# Label number for a domain with hole

hi to everyone,

I created a square with a hole using the commands “square” and then “trunc”.

I wrote the following code in FF++ for the square domain with a hole :

//parameters
real x0=-7.,y0=-7.;//left bottom node of the omega square
real xF=7.,yF=7.;//right top node of the omega square
int n=7;
int N =2^n;//number of partition in each direction
real xT=-2.1,yT=-2.1;//left bottom node of TRAC square
real xTF=2.1,yTF=2.1;//right top node of TRAC square

// domain of the problem

int[int] outer=[1,1,1,1], bTRAC=[2,2,2,2];

mesh Th = square(N,N,[x0+(xF-x0)*x ,y0+(yF-y0)*y],label=outer, region=1);

mesh ThTRAC = square(N,N,[xT+(xTF-xT)*x,yT+(yTF-yT)*y],label=bTRAC,region=2);

mesh Thwithole=trunc(Th,((x<xT | x>xTF|y<yT) | (x<xT | x>xTF| y>yTF)));

I know that if add the following lines:

int outerboundary=1;
mesh Thwithole=trunc(Th,((x<xT | x>xTF|y<yT) | (x<xT | x>xTF| y>yTF)),label=outerboundary);

Then FF++ would assign the same label for each of the boundaries.
But, I would like to assign different labels for each of the boundaries, i.e., for the inner boundary and for the outer boundary.