// A Field contains the values of a single field (phi,
// error, etc.) across all levels.

class Field {
    Patch [1d] patches;
    double [1d] [3d] grids;

    Field(Patch [1d] patches) {
	this.patches = patches;
	grids = new double [patches.domain()] [3d];
    }

    Field replicate() {
	Field f = new Field(patches);
	// Make local copy of patch array, and copy patches.
	f.patches = new Patch [patches.domain()];
	f.patches.copy(patches);
	f.grids.copy(grids);
	return f;
    }
}