Nonlinear least squares / Fish burrito

Posted by jeff on Jun 22nd, 2008

When you devote almost all waking energy to our startup, it's not uncommon to find yourself eating and working simultaneously.  Today the dynamic duo is a fish burrito and nonlinear least squares regression (NLLS).

The duo

While the burrito is still hot, let's dive into a little compare/contrast.

Many of you may not be familiar with one of these items, so I'll give that item a quick introduction:  A fish burrito is a mexican entree fashioned most typically out of fish, lettuce, a tortilla, and an interstitial sauce of some kind.

Now that we've covered that, you are probably thinking, man, that's almost identical to NLLS.

And you're right.

  • Both the burrito and the mathematical technique are customizable.
  • Both are subject to local maxima -- if you start looking for a fish burrito in the wrong town, you will end up with the best of the worst.  NLLS will end up with with a solution near the initial guess, but not necessarily the best overall.  Overcoming this problem, in both cases, can be done by randomly jumping around periodically (with an airplane and random number generator, respectively).
  • When someone says "fish burrito," there's obviously a lot of ambiguity.  It could mean an authentic, south-of-the-border creation -- a homemade fish burrito fashioned from leftovers -- or, as in today's case, a fish burrito from Illegal Pete's.  Saying "Nonlinear least squares" is equally unspecific.  Everyone's left wondering, do you mean a gradient-descent NLLS?  Do you mean MATLAB's lsqnonlin function?  Or, as in today's case, do you mean the Levenberg-Marquardt algorithm?

Despite these similarities, we can't end without pointing out the key difference:

  • Fish burritos do not require an estimate of the Jacobian.

Not needed

Office away from office

Posted by jeff on Jun 21st, 2008

The office

Because the walk to Sydney's coffee was just too far away (and closed on weekends).

A podcast

Posted by jeff on Jun 17th, 2008

Three weeks in and Andrew Hyde is starting to sneak up on TechStars companies and record them in their natural environments.  Last night he caught us at around 9pm and captured this brief podcast.  Listen in to hear about our first three weeks.

Here's an old video of the rear-projection physics whiteboard referenced in the podcast. Maybe one of these days we'll set it up in the Bunker and record the creative madness that ensues.

A Fortnight of Many First’s

Posted by abhishek on Jun 12th, 2008

We are two weeks into Techstars, in the beautiful city of Boulder, Colorado, and it has been wonderful. There is so much to experience when you are surrounded by a group of cool people you haven’t met before, away from home, being a part of something fresh and new. Talking about experiences, here is a list of things I did for the first time ever, after coming to Boulder...

The First ‘Startup Experience’

How is being a part of a startup, different from working for an established behemoth of a firm? Well, frankly, I think of an established company as a 100 page book of ‘connect the dots’, and think of startup as play-dough. One is a monotonous, rarely intriguing, to be repeated over and over again, with a high success rate. Play-Dough on the other hand, well, it’s so much more fun, so much more creative, and you may not end up with what you thought you were making! (not hinting at any Techstars startups… ).

The First Ice Hockey Match

So many of our interests are programmed into us subconsciously. Sports is certainly one of them.

We may find a zillion reasons for why your favorite sport is supposed to be the best, but in the end, it’s the common passion that our people have for it, that sucks us into it. And, it can happen at any age. Vikas and Jeff, being from Michigan, are hard core Red Wing fans, and asked me and Shun to watch the Stanley cup finals with them, and it was great. (Actually, if you count the ‘Bart Vs Lisa’ episode from The Simpsons, it was my second ice hockey match). I now find Ice Hockey cool...

The First Waffle

Most of the western food that has influenced the east, is fast-food from USA, pastas and Co. from Italy and Mexican food from, well, USA (it’s more like “Mexican” food). So I can safely claim that you won’t find waffles anywhere in India. I had one with pecans the other day, and it was awesome.

The First Martini


(I am being forced to write this….)

I have been above the age limit for some time, and the other day, I decided to take the plunge by getting a vodka+wine mixture, called, The Strawberry Confusion. It contained strawberries, and well, couldn’t figure anything else out. Maybe that’s the confusion part of it. A drink, so true to it’s name. The exclusiveness of the moment called for a picture to be taken using Jeff's ever-handy camera phone.

And this concludes my First Blog at Fluxcapacity…cheers to that!

The Woman Who Can’t Forget

Posted by vikas on Jun 10th, 2008

A few weeks ago on 20/20 I came across the amazing story of a woman named Jill Price who remembers every detail of every day of her life. I don't really watch 20/20 that often but I like to check in every once in a while to make sure John Stossel is still rocking the mustache.

Jill's extremely rare condition is called hyperthymesia. Given any date after 1980, she can describe almost every detail of what happened that day from her point of view. This includes things that most people forget a few days later like the weather, what was on television, and what she had for lunch. Remarkably, this condition doesn't seem to have negatively affected her other thinking abilities in a significant way.

I found it interesting that she said her ability is both a gift and a curse. Her memories can be automatically triggered by any of her senses - a smell, a song, a name. Because of this lack of control, she often has to relive horrible memories along with the good ones. She describes her memories as a picture in picture that's always playing. So if something triggers a memory of a loved one dying, she is forced to experience it along with all the emotions she felt at the time. They showed photos of her over time, and it is clear that the condition has taken a toll on her.

Diane Sawyer of 20/20 asked Jill many questions like, "what happened on January 17th, 1983" and Jill was able to answer every time. Incredibly, one of the books that was used to question Jill actually had a mistake that she was able to catch.

All of the questions, however, were based on date and time. On the show Jill was never asked questions like, "when was the last time you were in Chicago?" or "who was the first person you met in college?" If she can only answer questions based on date and time, then it would seem to imply that while the temporal "index" of her brain was accessible to her in a controlled manner, she can't use other "indexes" based on location or her senses in the same way. I would love to ask her some questions to find out if this is the case. Also, I'd like to find out what happens if she is experiencing something incredibly happy in the present, and then a bad memory is triggered. What effects her more, the past or the present?

It's a fascinating case, and scientists are apparently learning a lot about our brain and memory because of her and others with the same condition.

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