正交投影到子空间/欧式投影到子空间或仿射空间或凸集

orthogonal projection onto a convex
orthogonal projection onto a subspace
orthogonal projection onto affine space
Euclidean projection on a set….

Then we project w−−1 onto the Set Cf.The new iterate w−−2 is determined by minimizing the distantce between w1 and Cf,i.e.,

w−−2=argminw−∈Cs||w−−1−w−−||(6)

Equantion 6 is the ordinary orthognonal projection operation onto the set Cf∈RN+1,其中w1∈RN+1.

参考文献：
1、Denoising Using Projection Onto Convex Sets (POCS) Based Framework_2013 公式（6）