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Comment: Re:Not just version 4.9 (Score 1) 669

by Immerman (#47549985) Attached to: Linus Torvalds: "GCC 4.9.0 Seems To Be Terminally Broken"

But it's not. The language specification sets semi-deterministic rules for how the code must be converted to machine code. In this case the compiler was overstepping those bounds and generating machine code inconsistent with the source code and translation rules. Very inconsistent actually, given that the compiler was also ignoring the flags that imposed more stringent requirements on the translation than those in the language specification itself.

Comment: Re:Or upgrade to llvm ... (Score 1) 669

by Immerman (#47549863) Attached to: Linus Torvalds: "GCC 4.9.0 Seems To Be Terminally Broken"

Only for the 1% of your code that is the largest bottleneck, and even then a good modern compiler fed high-level source written with compiler optimizations in mind can often generate machine code that's as good or better than competent hand-coded ASM, due in part to the fact that it need not care about readability, maintainability, etc. Meanwhile assembly requires considerably more developer time to maintain than high-level source.

Good rule of thumb: stay away from assembly unless you've already:
- had a profiler pinpoint the code as a bottleneck area
- written the code with an eye towards being particularly compiler-optimzation friendly
- analyzed the compiler output and found significant bottlenecks that could be optimized away by hand, and aren't caused by sub-par input source
It's a pretty rare chunk of code that can make it past all three filters to be potentially worth rewriting in assembly. And those filters don't even consider the significant maintainability losses you typically get by introducing assembly.

Comment: Re: I know you're trying to be funny, but... (Score 1) 669

by Immerman (#47549731) Attached to: Linus Torvalds: "GCC 4.9.0 Seems To Be Terminally Broken"

So, he should cater to the personalities of the people that might theoretically contribute in the future, rather than to the personalities of those who have proven themselves by contributing for years or decades? Doesn't sound particularly effective to me. Perhaps it might be worth considering if the community were suffering from a shortage of contributors, but as far as I'm aware that hasn't been the case in decades.

Meanwhile, my sense is that Linus mostly only pulls out the abusive language in the face of gross incompetence - such as situations like this where major bugs make it into the release versions of critical infrastructure.

Comment: Re:no problem (Score 1) 310

round != perfectly circular, and the Earth is a hell of a lot rounder than any circle you can draw by hand.

And if you're a pedant going with the mathematical definition of circle, then there isn't much at all in the universe that qualifies. Planetary orbits are probably about the closest approximations there are to a "perfect" ellipse, and the gravitational pertubations of other planets make sure they're far from perfect.

Comment: Re:Not news (Score 1) 310

The Americas were pretty ecologically lush when the Europeans first arrived, despite being pretty thoroughly settled for 5-10,000 years at that point. In fact the population was so dense that the journals of early European explorers report that the smoke from their cook fires was visible for a week before the land itself came into view. Now, a scarce 500 years later, the vast hardwood forests have been exterminated and the great plains have expanded from the Mississippi all the way to the Appalachians and are gradually turning into desert.

There's something to be said for actually paying attention to the ecosystem around you and considering the long-term consequences of your actions. from Wikipedia

"In every deliberation, we must consider the impact on the seventh generation... even if it requires having skin as thick as the bark of a pine." This is an often repeated saying, and most who use it claim that it comes from “The Constitution of the Iroquois Nations: The Great Binding Law.”

We might have been better off if we had incorporated a bit more of their constitution into our own.

Comment: Take care of your yard? (Score 4, Interesting) 310

I imagine it's closer to "Invasive species are a danger to the entire ecosystem, including, eventually, themselves." When dealing with such the usual solutions are extermination (generally ineffective), or introducing a predator capable of keeping them in check without further destabilizing the ecosystem. Assuming we wish to do neither, nor suffer global ecosystem collapse, it would behoove us to start learning to co-exist with our ecosystem rather than strip-mining it.

And it's not like that is some sort of knee-jerk hippie "let's all live in mud huts" bullshit. As one example consider the gradually increasing numbers of oceanic "wildlife preserves" where all fishing and other destructive exploitation is banned - Not only does the protected area begin returning to pre-exploitation lushness, but so do the surrounding waters. Fishing yields around the protected zone reverse the global trend and begin to increase dramatically, greatly benefiting even the fishermen who were initially opposed to banning fishing in the richest waters. Given half a chance nature can be extremely bountiful, we just need to give the ecosystems a chance to stay healthy rather than maximizing short-term profits at the expense of long-term desertification.

Comment: Re:no problem (Score 5, Interesting) 310

Very true. A few years ago I was tutoring at a community college and actually met a man who didn't realize the Earth went around the sun. At first I assumed he was pulling my leg, how could an American in this day an age not know that?!? But he was fascinated by the idea, and we had a long conversation about the basics of orbital mechanics and how they shape tides, the seasons, etc.

Comment: Re:Correction (Score 1) 97

by Immerman (#47531835) Attached to: UEA Research Shows Oceans Vital For Possibility of Alien Life

I reserve my opinion on the number of gods until I see evidence for or against their existence. Certainly many have possessed metaphorical existence, with their priests wielding massive sociological powers in their name, and I have seen enough first-hand evidence of intentional phenomena that stretch the limits of plausibility that I'm willing to entertain the possibility that it might be possible that at least some manner of beings capable of discretely playing the part exist. (Ever read American Gods by Neil Gaiman? A rather amusing take on the possibility that gods exist, and were created by man) Personally though I lean more towards the Tao - I've seen plenty of direct evidence for that, and am still not sure whether it's an actual "thing" or just a very apt metaphorical construct to describe the synergies in a chaotic system. Or even whether there's any meaningful distinction between the two positions.

Comment: Re:Slingshot? (Score 2) 44

by Immerman (#47531681) Attached to: Comet To Make Close Call With Mars

I think comets tend to be moving far to fast for a gravitational slingshot to have much effect. Your basic gravitational slingsot involves a near-miss head-on collision with a planet racing towards you. You whip around the planet and fly back roughly the way you came with your initial speed plus the orbital speed of the planet. Obviously you can do a less dramatic maneuver, but you only get a fraction of the speed boost.

Comets meanwhile have typically been falling towards the sun from a good portion of a light year away, and are moving far, *far* faster than the planets, so even an ideal slingshot maneuver wouldn't alter their speed much, relatively speaking. At most their path gets deflected so that they leave the inner system with a very different trajectory than they entered with, rather than heading back out pretty much the way they came, essentially rotating the major axis of their orbit. But their orbital energy, and hence the basic shape of their orbit, remains largely unchanged. Unless of course it hits something, but that's a matter of hitting one of a few dust motes in an Olympic stadium, and is highly unlikely for any given comet.

In the case of periodic comets (those whose highly elliptical orbits will eventually bring them back into the inner system) you can have cumulative effects, especially if it happens to have an orbital resonance with one of the planets. And over the course of several orbits it's possible for gravitational effects to "fine tune" it's path in ways that increase the odds of a collision. But I believe this comet is on a parabolic path rather than an elliptical one (considerably higher orbital energy), so unless it hits something on this pass (or evaporates) it will slingshot around the sun and then depart to interstellar space, never to be seen again.

Comment: Re:Too bad this didn't happen in 50 years (Score 1) 44

by Immerman (#47531463) Attached to: Comet To Make Close Call With Mars

Sure we do - Solar, wind, nuclear, etc. are all perfectly viable energy sources, they're just currently more expensive than fossil fuels (especially when you factor in battery costs) so market forces have continued to favor those. Prices continue to fall though, and now we have Aquion selling batteries for 1/10th the amortized cost of lead-acid for stationary applications, which will ti the scale even further. And if we stopped publicly funding the various tax-breaks, subsidies, environmental damage immunities, and wars of corporate convenience that are propping up the fossil fuel industry we'd see renewables suddenly take a huge leap forward.

And if you're afraid of the sudden surge in energy prices, take all those public funds saved and distribute them to consumers instead so that they can afford the increased prices. Make oil compete on a level playing field and it really isn't all that attractive anymore as an energy source. Meanwhile as a lubricant we already have far superior synthetics, and we could live without plastic.

Comment: Re:Too bad this didn't happen in 50 years (Score 1) 44

by Immerman (#47531321) Attached to: Comet To Make Close Call With Mars

Not necessarily - Venus has no geomagnetic shielding either, and gets hit by a far denser solar wind. In fairness it's thick ionosphere interacts with the solar wind to generate an induced magnetosphere, but such a thing could potentially be engineered elsewhere.

Plus, even without a magnetosphere we're talking about a process that takes thousands, maybe even millions of years to strip a planet of it's atmosphere - if we can build it up in the first place we should be able to compensate for the losses easily enough. Hell, Mars *still* has an atmosphere, even if it is pretty thin these days.

Anyone can do any amount of work provided it isn't the work he is supposed to be doing at the moment. -- Robert Benchley

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