%0 Journal Article %T Asymptotics of the number of threshold functions on a two-dimensional rectangular grid %A Pentti Haukkanen %A Jorma K. Merikoski %J Mathematics %D 2011 %I arXiv %X Let $m,n\ge 2$, $m\le n$. It is well-known that the number of (two-dimensional) threshold functions on an $m\times n$ rectangular grid is {eqnarray*} t(m,n)=\frac{6}{\pi^2}(mn)^2+O(m^2n\log{n})+O(mn^2\log{\log{n}})= \frac{6}{\pi^2}(mn)^2+O(mn^2\log{m}). {eqnarray*} We improve the error term by showing that $$ t(m,n)=\frac{6}{\pi^2}(mn)^2+O(mn^2). $$ %U http://arxiv.org/abs/1110.3566v2