A new approach of conditions on for s-sparse recovery δ2s（φ）

In this paper, we provide a unified expression to obtain the conditions on the restricted isometry constant δ2s（φ）. These conditions cover the important results proposed by Candes et al. and each of them is a sufficient condition for sparse signal recovery. In the noiseless case, when δ2s（φ） satisfies any one of these conditions, the s-sparse signal can be exactly recovered via （11） constrained minimization.