P is the population count for the census tract I, to which the grid cell i belongs;
gridi F is the value resulted from the operation over the spatial indicator variables for the grid cell i
(as weight average or fuzzy operators over fuzzy indicator variables);
gridI F is the sum of all
gridi F where i is a valid grid cell for the census tract I.
At the end of the procedure, population density initially depicted by the limits of census tracts (polygonal)
is presented in regular 1x1km cells, according to defined relationships between indicator variables and
population presence