lattice.block

block the lattice by factor, switching to smaller lattice.

block the lattice by factor, switching to smaller lattice. lattice.size() must be element-by-element divisible by factor

({2,2,2}) reduces current lattice size by 2 to each direction.

Note

Previously used Field variables cannot be used in onsites(). However, their content can be blocked to new Field with Field<T>::block_from(), which copies the content from the blocked (sparse) set of sites;

Field<double> a;
a[ALL] = X.x() + X.y() + X.z();   // in 3d
 
CoordinateVector factor{2,2,2};
 
lattice.block(factor);
Field<double> b;
 
b.block_from(a);               // Now b contains 0+0+0, 2+0+0 ...
b[ALL] = -b[X];                // Do operations, here flip sign
// onsites(ALL) a[X] = 1;      // ERROR, a belongs to original lattice
b.unblock_to(a);               // copy content of b back to a on blocked sites,
                               // leaving other sites of a
lattice.unblock();             // return to original lattice
 
// Now a can be used, it contains -(0+0+0), 1+0+0, -(2+0+0), ...

Note

Fields which were not used previously can be used in blocked levels, or their association (and content) can be deleted with .clear():

Field<double> a,b;
a = 1;
lattice.block({2,2,1});
b = 2;       // OK, b was not used before blocking
a = 3;       // ERROR; a belongs to non-blocked lattice
a.clear();
a = 3;       // OK, now a belongs to blocked lattice

Returns

lattice_struct * to blocked lattice