[PPL-devel] Help regarding floating point constraints

[Roberto Bagnara]

Hi.

The error message is quite clear:

  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

you are trying to apply operator * (multiplication) to a Variable (p)
and a Linear_Expression (x0 - xp0), but there is no suitable overloading
of the * operator, as this could result in a non-linear expression.
In the PPL you can only directly work with linear expressions.
Kind regards,

    Roberto

On 06/03/22 09:44, Habeeb P wrote:
> Hi,
> 
> Thanks for the reply.
> 
> Please see, I have attached the code.
> 
> 
> 
> 
> 
> Thanks
> HABEEB
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *From:* Roberto Bagnara <bagnara at cs.unipr.it>
> *Sent:* Sunday, March 6, 2022 12:45 PM
> *To:* Habeeb P <habeebp at iisc.ac.in>
> *Cc:* The Parma Polyhedra Library developers' list <ppl-devel at cs.unipr.it>
> *Subject:* Re: [PPL-devel] Help regarding floating point constraints
> External Email
> 
> 
> Hello Habeeb.
> 
> Can you please attach a self-contained C++ program we
> can use to try reproducing your problem?
> 
> Which version of the PPL are you using?
> We recommend  the current Git version, devel branch.
> You can find the repository at:
> 
>     git://git.bugseng.com/ppl/ppl.git
> 
> Thanks,
> 
>      Roberto
> 
> 
> 
> On 23/01/22 18:54, Habeeb P wrote:
>> 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 f*loating-poin*t values *between 0 and 1, u+v+w =1.*
>>
>>
>> Variablexp0(0);
>> Variableyp0(1);
>> Variablezp0(2);
>>
>> Variableu(0);
>> Variablev(1);
>> Variablew(2);
>> Variablep(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
>>
>> _______________________________________________
>> PPL-devel mailing list
>> PPL-devel at cs.unipr.it
>> https://www.cs.unipr.it/mailman/listinfo/ppl-devel <https://www.cs.unipr.it/mailman/listinfo/ppl-devel>
> 
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