Talk:Sparse approximation

The sentence "The underlying motivation for sparse decomposition problems is that even though the observed values are in high-dimensional $m$ space, the actual signal is organized in some lower-dimensional subspace ($k \ll m$)." introduces the the symbol $k$ without explicit definition. Is $k$ a typo that should be $p$? If so, there's a contradiction between $k \ll m$ and m \ll p. Is $k$ the actual number of non-zero components of the decomposition, to be found by the analysis?SMesser (talk) 16:15, 17 January 2014 (UTC)