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Contact info diagram

My contact information arranged into a diagram:

Yesterday at SciPy 2015 Allen Downey did something similar for his contact info and gave me the idea for the image above.

LinkedIn doesn’t quite fit; you have to know that LinkedIn profiles stick linkedin.com/in/ before the user name.

No, I’m not a bot.

Periodically someone on Twitter will suggest that one of my Twitter accounts is a bot. Others will reply in the second person plural, suggesting that there’s a group of people behind one of the accounts. These accounts aren’t run by a bot or a committee, just me.

I do use software to schedule my tweets in advance. Most of the tweets from my personal account are live. Most of the tweets from my topic accounts are scheduled, though some are live. All replies are manual, not automated, and I don’t scrape content from anywhere.

Occasionally I read the responses to these accounts and sometimes I reply. But with over half a million followers (total, not unique) I don’t try to keep up with all the responses. If you’d like to contact me, you can do so here. That I do keep up with.

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The Nickel Tour

If you’re new to this blog, welcome! Let me show you around.

Here are some of the most popular posts on this site and some other things I’ve written.

If you’d like to subscribe to this site you can do so by RSS or email. I also have a monthly newsletter.

You can find out more about me and my background here.

You can also find me on Twitter and Google+.

If you have any questions or comments, here’s my contact info.

AI Spring

Artificial intelligence, or at least the perception of artificial intelligence, has gone from disappointing to frightening in the blink of an eye. As Marc Andreessen said on Twitter this morning:

AI: From “It’s so horrible how little progress has been made” to “It’s so horrible how much progress has been made” in one step.

When I read this I thought of Pandora (the mythical figure, not the music service).

“Are you still working on opening that box? Any progress?”

“No, the lid just … won’t … budge … Oh wait, I think I got it.”

 

Related post: Why the robots aren’t coming in the way you expect by Mark Burgess

Ursula K. Le Guin has it backward

Ursula K. Le Guin is asking people to not buy books from Amazon because they market bestsellers, the literary equivalent of junk food. She said last week

I believe that reading only packaged microwavable fiction ruins the taste, destabilizes the moral blood pressure, and makes the mind obese.

I agree with that. That’s why I shop at Amazon.

If I liked to read best-selling junk food, I could find it at any bookstore. But I like to read less popular books, books I can only find from online retailers like Amazon. If fact, most of Amazon’s revenue comes from obscure books, not bestsellers.

Suppose I want to read something by, I don’t know, say, Ursula K. Le Guin. I doubt I could find a copy of any of her books, certainly not her less popular books, within 20 miles of my house, and I live in the 4th largest city in the US. There’s nothing by her in the closest Barnes and Noble. But I could easy find anything she’s ever written on Amazon.

If you’d like to support Amazon so they can continue to bring us fine authors like Ursula K. Le Guin, authors you can’t find in stores that mostly sell packaged microwavable fiction, you can buy one of the books mentioned on this blog from Amazon.

Reading equations forward and backward

There is no logical difference between writing A = B and writing B = A, but there is a psychological difference.

Equations are typically applied left to right. When you write A = B you imply that it may be useful to replace A with B. This is helpful to keep in mind when learning something new: the order in which an equation is written gives a hint as to how it may be applied. However, this way of thinking can also be a limitation. Clever applications often come from realizing that you can apply an equation in the opposite of the usual direction.

For example, Euler’s reflection formula says

Γ(z) Γ(1-z) = π / sin(πz).

Reading from left to right, this says that two unfamiliar/difficult things, values of the Gamma function, are related to a more familiar/simple thing, the sine function. It would be odd to look at this formula and say “Great! Now I can compute sines if I just know values of the Gamma function.” Instead, the usual reaction would be “Great! Now I can relate the value of Gamma at two different places by using sines.”

When we see Einstein’s equation

E = mc2

the first time, we think about creating energy from matter, such as the mass lost in nuclear fission. This applies the formula from left to right, relating what we want to know, an amount of energy, to what we do know, an amount of mass. But you could also read the equation from right to left, calculating the amount of energy, say in an accelerator, necessary to create a particle of a given mass.

Calculus textbooks typically have a list of equations, either inside the covers or in an appendix, that relate an integral on the left to a function or number on the right. This makes sense because calculus students compute integrals. But mathematicians often apply these equations in the opposite direction, replacing a number or function with an integral. To a calculus student this is madness: why replace a familiar thing with a scary thing? But integrals aren’t scary to mathematicians. Expressing a function as an integral is often progress. Properties of a function may be easier to see in integral form. Also, the integral may lend itself to some computational technique, such as reversing the order of integration in a double integral, or reversing the order to taking a limit and an integral.

Calculus textbooks also have lists of equations involving infinite sums, the summation always being on the left. Calculus students want to replace the scary thing, the infinite sum, with the familiar thing, the expression on the right. Generating functions turn this around, wanting to replace things with infinite sums. Again this would seem crazy to a calculus student, but it’s a powerful problem solving technique.

Differential equation students solve differential equations. They want to replace what they find scary, a differential equation, with something more familiar, a function that satisfies the differential equation. But mathematicians sometimes want to replace a function with a differential equation that it satisfies. This is common, for example, in studying special functions. Classical orthogonal polynomials satisfy 2nd order differential equations, and the differential equation takes a different form for different families of orthogonal polynomials. Why would you want to take something as tangible and familiar as a polynomial, something you might study as a sophomore in high school, and replace it with something as abstract and mysterious as a differential equation, something you might study as a sophomore in college? Because some properties, properties that you would not have cared about in high school, are more clearly seen via the differential equations.

Data, code, and regulation

Data is code and code is data. The distinction between software (“code”) and input (“data”) is blurry at best, arbitrary at worst. And this distinction, or lack thereof, has interesting implications for regulation.

In some contexts software is regulated but data is not, or at least software comes under different regulations than data. For example, maybe you have to maintain test records for software but not for data.

Suppose as part of some project you need to search for files containing the word “apple” and you use the command line utility grep. The text “apple” is data, input to the grep program. Since grep is a widely used third party tool, it doesn’t have to be validated, and you haven’t written any code.

Next you need to search for “apple” and “Apple” and so you search on the regular expression “[aA]pple” rather than a plain string. Now is the regular expression “[aA]pple” code? It’s at least a tiny step in the direction of code.

What about more complicated regular expressions? Regular expressions are equivalent to deterministic finite automata, which sure seem like code. And that’s only regular expressions as originally defined. The term “regular expression” has come to mean more expressive patterns.  Perl regular expressions can even contain arbitrary Perl code.

In practice we can agree that certain things are “code” and others are “data,” but there are gray areas where people could sincerely disagree. And someone wanting to be argumentative could stretch this gray zone to include everything. One could argue, for example, that all software is data because it’s input to a compiler or interpreter.

You might say “data is what goes into a database and code is what goes into a compiler.” That’s a reasonable rule of thumb, but databases can store code and programs can store data. Programmers routinely have long discussions about what belongs in a database and what belongs in source code. Throw regulatory considerations into the mix and there could be incentives to push more code into the database or more data into the source code.

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See Slava Akhmechet’s essay The Nature of Lisp for a longer discussion of the duality between code and data.

New monthly newsletter

Thank you for reading my blog. I’m starting a new email newsletter to address two things that readers have mentioned.

Some say they enjoy the blog, but I post more often than they care to keep up with, particularly if they’re only interested in the non-technical posts.

Others have said they’d like to know more about my consulting business. There are some interesting things going on there, but I’d rather not write about them on the blog.

The newsletter will address both of these groups. I’ll highlight a few posts from the blog, some technical and some not, and I’ll say a little about what I’ve been up to.

If you’d like to receive the newsletter, you can sign up here.

I won’t share your email address with anyone and you can unsubscribe at any time.

RSS feeds for Twitter accounts

Twitter once provided RSS feeds for all Twitter accounts. They no longer provide this service. However, third parties can create RSS feeds from the content of Twitter accounts. BazQux has done this for my daily tip accounts, so you can subscribe to any of my accounts via RSS using the feeds linked to below.

If you would like to subscribe to more Twitter accounts via RSS, you could subscribe to the BazQux service and create a custom RSS feed for whatever Twitter, Google+, or Facebook accounts you’d like to follow.

Magicians vs Repairmen

From The World Beyond Your Head:

The appeal of magic is that it promises to render objects plastic to the will without one’s getting too entangled with them. Treated at arm’s length, the object can issue no challenge to the self. … The clearest contrast … that I can think of is the repairman, who must submit himself to the broken washing machine, listen to it with patience, notice its symptoms, and then act accordingly. He cannot treat it abstractly; the kind of agency he exhibits is not at all magical.

Related post: Programming languages and magic

Key fobs and interstellar space

From JPL scientist Rich Terrile:

In everyone’s pocket right now is a computer far more powerful than the one we flew on Voyager, and I don’t mean your cell phone—I mean the key fob that unlocks your car.

These days technology is equated with computer technology. For example, the other day I heard someone talk about bringing chemical engineering and technology together, as if chemical engineering isn’t technology. If technology only means computer technology, then the Voyager probes are very low-tech.

And yet Voyager 1 has left the solar system! (Depending on how you define the solar system.*) It’s the most distant man-made object, about 20 billion kilometers away. It’s still sending back data 38 years after it launched, and is expected to keep doing so for a few more years before its power supply runs too low. Voyager 2 is doing fine as well, though it’s taking longer to leave the solar system. Surely this is a far greater technological achievement than a key fob.

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* Voyager 1 has left the heliosphere, far beyond Pluto, and is said to be in the “interstellar medium.” But it won’t reach the Oort cloud for another 300 years and won’t leave the Oort cloud for 30,000 years.

Source: The Interstellar Age: Inside the Forty-Year Voyager Mission

Mathematical modeling in Milton

In Book VIII of Paradise Lost, the angel Raphael tells Adam what difficulties men will have with astronomy:

Hereafter, when they come to model heaven
And calculate the stars: how they will wield the
The mighty frame, how build, unbuild, contrive
To save appearances, how gird the sphere
With centric and eccentric scribbled o’er,
Cycle and epicycle, orb in orb.

 

Related post Quaternions in Paradise Lost