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Jun 16, 2020 at 15:20 comment added Brian Borchers @tBuLi fixed. Thanks for spotting that.
Jun 16, 2020 at 15:19 history edited Brian Borchers CC BY-SA 4.0
added 8 characters in body
Jun 16, 2020 at 15:12 comment added tBuLi Excellent answer. I do think there is one small mistake: in case you include a prior you also have to multiply that by $\lambda$, so the last entry in $d$ should be $\lambda L x_0$.
Feb 4, 2014 at 2:37 comment added Brian Borchers There are lots of methods for selecting the regularization parameter. If you know the noise level in $b$, then you can use it as a basis for selecting $\lambda$ (pick the largest lambda that still results in statistically adequate fit to the data.) A simple heuristic that is commonly used in practice is the L-curve criterion- plot $\| Ax - -b \|$ vs. $\| x \|$, and look for a value of $\lambda$ that gives a "corner" solution that is pareto optimal. In practice, the choice of $\lambda$ is often simply subjective- what makes the solution look good.
Feb 4, 2014 at 1:13 comment added user3259573 Thanks Brian. I implemented that, and it runs. I have one more question: How do I choose the value of lambda?
Feb 1, 2014 at 19:15 history edited Brian Borchers CC BY-SA 3.0
added details to the extension at the end of the asnwer.
Feb 1, 2014 at 16:45 comment added k20 Nice +1 I would upvote but I'm too lazy to register.
Feb 1, 2014 at 16:31 history answered Brian Borchers CC BY-SA 3.0