Forgot your password?

Comment: Re:Older workers cost more. (Score 1) 365

by Robb (#43588405) Attached to: Can Older Software Developers Still Learn New Tricks?
I still see plenty of O^3 algorithms when there is a fairly obvious O^2 or even linear one. These are cases where they aren't even thinking about complexity they just wrote down the first algorithm that seemed to work. The single biggest issue I have with younger programmers is the lack of deliberate design; they are just focused on getting something that seems to work without recognizing or even thinking much about the consequences of their decisions.

Comment: Swissmetro was a similar idea (Score 1) 625

by Robb (#40628623) Attached to: Why Ultra-Efficient 4,000 mph Vacuum-Tube Trains Aren't Being Built
There were quite a few studies about the feasibility of doing something like this in Switzerland although the top speed they were looking at was about 500 kph and they wanted to connect the major Swiss cities so it would be about 15 minutes from one city to the next. It would require such a huge investment that really only the government could do it and even though it appears to make longterm financial sense there isn't enough political support to start the ball rolling.

Comment: I don't think it means what you think it means (Score 1) 633

by Robb (#37880686) Attached to: When Having the US Debt Paid Off Was a Problem
In 2010, 865 billion was paid into social security and 701 billion was paid out. So ignoring social security and interest on the debt we have 4 major categories of spending, DoD, Medicare & Medicaid, Mandatory and Discretionary. About 150 billion of the discretionary spending is military so we end up with something like Defense: 839 billion, Medicare & Medicaid: 793 billion, Mandatory: 416 billion and Discretionary (non-defense): 510 billion. I don't think "pale in comparison" means what you think it means.

Comment: Re:Missing the point of math... (Score 1) 636

by Robb (#35790614) Attached to: Are Graphical Calculators Pointless?

But it's not taught that way.

It's never taught that way in US schools. Ever. It's always taught as an abstraction without ever tying any of it to real life. Ever. (repetition for emphasis)

It is taught that way if you have a good teacher. All my math teachers were excellent so we got lots of practical examples. But just like any skill, there is a lot of what one of my math teachers called "crank and grind" that you have to go through to internalize the skill enough that you can then focus on applying it.

Comment: By far the biggest issue I see is ... (Score 1) 396

by Robb (#31211074) Attached to: What Knowledge Gaps Do Self-Taught Programmers Generally Have?
Many self-taught programmers lack even a basic understanding of algorithmic complexity. This is the single biggest issue I run into in industry and should be one that isn't too hard to fix. Again and again I find people have written some algorithm that just doesn't scale to larger amounts of data because it is n^3 or n^4 instead of linear. After that I would say it is a good grasp of some of the ideas in functional programming particularly recursion. There are a lot of other things I run into but I never noticed that self-taught programmers were more prone to them than others.

Antimatter In Lightning 169

Posted by Soulskill
from the doc-brown-can-now-power-his-warp-drive dept.
AMESN writes "The Fermi Gamma-ray Space Telescope, launched last year, detects gamma rays from light years away, but recently it detected gamma rays from lightning on Earth. And the energy of the gamma rays is specific to the decay of positrons, which are the antimatter flavor of electrons. Finding antimatter in lightning surprised researchers and suggests the electric field of the lightning somehow got reversed."

Comment: Re:The Amiga Hand? (Score 1) 517

by Robb (#29052057) Attached to: World's First Formally-Proven OS Kernel
The methodology is the best you can do; proving anything is basically establishing that two descriptions are equivalent.

With formal systems you usually have one definition that written to make it obviously correct and another that is more "pragmatic". In the case of propositional logic the obviously correct formalization is truth tables which are completely untractable to work with for large numbers of variables but are very simple conceptually. The "pragmatic" formalization is the logical connectives like and, or, implication etc that we normally think of as propositional logic. When they prove that propositional logic is sound they mean that all propositions give the same result as a truth table when evaluated and when they prove it is complete they mean that all truth tables give the same result as a proposition and thus propositional logic and truth tables both formalize the same concept.

There is no concept of "correct" in formal systems because it is inherently an informal concept meaning it does what it is supposed to do.

"Don't discount flying pigs before you have good air defense." -- jvh@clinet.FI