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If you're suggesting replacing engines, you may have a few misconceptions. The engines are some of the more expensive parts of a rocket, what with needing all kinds of super-alloys and having extremely low production tolerances.

Hi, I'm new to the thread. It seems very relevant to my interests.

This. Engine reuse is the main reason for it. Engine reuse also have precedent, in that it is done on pretty much every mission to space already. SpaceX, a few days before each launch, hoists the rocket up, fuels it, and does a test burn using the engines to ensure none of them explode immediately from manufacturing defects or similar. Rocket engines aren't built to last indefinitely, but of all the SpaceX flights thus far, there has only been a single engine popping; indicating a pretty high tolerance margin. The rocket itself has an absurdly high tolerance margin, as it can complete its mission even after losing multiple engines (in the case where the engine broke, it made it to orbit successfully).

I believe an online guide for building your own liquid fuel rocket engines suggests that even with ordinary materials, you can get a good few hours of burn time out of one.

Edit: Also, the payload was 11 communication satellites for OrbComm.

Quote from: Reelya on December 08, 2015, 09:15:41 pm

Quote from: Dutrius on December 08, 2015, 05:26:48 pm

I can think of a function where recursion is required. The Ackermann function.

100% Required or just preference? In my opinion it's extremely rare to find an algorithm which absolutely cannot be converted between iteration and recursion if you put some effort in.

A quick google shows that it's possible to write a loop version, and I'm pretty sure that the loop version could be optimized faster.
http://stackoverflow.com/questions/10742322/how-to-rewrite-ackermann-function-in-non-recursive-style

Ah, Ok. I just couldn't think of one myself.

Recursion is just a special case loop with redundant state data that expands in size at a rate of O(n)=n where n is the depth of the recursion. That's all it is. There is no recursive function which cannot be written as a loop.

Which also means that for most cases of recursion, you can implement a superior performance version of it by turning it into a loop and cutting down the state space. And with the benefit of removing the unknown state size for most cases of an unknown recursion depth, which can cause stack overflows and such.

For some platforms, like the GPU, you don't even have recursion available for precisely the reason of stack space. The CPU has the benefit of big gobs of memory and cache for each thread to waste; but on the GPU, you've got a few bytes per thread, and so there really is no stack. Even if you could have one, with the hardware restraints, using a recursive algorithm would bring you down to like a 10% or less of your ideal performance just from memory transactions alone.

This is also why most papers about GPU implementations of algorithms are mostly about reducing state space. In the CPU recursive implementations, they waste all this space and jam it in the stack when each call and return stores and loads all the data in and out. On the GPU, the state space needs to be close to nothing for optimal performance.

So in one of the bathrooms inside a building, I found a teddy sitting on the toilet, with glasses on its face, and holding a newspaper open in front of it like it was reading. Twas great.

Then I tried to screenshot it and photobombed myself. Protip: don't use alt+printscreen to try taking screenshots in a game which binds 'holding alt' to 'throw grenade' action. Literal photobomb.

Fun fact: So far this year, a French person has almost as high a chance of dying due to ISIS as an American has of dying due to a police officer.

Quote from: origamiscienceguy on November 14, 2015, 09:21:19 pm

"climate change causes terrorist attacks"

- Senator Sanders 2015

(I don't remember exactly what he said, but that's the gist of what he said.)

I could get behind that. I mean, people already commit terrorism, and if their homes are flooded/otherwise destroyed because of the negligence of the [perceived] Western industrial complex, then yeah, they're gonna go a-bombing.

Not just flooding or destructions; nor is it causing it primarily through ill-will. See, the major point here is that climate change induces drought, floods, and generally conditions that lead to a lack of fundamentally necessary goods like food and water. Historically, lacking such things on a widespread basis is just about the single most effective way to topple a government.

The so-called Arab Spring, for example, which included the Syria uprising, was in large part triggered by a big spike in food prices, exacerbated by climate change. The large number of refugees fleeing war and famine is thus very much influenced by climate change, as are the conflicts they flee, and the criminal acts committed against innocents.

Don't believe me? Well, in that case, try believing the Department of Defense report on the matter. http://www.defense.gov/News-Article-View/Article/612710

Consistency. It's easy to develop for a particular console because you know that they all have the same specs. Remove this, and developers have little reason to stay. Sure, you can upgrade your console to meet a certain performance of a game you want to play, but now developers have to develop for two different components. Considering that things like OpenGL matter incredibly as to what graphics card you are using (some graphics cards do not support the latest OpenGL) this means that developers now need to add new things to their OpenGL code specifically for the higher-end graphics cards, while also maintaining backwards compatibility. With the "vertical support" of the console being maintained indefinitely, this means that so must the code (newer GPUs, etc). Release-and-forget stops being a thing, and developers no longer have a reason to bother with consoles.

As someone who is developing with/familiar with console hardware and graphics in particular, it goes WAY beyond just this.

First and foremost: Console hardware is not general purpose PC hardware. It is custom designed, they often have hardware features which PCs or other consoles don't even have. We aren't talking just different GPU specs, we're talking 'oh hey, this device has a hardware unit built to compute this specific format of float point vectors.' For old game compatibility/emulation, some consoles have even had to physically build in redundant hardware from the previous generation because the hardware was just that unusual.

Second: these things are generally welded together, more or less. Putting together special slots so varying hardware from varying vendors works together adds physical size, expense, and usually some performance opportunity costs.

Third: Console hardware is custom built stuff. Microsoft, Sony, and so on, have their own hardware development teams that design and build these chips from the ground up. And not just build them. Because they are custom hardware, they need custom drivers. They usually have a custom OS too. Oh, and the aforementioned specialized hardware I mentioned? Yeah, you need APIs for that too. So you have special APIs akin to OpenGL which need to be written and designed from the ground up to maximize performance for applications on your platform. And usually, they have low-level graphics APIs similar to the proposed Vulkan spec.

In short, it's damn near impossible to get out a console with one set of hardware, let alone a bunch of redundant interchangeable crap to support.

Like, look at this silliness: https://en.wikipedia.org/wiki/PlayStation_2_hardware
Not one, but 3 different pieces of hardware for processing floating point numbers; two of those being heterogeneous vector floating point units. Then a GPU on top of that. Also 2 Synergistic Processing Units, one of those from the PS1. Shit be complex.

So apparently Carson is really whackadoodle. http://www.theguardian.com/us-news/2015/nov/05/ben-carson-egyptian-pyramids-were-grain-stores-not-pharoahs-tombs

Egypt’s pyramids were built by the biblical Joseph to store grain and were not, as archaeologists believe, tombs for pharaohs, Republican presidential hopeful Ben Carson has said.

Shouldn't the rising sea-levels cancel out the oceanic acidification by dilution?

No. Not even close. They've already decreased their Ph by .1 from what I can tell, and are expected to drop by another .2 in the near future. And considering the difference between pure water and 'all aquatic life is dead' is 2.5 points, .3 is a hell of a lot.

Between the heat and the acidity, most coral reefs are expected to die out in the next 30-40 years. 20% already have. (as of 2010 at least; it's likely closer to 25%-30% today, based on their estimates at the time)