Marching Cubes - Holes in Mesh

Question

I am working on the university project of computation graphics, I have implemented the marching cubes algorithm following the guidelines of http://paulbourke.net/geometry/polygonise/. When I test the algorithm without linear interpolation i get an isosurface without holes, when I use interpolation for the edges I have some holes on the isosurface, for example:

here is the code of the linear interpolation

public PVector LinearInterp(PVector p1, PVector p2, int valp1, int valp2)
{
  
   double mu;
   PVector p= new PVector();
 
  if(compare(p2,p1))
   {
     PVector temp;
     temp=p1;
     p1=p2;
     p2=temp;
   
   }
   if(abs(valp1-valp2)>0.00001)
   {
      p.x=p1.x+((p2.x-p1.x)/(valp2-valp1)*(isovalue-valp1));
      p.y=p1.y+((p2.y-p1.y)/(valp2-valp1)*(isovalue-valp1));
      p.z=p1.z+((p2.z-p1.z)/(valp2-valp1)*(isovalue-valp1));
   }
   else 
     p=p1;
    return p;
}
 

public boolean compare(PVector p1, PVector p2)
{ // p1 < p
  if(p1.x<p2.x)
  return true;
  else if(p1.x > p2.x)
  return false;
   
  if(p1.y<p2.y)
  return true;
  else if(p1.y > p2.y)
  return false;
   
  if(p1.x<p2.x)
  return true;
  else if(p1.z > p2.z)
  return false;
 
  return false;
}

SOLUTION: The problem was the function to calculate the interpolation point, here is the correct function

 public PVector LinearInterp(PVector p1, PVector p2, int valp1, int valp2)
        {
          
            PVector p= new PVector();
            p.x = p1.x;
            p.y = p1.y;
            p.z = p1.z;
            float val=0;
            if(p1.x != p2.x)
            {
              val = p2.x + (p1.x - p2.x) * (isovalue-valp2)/(valp1-valp2);
              p.x=val;
            }else if(p1.y!=p2.y)
            {
                val = p2.y + (p1.y-p2.y)*(isovalue-valp2)/(valp1-valp2);
                p.y=val;
            }
            else
            {
                val=p2.z+(p1.z-p2.z)*(isovalue-valp2)/(valp1-valp2);
                p.z=val;
            }
            return p;
      }