* Posts by Nick 26

15 posts • joined 16 Jun 2009

Uncle Sam bungs rich tech giants quarter of a billion bucks for exascale super R&D

Nick 26

>They need to yank IBM out of this group, as they have no products nor services that qualify them to produce anything, on this scale

OpenPOWER

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Meet the chap open-sourcing US govt code – Paul, an ex-Microsoft anti-piracy engineer

Nick 26

Re: Significant legal risks of open-source software

>It took them18 months to publish their own code under the LGPL?

That depends on whether it was completely in-house project, whether they started with an already existing application and adapted it or whether multiple entities worked on the software from different projects in a collaborative fashion.

My guess it that the copyright wasn't transferred by the authors when it was being written so they had to do a code audit, find all the authors wherever they are now and ask them to sign a form before they could change the license.

Another factor was probably the issue (as mentioned in another comment) that anything produced by the US government is automatically public domain. If the government funded part of the development then that might have needed some legal checks to make sure they could actually release under GPL.

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AMD is a rounding error on Intel's spreadsheet and that sucks for us all

Nick 26

Re: Sigh

>Opteron is still in the number three super computer...

Yes, but that machine is 4 years old.

More relevant to the current health of competition is the chip manufacturer for the new machines in the last release of the Top 500 list. There were 154 new machines, 153 of them used various models of Intel CPU and 1 of them used a Sunway CPU (the new Chinese-designed #1 machine).

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Linux command line mistake 'nukes web boss'S biz'

Nick 26

I done plenty of deleting directories I didn't mean to using badly defined variables but two similar cockups stand out in my memory:

The first I've done a few times is accidentally adding an additional / to the "src" of an rsync command when trying to update a subdirectory, for example:

$ ls /bar

aaa bbb ccc ddd eee

$ ls /path/to/foo

file

$ rsync -a --delete /path/to/foo /bar

$ ls /bar

aaa bbb ccc ddd eee foo

$ rsync -a --delete /path/to/foo/ /bar

$ ls /bar

file

There's then a slow dawning realisation of what's happen, I swear profusely and think "oh shit, where can I get that data back from?"

The other was when I was a young misguided tcsh user and I was telling some veteran ksh users how good it was because it had features like "set rmstar" where it would warn you if you do "rm *" and proceeded to demonstrate this in my home directory on my network login on a different machine than I normally use in a shell where it was unset, much hilarity ensued.

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Nick 26

> Backups?

The story went that the backups were in a mounted directory which rm happily traversed and trashed, which is not an inconceivable scenario if a naive user was backing up to a network share or Dropbox.

In the age of ransomware it's become even more important not to store backups anywhere they can be easily accessed.

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Nick 26

Re: Whilst you're here...

> rm -rf .*

Most modern implementations of rm trap this. For example in the latest OS/X:

$ rm -rf .

rm: "." and ".." may not be removed

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Google says its quantum computer is 100 million times faster than PC

Nick 26

Carefully chosen benchmark comparison

Classical simulated annealing is not a particularly good optimization technique which was acknowledged in the paper:

"It is often quipped that Simulated Annealing is only for the 'ignorant or desperate'."

There are much better classical optimization technique which would compare much more favourably but they used it because it was the closest analogue to quantum annealing.

Simulated annealing also doesn't do well with potential energy surface which contain deep, narrow wells where it can get trapped. Quantum annealing can tunnel very efficiently through them and so they chose a problem which suited it. From the paper:

"carefully crafted proof-of-principle problems with rugged energy landscapes that are dominated by large and tall barriers"

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'iOS 9 ate my mobile broadband plan'

Nick 26

Easy fix is to turn off mobile data for hungry apps

I was hitting my data limit before WiFi-assist.

I went with the strategy of turning off mobile data for every app I had installed.

I then turned it back on as and when I first needed it.

I haven't hit my data cap since, not even with WiFi-assist and haven't noticed any loss of functionality.

iOS gives you the information about how much data different apps are using right in the settings,

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Troll sues Apple for daring to plug headphones into iPhone

Nick 26

Not necessarily two sockets

Nathan Hobbes wrote: "Not to state the obvious, but this explicitly talks about having 2 separate sockets, one for handsfree (mic/headphones) and one just for headphones"

Claim 1 ends with "said input-output and output interfaces to be jointly employed for said first and second headsets where said first and second headsets being the same headset" which at a stretch capturess the single connector with a single headset option.

In that case the prior art would be a mobile phone which played music/radio before 2001.

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Study: Climate was hotter in Roman, medieval times than now

Nick 26
Pint

Vineyards in York (-ish)

Just to add another post about the irrelevancy of the Romans having vineyards in York, a vineyard is currently operating just down the road in Leeds:

http://www.englishwineproducers.com/leventhorpe.htm

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IBM US nuke-lab beast 'Sequoia' is top of the flops (petaflops, that is)

Nick 26

@ John Savard

"one thing that wasn't mentioned was latency - or single-thread performance. Not everything can be parallelized well."

If your problem doesn't parallelize well and single thread performance is your main concern then you would buy a different (and much cheaper) machine.

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Slovakian police chief quits over Dublin explosives run

Nick 26

Yes it was safe

The pilot was right.

RDX is very stable.

They could have used it to boil the water for the in-flight drinks because it burns rather than explodes (although it's not something I'd advocate trying).

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Top 500 supers - world yawns at petaflops

Nick 26

Re: F@H

Chris Simpson wrote:

"What about Folding@Home, Granted not one single computer but 5+ Petaflop"

What Folding@Home does is millions of slighty different small problems.

What a supercomputer does is one very large problem.

The difference is tolerance to latency.

The answer to one F@H problem is independent of the other problems and so it can be task farmed. If you're dealing with one big simulation then you need as fast as possible communication between all the CPUs otherwise you'll be waiting an eternity for your answer.

Let's say you want to do some molecular dynamics on a piece of material the size of a grain of salt. Just holding the coordinates and velocities of all the atoms would require about 10 petabytes of memory. The drive for larger simulations, smaller approximations and finer resolutions will continue to feed these machines although Amdahl's law and other software engineering problems are raising their heads.

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That Digital Britain report in full

Nick 26

FM

The reason they want to close down FM is so that they can flog the frequencies to mobile networks

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