We present an application of wavelet theory in partial differential equatio
ns. We study the wavelet fundamental solutions to the heat equation. The he
at evolution of an initial wavelet state is called a heatlet. Like wavelets
for the L-2 space, heatlets are "atomic" heat evolutions in the sense that
any general heat evolution can be "assembled" from a heatlet according to
some simple rules. We study the basic properties and algorithms of heatlets
and related functions. (C) 2000 Academic Press.