[PPL-devel] Help regarding floating point constraints

[Habeeb P]

Hi,

I am a Ph.D. student at the Indian Institute of Science, Bangalore, India.


I have been working on a project that requires a polyhedron.

The polyhedron has constraints with floating-point variables, as shown below in the following code snippet.
Wher p,u,v and w are floating-point values between 0 and 1, u+v+w =1.


Variable xp0(0);
Variable yp0(1);
Variable zp0(2);

Variable u(0);
Variable v(1);
Variable w(2);
Variable p(0);


int x0 = vertices[insideVertex*3+0];
int y0 = vertices[insideVertex*3+1];
int z0 = vertices[insideVertex*3+2];

int x1 = vertices[outsideVertex*3+0];
int y1 = vertices[outsideVertex*3+1];
int z1 = vertices[outsideVertex*3+2];


pd->add_constraint( u+v+w == 1);
pd->add_constraint(  u>=0) ;
pd->add_constraint( v>=0);
pd->add_constraint( w>=0);
pd->add_constraint( p>=0);
// pd->add_constraint( q>=0);
//  pd->add_constraint( p+q ==1);
pd->add_constraint(  ( (( p*(x0 - xp0)+ (1-p)*(x1 - xp0)) == (u*-35821+v*0+(w)*35821)) );
pd->add_constraint( ((p*(y0 - yp0)+  (1-p)*(y1 - yp0)) == (u*35821+v*0+(w)*35821)) );
pd->add_constraint( ((p*(z0 - zp0)+  (1-p)*(z1 - zp0)) == (u*-100000+v*0+(w)*-100000)));

pd->add_constraint( -( (24*p*(x0-xp0))+(24*(1-p)*(x1-xp0))) >= ((PixelX - 24)*(p*(z0-zp0)+ (1-p)*(z1-zp0)) ) );
pd->add_constraint( -( (24*p*(x0-xp0))+(24*(1-p)*(x1-xp0))) < ((PixelX+1 - 24)*(p*(z0-zp0)+ (1-p)*(z1-zp0)) ) );

pd->add_constraint( ( 24*p*(y0-yp0) + 24* (1-p)*(y1-yp0) ) >= ( (PixelY-24) * (p*(z0-zp0)+ (1-p)*(z1-zp0)) ) );
pd->add_constraint( ( 24*p*(y0-yp0) + 24* (1-p)*(y1-yp0) ) < ( (PixelY-24+1) * (p*(z0-zp0)+ (1-p)*(z1-zp0)) ) );





While compiling the program, I am getting the following error;


error: no match for ‘operator*’ (operand types are ‘Parma_Polyhedra_Library::Variable’ and ‘Parma_Polyhedra_Library::Linear_Expression’)
  116 |                  pd->add_constraint(  ( (( p*(x0 - xp0)+ (1-p)*(x1 - xp0)) == (u*-35821+v*0+(w)*35821)) );
      |                                            ~^~~~~~~~~~~
      |                                            |     |
      |                                            |     Parma_Polyhedra_Library::Linear_Expression
      |                                            Parma_Polyhedra_Library::Variable


Is there any way to get rid of this error?


Is it possible to write my constraints using PPL (using either floating-point expression or intervals)?



Thanks
HABEEB
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