Beta

Slashdot: News for Nerds

×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Comments

top

Ikaros Spacecraft Successfully Propelled In Space

GileadGreene Re:Top Speed ? (229 comments)

Also, maneuverability, as I just don't see most of those sailing techniques working in a vacuum.

Solar sails don't, and have never been intended to, use "sailing techniques". In that sense "solar sail" is an unfortunate misnomer. Solar sail maneuvers typically take advantage of the fact that changing the sail orientation enable you to direct the resultant force from the solar radiation pressure either along or counter to the orbital velocity vector. Depending on which way you point the sail you either increase or decrease your orbit energy. Increases in orbit energy correspond to increases in orbit radius (or semi-major axis if in a non-circular orbit), while decreases in energy decrease the radius of the orbit. There's no "tacking" in the sense of ocean sailing.

about 4 years ago
top

Ikaros Spacecraft Successfully Propelled In Space

GileadGreene Re:Its a good start (229 comments)

The problem is that bleeding off energy with a solar sail isn't like just jumping onto a sunward elliptical orbit. You're likely to spiral in towards the sun, rather than zip around it. More importantly, a "slingshot" takes advantage of planetary motion relative to the sun to achieve a large trajectory change: a "slingshot" around the sun won't do anything except get you onto the outbound leg of the trajectory you're already on (i.e. it won't help you get further out from the sun than you were already going anyway). You'd probably be better off conserving the energy you already have, and using the sail to spiral out into a higher orbit.

about 4 years ago
top

What the Top US Companies Pay In Taxes

GileadGreene Re:If I could do it, I would! (658 comments)

Corporate CEOs are no friends of the free market...

Of course they're not. They wouldn't exist in an actual free market. Corporations themselves exist as the result of government interference in the free market, by way of laws that allow corporations to exist, to have legal rights that permit them to make transactions in the market, and to limit the liability of the owners. Corporate CEOs who lobby the government are simply trying to tweak the government's distortion of the regulated market even further in their favor.

more than 4 years ago
top

The Duct Tape Programmer

GileadGreene Re:So, does the Duct Tape Programmer... (551 comments)

Ruby and Python have only been "mainstream" for a few years, while static languages have been around since the ancient days.

Right. But Lisp, which is dynamically typed, has been around since the late 50s (second oldest high level language). And Smalltalk, which was a strong influence on Ruby, dates from the early 70s. Erlang has been around since the mid 80s. So "dynamic" languages have been around since the ancient days too. There's a place for both in the modern development environment. Horses for courses.

Some would argue that dynamic/duck + extra testing has the same effect with less cost than static + less testing.

Indeed. Others would argue that (good) static + more testing gives you the best of both worlds. This is a time-worn debate, and is unlikely to be resolved any time soon. Ultimately, the choice will come down to a combination of developer preference, and the cost/benefit/reliability issues associated with the specific domain you're working in. The biggest problem with debates like the static/dynamic one is that everyone seems to assume that the way software is developed in their specific application domain is suitable for every other application domain too. In practice, that's hardly ever true.

more than 4 years ago
top

Nine Words From Science Which Originated In Science Fiction

GileadGreene Re:Forgot to mention (433 comments)

Er... Snow Crash was first published in around 1992. Some 8 years after Neuromancer. So I fail to see how Stephenson could be a "predecessor" of Gibson.

more than 5 years ago
top

Ballmer Scorns Apple As a $500 Logo

GileadGreene Re:Paying $500 for an OS that works, however... (1147 comments)

It's more than just quality hardware and a good OS though. What you're getting when you buy an Apple product is a well-designed system. Aristotle said that "the whole is greater than the sum of its parts", and he's right in the sense that the quality of the whole depends on how the parts are combined and how they interact with each other. That's the bit that Ballmer doesn't seem to get. MS sells some of the parts. Apple sells the whole. Apple as a company may have some warts. It's products are not always perfect. But they, more than most companies, strive to develop good systems that do what the end-user needs, instead of just good parts that need to be fitted into a whole by the end-user. That's part of what makes Apple fans so loyal to the brand.

more than 5 years ago
top

Ballmer Scorns Apple As a $500 Logo

GileadGreene Re:It seems ironic... (1147 comments)

I found much the same thing when shopping around for laptops back in 2004. Compare like-for-like, and suddenly that Powerbook didn't seem as expensive after all.

more than 5 years ago
top

Mathematics Reading List For High School Students?

GileadGreene Concepts of Modern Mathematics (630 comments)

You might try Ian Stewart's Concepts of Modern Mathematics. Quoting from the end of the book:

The reader who has persevered this far must by now be a cultivator of mathematics, even if he was not at the start of the endeavour. He will therefore appreciate that, while it may be ancient and venerable, it is far from complete; that not all of it is dry; and that its reasoning has not always been either unambiguous or irrefutable - nor is it yet.

Which really captures what the book is about. It's an extremely accessible introduction to abstract algebra, topology, probability, and several other topics. It does a great job of presenting the overall structure of mathematics, and giving just enough of an idea of what's going on to make you want to learn more, without being dry, boring, or bogged down in details. I found it quite an inspiring book, and several friends that I lent it to found the same. Judging from the Amazon reviews, we weren't the only ones. All that, plus it's available as a low-cost Dover book :-)

more than 5 years ago
top

Global Warming Irreversible, NOAA Scientist Finds

GileadGreene Re:Wars and disease will do us in. (1061 comments)

Yeah...uh...that might be the "overshoot and collapse" that the Limits to Growth report seems to indicate we can expect some time in the mid to late 21st century.

more than 5 years ago
top

Global Warming Irreversible, NOAA Scientist Finds

GileadGreene Re:Barbra Streisand (1061 comments)

That was not what they were teaching in schools 20 years ago. Oil was supposed to have run out about 1997 or 1998 and tin 1990ish.

Regardless of what you were taught in school 20 years ago, that's not what the actual Limits to Growth report said. There was a lot of bogus information propagated about the Limits to Growth report at the time it came out, largely by people who didn't like what it actually had to say. The reality is that the Limits to Growth report explored a number of different possible scenarios (varying assumptions such as the impact of technological change and of social policies), and found that most (but not all) scenarios seem to lead to some kind of "overshoot and collapse" in the mid to late 21st century. These were never meant to be precise predictions, but rather to provide some idea of the global system's behavioral tendencies. Interestingly, a recent study has found that the Limits to Growth "standard run" scenario tracks quite well with the actual observed behavior of the world over the last 30 years. As the abstract of that report says:

Contrary to popular belief, The Limits to Growth scenarios by the team of analysts from the Massachusetts Institute of Technology did not predict world collapse by the end of the 20th Century. This paper focuses on a comparison of recently collated historical data for 1970-2000 with scenarios presented in the Limits to Growth. The analysis shows that 30 years of historical data compares favorably with key features of a business-as-usual scenario called the "standard run" scenario, which results in collapse of the global system midway through the 21st Century. The data does not compare well with other scenarios involving comprehensive use of technology or stabilizing behaviour and policies.

more than 5 years ago
top

Senator Prods Microsoft On H-1B Visas After Layoff Plans

GileadGreene Re:Republican? (574 comments)

Sure, I suppose "the People" have the right to control who enters "their" country. But if they exercise that right, they are imposing artificial constraints on the labor market, making the overall economic system something other than "free".

more than 5 years ago
top

Senator Prods Microsoft On H-1B Visas After Layoff Plans

GileadGreene Re:Republican? (574 comments)

In a truly free market, government and Microsoft would not talk to each other at all. Microsoft would have to deal with its labor shortages in a different manner (perhaps hire some U.S. engineers w/o jobs, instead of willfully ignoring them).

In a truly free market, the government wouldn't apply any restrictions to the flow of goods or workers into and out of the country. There'd be no need for MS to beg for H1Bs because the government wouldn't be preventing workers from other countries entering the US in the first place. What you're describing as "truly free" is simply a different set of restrictions than the current ones.

more than 5 years ago
top

Obama Transition Team Examining Space Solar Power

GileadGreene Re:Why bother with space solar power? (275 comments)

Actually, the sun does set in GEO. Just not for very long, and only at certain times of the year. Eclipse seasons for a geostationary satellite occur around the vernal and autumnal equinoxes. The seasons last around 40-50 days, with maximum sun-occultation duration of about 72 minutes. A discussion of the relevant orbit geometry can be found here.

more than 5 years ago
top

Is UML Really Dead, Or Only Cataleptic?

GileadGreene Re:UML great for design (156 comments)

To me, a prototype is a small-scale implementation (potentially with reduced functionality) intended to prove out a concept. The prototype may do less, but it's developed at the same level of abstraction as the final implementation. In contrast, a model is an abstracted idealization of the final implementation (i.e. developed at a higher level of abstraction than the implementation). Of course, there's a lot of room for interpretation in those definitions. The difference between prototyping and modeling isn't quite so clean-cut in the world of software as it is in engineering domains that build physical systems. So it's entirely possible that you may view models as a kind of prototype (or perhaps prototypes as a kind of model).

more than 6 years ago

Submissions

top

GileadGreene GileadGreene writes  |  more than 7 years ago

GileadGreene (539584) writes "Test-Driven Development is widely accepted as practice that can lead to better software that's more likely to meet its requirements. Some people like to talk about test suites as "executable specifications", and the recent buzz about Behavior-Driven Development largely seems to be about making tests focus more on specification rather than implementation details. The logical progression is to what might be termed Specification-Driven Development, in which formal verification techniques such as extended static-checkers and theorem-provers are combined with design-by-contract tools and test-driven development to provide much more comprehensive validation and verification suites. Shades of this approach can be seen in MS Research's Spec# project, as well as some of the work by the JML and ESC/Java2 teams. Meanwhile, the ESpec project at York University is developing tools that will allow developers to write testable specifications at all stages of software development process, and create specification items such as unit tests, contracts and acceptance tests as early as possible. Will the momentum surrounding TDD and BDD allow Specification-Driven Development to gain acceptance with the wider developer community? Will the use of more rigorous analyses during software development finally allow software engineering to gain broad acceptance as a "real" engineering discipline?"

Journals

GileadGreene has no journal entries.

Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Create a Slashdot Account

Loading...