Month: February 2008

Why programmers cannot be managed

Posted on by John

Interaction design guru Alan Cooper gave a presentation recently entitled An Insurgency of Quality. As part of his talk, he explains why programmers cannot be managed. Traditional management has an industrial age mindset, while software development is a post-industrial craft. That mismatch explains a great deal. For example, industrial workers respect authority, but programmers respect competence.

According to Cooper, the leader of a group of programmers should be a facilitator, not a manager. Johanna Rothman in her interview on the Pragmatic Programmer podcast elaborates on this same view. The manager’s job is to remove obstacles to productivity — acquire resources, provide protection from interruptions and distractions, etc. — rather than to manage in the industrial sense.

Orthogonal polynomials

Posted on by John

This morning I posted some notes on orthogonal polynomials and Gaussian quadrature.

“Orthogonal” just means perpendicular. So how can two polynomials be perpendicular to each other? In geometry, two vectors are perpendicular if and only if their dot product of their coordinates is zero. In more general settings, two things are said to be orthogonal if their inner product (generalization of dot product) is zero. So what was a theorem in basic geometry is taken as a definition in other settings. Typically mathematicians say “orthogonal” rather than “perpendicular.” The basic idea of lines meeting at right angles acts as a reliable guide to intuition in more general settings.

Two polynomials are orthogonal if their inner product is zero. You can define an inner product for two functions by integrating their product, sometimes with a weighting function.

Orthogonal polynomials have remarkable properties that are easy to prove. Last week I posted some notes on Chebyshev polynomials. The notes posted today include Chebyshev polynomials as a special case and focus on the application of orthogonal polynomials to quadrature. (“Quadrature” is just an old-fashioned word for integration, usually applied to numerical integration in one dimension.) It turns out that every class of orthogonal polynomials corresponds to an integration rule.

Honeybee genealogy

Posted on by John

honeybee

Male honeybees are born from unfertilized eggs. Female honeybees are born from fertilized eggs. Therefore males have only a mother, but females have both a mother and a father.

Take a male honeybee and graph his ancestors. Let B(n) be the number of bees at the nth level of the family tree. At the first level of the tree is our male honeybee all by himself, so B(1) = 1. At the next level of our tree is his mother, all by herself, so B(2) = 1.

Pick one of the bees at level n of the tree. If this bee is male, he has a mother at level n+1, and a grandmother and grandfather at level n+2. If this bee is female, she has a mother and father at level n+1, and one grandfather and two grandmothers at level n+2. In either case, the number of grandparents is one more than the number of parents. Therefore B(n) + B(n+1) = B(n+2).

To summarize, B(1) = B(2) = 1, and B(n) + B(n+1) = B(n+2). These are the initial conditions and recurrence relation that define the Fibonacci numbers. Therefore the number of bees at level n of the tree equals F(n), the nth Fibonacci number.

This is a more realistic demonstration of Fibonacci numbers in nature than the oft-repeated rabbit problem.

Enterprising software

Posted on by John

Cyndi Mitchell in a talk from Rails Conf points out how “enterprise” in the phrase “enterprise software” has taken on the opposite of its customary meaning.

If you call a person enterprising, you have in mind someone who takes risks and accomplishes things.  And “Enterprise” has been the name numerous ships, real and fictional, based on the bold, adventurous overtones of the name. But Cyndi Mitchell says when she thinks about enterprise software, the first words that come to mind are bloatware, incompetence, and corruption. I wouldn’t go quite that far, but words like “bureaucratic” and “rigid” would certainly be on my list. In any case, “enterprise” has a completely different connotation in “enterprise software” than in “USS Enterprise.”

Related posts

Introduction to Mac for Windows developers

Posted on by John

Here are a couple podcasts introducing Windows developers to software development on the Macintosh.

Scott Hanselman: What’s it like for Mac Developers, an nterview with Steven Frank

.NET Rocks: Miguel de Icaza and Geoff Norton on Mono, mostly about .NET development on the Mac

Also, there are a lot of Mac-related talks on the GeekCruise podcast. The talks from January 2007 were directed at a general audience new to the Mac.

Hanselman’s podcast talks about some of the cultural difference between Microsoft and Apple customers. For example, Mac users update their OS more often and complain less about OS changes that break software.

How to avoid being outsourced or open sourced

Posted on by John

Kevin Kelly has a post entitled Better than Free that lists eight things people will pay a premium for, even while closely related things are free or cheap:

  • Immediacy
  • Personalization
  • Interpretation
  • Authenticity
  • Accessibility
  • Embodiment
  • Patronage
  • Findability

Daniel Pink has a related list in his book A Whole New Mind. Pink says the skills that will be increasingly valued over time, and difficult to outsource, are:

  • Design
  • Story
  • Symphony
  • Empathy
  • Play
  • Meaning

In The World Is Flat, Thomas Friedman says four kinds of people are “untouchable,” that is, immune to losing their job due to outsourcing. These are people who are

  • Special
  • Specialized
  • Anchored
  • Really adaptable

In Friedman’s terminology, “special” means world-class talent, someone like Michael Jordan or Yo-Yo Ma. Anchored means geographically anchored, like a barber. For most of us, our best options are to be specialized or really adaptable.

How do these three lists fit together? You could see Kelly’s and Pink’s lists as ways to specialize and adapt your product or service per Friedman’s advice.

  • Meet your customer’s emotional needs (design, authenticity, patronage, empathy).
  • Make things convenient (immediacy, accessibility, findability).
  • Bring the pieces together, both literally (personalization, symphony) and figuratively (interpretation, story, meaning).
  • Be human (embodiment, play).

Merry-go-round water pump

Posted on by John

I ran across this on Guy Kawasaki’s blog, what he calls “the cleverest idea I’ve seen in years.” It’s a water pump for developing areas that works by having children play on in. Here’s a video from National Geographic demonstrating the pump. [Video removed]

Chebyshev polynomials

Posted on by John

I posted a four-page set of notes on Chebyshev polynomials on my website this morning. These polynomials have many elegant properties that are simple to prove. They’re also useful in applications.

Mr. Chebyshev may have the honor of the most variant spellings for a mathematician’s name. I believe “Chebyshev” is now standard, but his name has been transliterated from the Russian as Chebychev, Chebyshov, Tchebycheff, Tschebyscheff, etc. His polynomials are denoted Tn(x) based on his initial in one of the older transliterations.

False positives for medical papers

Posted on by John

My previous two posts have been about false research conclusions and false positives in medical tests. The two are closely related.

With medical testing, the prevalence of the disease in the population at large matters greatly when deciding how much credibility to give a positive test result. Clinical studies are similar. The proportion of potential genuine improvements in the class of treatments being tested is an important factor in deciding how credible a conclusion is.

In medical tests and clinical studies,  we’re often given the opposite of what we want to know. We’re given the probability of the evidence given the conclusion, but we want to know the probability of the conclusion given the evidence. These two probabilities may be similar, or they may be very different.

The analogy between false positives in medical testing and false positives in clinical studies is helpful, because the former is easier to understand that the latter. But the problem of false conclusions in clinical studies is more complicated. For one thing, there is no publication bias in medical tests: patients get the results, whether positive or negative. In research, negative results are usually not published.