# Last day of inverse theory :-(

Today was our last inverse theory class.  We didn’t have time to cover the conjugate gradient method, which was too bad, I was really hoping we would get to that stuff.  One of our lab group’s weekly readings was on the double-differencing technique for earthquake location.  In it, they described using a conjugate gradient-type method called LSQR.   It’s supposed to allow you to avoid inverting a giant matrix when solving inverse problems.  From my very basic understanding, it finds the answer in a sort of iterative way, by making successive guesses to find the minimum in some objective surface.  The good news is that Matlab has a canned lsqr function, so I could just try it out and see for myself.  Although the canned function can be a bad thing, because then you can just treat it like a black box.

## 7 thoughts on “Last day of inverse theory :-(”

1. Vera says:

i liked this one. even though you were grumpy at the bus stop.

2. haha – well, I wasn’t really quite as grumpy as I look in that drawing.

3. Jocelyn says:

I understand Trooper so well!!! Sun, come out!!!

4. Carol says:

Love your sketches! But what about the hair dye? Are you a new color?

5. Mom – I think we ALL understand Trooper! I want to lay out in the sun too 🙂 … maybe after finals week!

Carol – It wasn’t too drastic. Just a couple of shades darker.

6. Vera says:

You should come visit us in sunny ol’ Texas – i can GUARANTEE full sunshine – each day of your visit. If i drew a comic of my day – the cloud would not look menacing – there would be no cloud. Maybe a very wispy, far a way cloud. A lonely cloud. Almost taunting us Texans with its far-away presence.
As backwards as it is – we do have wireless, so you could correspond with colleagues and such. I promise you’d get work done. We could do a thing where you’d get no food until you accomplished a certain amount of research each day of your visit.
VISIT US! and i’m kidding – plenty of food. no quotas.

Jocelyn (although I feel more appropriate with Mrs. Weirathmueller) – what happened to your FB – i was about to leave you a comment, and could not find you!

7. Carol says:

It’s sunny in NC too! If coming East fits into your schedule sometime we ALL would be thrilled!