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Comment Re:Is FORTRAN still winning? Was Re:Poor Alan Kay (Score 1) 200

Repeatedly allocating and deallocating can give a huge performance hit, so I tend to do all my allocations before the main loop.

which is the correct way of doing it. Allocating and deallocating, especially larger chunks of memory, requires you to interact with the operating system.
This should off course be avoided in tight loops.

Comment Re:Is FORTRAN still winning? Was Re:Poor Alan Kay (Score 1) 200

I've been writing a scientific simulation in Fortran for half a year now. I usually like to write in some combination of C and Python.

While Fortran does make the life of a compiler writer easier, I think C benefits from being a small and very popular language.
C compilers are just more advanced, which gives it the speed advantage. But the speed difference for most purposes is negligible.
Choosing the right algorithm and approximations is a much more important concern (factors of 10-100-1000 vs. 1.1-1.2-1.3).
Dynamic memory management is not much different from C.

In my experience, Fortran is extremely useful for expressing linear algebra, which is heavily used in quantum mechanics.
At least it is much much better than C. So in terms of programmer efficiency in scientific calculations, I think Fortran beats C by quite a margin.

Fortran sucks at pretty much anything else though. For example, I think it's a lot easier to have a config module (e.g. class) to manage simulation parameters and recompile the whole application every time you change settings than it is to use an actual configuration file.

The next time I write a scientific application, I think I will have Python handle the logistics (parallelization, files, user input, etc.) and let Fortran do the (heavy) computations.

Networking

The Standards Wars and the Sausage Factory 234

Esther Schindler writes "We all know how important tech standards are. But the making of them is sometimes a particularly ugly process. Years, millions of dollars, and endless arguments are spent arguing about standards. The reason for our fights aren't any different from those that drove Edison and Westinghouse: It's all about who benefits – and profits – from a standard. As just one example, Steven Vaughan-Nichols details the steps it took to approve a networking standard that everyone, everyone knew was needed: 'Take, for example, the long hard road for the now-universal IEEE 802.11n Wi-Fi standard. There was nothing new about the multiple-in, multiple-out (MIMO) and channel-bonding techniques when companies start moving from 802.11g to 802.11n in 2003. Yet it wasn't until 2009 that the standard became official.'"

Comment Re:Space/time duration/distance (Score 3, Interesting) 81

Seven billion light years away (seven billion years ago)

I may not have this right, but due to the expansion of space, wouldn't it have been closer than seven billion light years away at the time of the kaboom? And if the light's taken seven billion light years to get here, space will have expanded further, so the remnants would now be further than seven billion light years away. Right?

Or is this the sort of thing where you can be specific about the distance, or the time, but not both?

Wikipedia has an answer, but I think the above is just meant to give the layman some rough understanding of what's going on.

Beware that it is extremely difficult to measure these kinds of distances exactly. The figure may be a few orders of magnitude wrong, so whether you take into account the expanding universe or not may not be that important...
Cosmologists measure everything in gigaparsec. 7b light years is only 0.3 GPc so it may not be that important.

Science

CERN Physicists Generate Hottest Man-Made Temperatures Ever: ~5.5 Trillion K 107

Diggester sends this quote from Nature News: "Physicists at CERN's Large Hadron Collider have achieved the hottest man-made temperatures ever, by colliding lead ions to momentarily create a quark gluon plasma, a subatomic soup and unique state of matter that is thought to have existed just moments after the Big Bang. The results come from the ALICE heavy-ion experiment — a lesser-known sibling to ATLAS and CMS, which produced the data that led to the announcement in July that the Higgs boson had been discovered. ALICE physicists, presenting on Monday at Quark Matter 2012 in Washington DC, say they have achieved a quark gluon plasma 38% hotter than a record 4 trillion degree plasma achieved in 2010 by a similar experiment at Brookhaven National Laboratory in New York, which had been anointed the Guinness record holder."

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