Before revision: We study the least squares problem x_{b,\omega} := \min _{x \in S} \|(A + \omega I)^{-1/2} (b - Ax)\|_2, with A = A^*, for a subspace S of F^n (F = R or C), and \omega > -min(A).
After revision: We study the least squares problem x_{b,\omega} := \text{arg min _{x \in S} \|(A + \omega I)^{-1/2} (b - Ax)\|_2, with A = A^*, for a subspace S of F^n (F = R or C), and \omega > -min(A).