Applies accelerated proximal gradient algorithm to the l1-regularized quadratic program $$f(\mathbf{x}) + g(\mathbf{x}) = \frac{1}{2}\mathbf{x}^TA\mathbf{x} - d^T\mathbf{x} + \lambda |\mathbf{x}|_1$$
APG_EN2(A, d, x0, lam, alpha, maxits, tol)
p by p positive definite coefficient matrix $$A = (\gamma Om + X^T X/n)$$.
nx1 dimensional column vector.
Regularization parameter for l1 penalty, must be greater than zero.
Step length.
Number of iterations to run
Stopping tolerance for proximal gradient algorithm.
APG_EN2
returns an object of class
"APG_EN2
" including a list
with the following named components
call
The matched call.
x
Found solution.
k
Number of iterations used.
This function is used by other functions and should only be called explicitly for debugging purposes.
Used by: SDAAP
and the SDAAPcv
cross-validation version.