Monthly Archives: December 2006

Indian Fine Art Photographers

For someone living in the Google age, it’s slow business finding information about Indian phtographers. Thanks to the small number of people who pointed me to a few photographers of note, I got a modest start. But very modest. (Mostly just Raghubir Singh and Prashant Panjiar.)

So I’ve decided to try a different track for a while, searching for and sending queries to various galleries in India. No responses yet — no doubt it got stuck in some spam filter or another. But at the Cymroza Gallery I found a few more names:

  • Bhalu Mondhe
  • Sabrina and Moutushi

And Wikipedia has a smallish list of Indian photographers, including

  • Darogha Ubbas Alli
  • F. W. Champion
  • Lala Deen Dayal
  • Victor George
  • Atul Kasbekar
  • Madhaviah Krishnan
  • Raghu Rai
  • B. S. Ranga
  • Sandip Ray
  • Sukumar Ray
  • Sooni Taraporevala

Still . . . more foreigners publishing images of India than Indians themselves.

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Ruth Bernhard (1905-2006)

To say that Ruth Bernhard spent a life in photography would sell short the span of her life and the impact of her work. It’s fairer to say that she spent two or three lives in photography.

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Expanded Blogroll

If you read these entries via RSS newsfeeds, you might not have noticed a couple of new features. In particular, there are many more links to other photography weblogs. So, come inside and see what’s new.

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The MathWorks Mathemagic Mathstravaganza Mathpetition

As seen in the Brown Daily Herald.

But seriously . . . There was no trip to Vegas for the winner of the latest MATLAB Programming Contest. Just lots of “cool” prizes and the adoration of engineers everywhere.

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“What did I miss?” (part 1)

I’m a voracious link clicker . . . and pack rat. (I click and I click and sometimes I even read.) Here’s the first in a series highlighting what I would have clicked over the last couple of months (and probably read) if I hadn’t been taking classes:

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My Testing Penance

Earlier this summer I sent an unintentionally impolitic e-mail to a rather large distribution list, of course. In it I criticized a proposed software test plan and unfortunately went on to insult someone connected to the project.

It appears that Fortuna (or whatever metes out my karma’s due) has a sense of humor. My penance came in the form of the final project for my Software Testing Techniques course: a full software test plan. Thank g-d that’s done.

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Leonard Freed (1929-2006)

One of my favorite documentary images from the 1970′s is Leonard Freed’s photograph of a police officer playing a game with kids in New York. (From Garrison Art Center.)

More images…

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Software testing redux

I’m almost free. . . . The final testing project for my software testing techniques course is all that I have left. I can’t wait to finish it. I will soon be able to read the paper, read a book, go photographing, and everything else without thinking that I should be studying.

Without getting into it too much, I’m a little disappointed with the course. I have learned a bit — especially that it really is not possible to completely test software — but I do wish that it didn’t feel straight out of 1990. I wish the course were more about (you know) testing techniques. Oh, and what’s with the 100-question true/false final exam that lifts statements striaght from obscure parts of the book?

What are the big things that I did learn? Primarily, The MathWorks does testing very well. We have detailed test plans that say what’s going to be tested, what the expected output is for given inputs, and so on. We set targets for code coverage. We keep metrics about defects bugs. We have extensive sets of automated regression tests that enable continuous integration. Our testers work with the developers in every phase of the development lifecycle. In fact, our developers and testers usually have collaborative rather than combative relationships. We have a clear, rational way of classifying the importance of bugs. . . . We’re not perfect, but we try hard.

Believe it or not, for the overwhelming majority of my 13-person class most of those statements don’t apply. In general, software quality assurance is the red-headed stepchild of the development organization. Companies, especially small ones, just don’t want to spend money on testing. The authors of the textbook seem to accept this as an immutable fact of testing. QA is a “low-level department” in organizations that have hierarchical, top-down decision-making processes. By saying that an essential part of doing testing well is to avoid other people’s insecurities and issues, the book is premised on corporate dysfunction and disenfranchised employees. But, the authors do seem to be describing the real world my colleagues experience.

So what did I learn that I can apply?

  • The purpose of testing is to find bugs and get them fixed. So focus on testing that finds defects.
  • Try to find the most serious defects first.
  • Testing should start with requirements analysis — requirements are often poorly specified or impossible to implement.
  • Unit testing (and test-driven development) is very important but isn’t software testing.
  • Focusing on code coverage — especially condition coverage — is important but can’t find all latent defects (such as dividing by zero).
  • Blackbox testing — where you don’t assume you know anything about the code — is touted as the best way to find latent errors.
  • Think of ways that software could fail and work backwards toward test cases.
  • Focus on equivalence classes and boundary tests. Don’t forget state transitions, especially for GUIs.

Fun fact (that may be out of date): Software bugs cost 0.6% of GDP, or roughly $60 billion/year. One-third of this might have been saved by better testing.

UPDATE: Cem Kaner, one of the authors of the course text, admits that some of the ideas are out-of-date. A new version of the book is in the works. Apparently, “it is not the primary purpose of testing to find bugs.” Damn! I thought I knew what was important.

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Lisa the Innumerate called a few minutes ago to ask about affine transformations, so I figure there must be some general interest among my readers for more math. (For the uninitiated an affine transformation in 2D is essentially a particular kind of geometric operation that preserves parallel lines and proportions.)

Jeff Atwood at Coding Horror wrote a pretty good article comparing pseudo-random number generators. So what’s the difference between randomness and merely “pseudo-randomness?” I remember Prof. Goldberg in the Philosophy Department at Grinnell asking me this a decade ago. Naturally, I had no idea. So I went to Knuth.

Simply, a true random sequence is most tersely described by listing the entire sequence. That is, there is no algorithm for producing the next number from any of the preceeding numbers. That kind of randomness has been difficult for both computers and people to approach. (In fact, computer science has the concept of “oracles,” mythical black box operations that give answers in completely inscrutable ways, in order to cope with this kind of difficulty.)

Pseudo-randomness, uses an algorithm to produce a set of numbers that appears random — but of course it can’t be because it’s generated by a rule. If you know a small number of the beginning numbers and the algorithm itself, you can determine all of the rest of the numbers. (In which case you can always beat the computer at rock-paper-scissors or break codes or whatever.) A good pseudo-random number generator has two very important parts: (1) an algorithm capable of producing a large set of nonrepeating numbers, and (2) a seed generator that picks the initial values for the algorithm. Without a good seed the algorithm produces the same numbers over and over.

Seed generation is often quite clever and interesting. All good magic tricks oracles are.

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The NSA Museum in Pictures

A secret trip to Maryland.

Shh… They served, but they served in silence.
Send Books Thinking Machine
Welcome to the Terabytes Dimes from heaven
Bad Guys that look like us Always wear sensible shoes for signals work
Black helicopters airplanes My ticket to Gitmo
“I am SpartacusTiger Woods … Military Intelligence”    
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