wrote:
> Hi all,
>
> Please don't feel annoyed by this request. I did try for looking for examples in the folder I downloaded and in the manual. But couldnt find what I was looking for.
>
> I'm looking for a simple example where a linear constraint system with floating point coefficients (variables can also take floating point values) is solved and output is printed to either file or stdout. I don't have strict requirement to number of decimal points it has to be accurately computed. I'm fine with just 2 decimal points.
>
> The system can be as simple as this,
>
> 1.2*x + 2.3y <= 8.2
> 2.2*x + 1.4*y <= 7.1
>
> This one example I tried out but with integer coefficients.
> #include <ppl.hh>
> #include "ppl_c.h"
>
> using namespace Parma_Polyhedra_Library;
>
> int main()
> {
>
> Variable x(0);
> Variable y(1);
> Constraint_System CS;
>
> Linear_Expression LE1 = 1*x + 2*y;
> Linear_Expression LE2 = 2*x + 1*y;
>
> CS.insert(LE1 <= 7);
> CS.insert(LE2 <= 5);
>
> C_Polyhedron P(CS);
>
> return 0;
> }
>
> It would be great if someone can help me out with this by providing an example or code for the system I described earlier.
>
> Mahesh

Hi Mahesh.

There is really no way you can use the PPL without even looking
at its documentation.
Good luck,

Roberto

--
Prof. Roberto Bagnara
Applied Formal Methods Laboratory
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it

```