Number of degrees of freedom

[prj]

mesh ThCoil = trunc(Th, region == Coil);
varf vPoi(u,v)
    =int2d(ThCoil) (sig * Grad(u)' * Grad(v))//'
    +on(CoilTerminalIn, u=0)
    +on(CoilTerminalOut, u=1);
fespace PhCoil(ThCoil, P1);
matrix Poi = vPoi(PhCoil,PhCoil);
cout << "sizePoi " << Poi.n << endl;