grcumb - Slashdot User

Submission + - New formula massively reduces prime number memory requirements.

Submitted by grcumb on Sunday September 25, 2016 @07:10PM

grcumb writes: Peruvian mathematician Harald Helfgott made his mark on the history of mathematics by solving Goldbach's Weak Conjecture, which every odd number greater than 5 can be expressed as the sum of three prime numbers. Now, according to Scientific American, he's found a better solution to the Sieve of Erasthones:

In order to determine with this sieve all primes between 1 and 100, for example, one has to write down the list of numbers in numerical order and start crossing them out in a certain order: first, the multiples of 2 (except the 2); then, the multiples of 3, except the 3; and so on, starting by the next number that had not been crossed out. The numbers that survive this procedure will be the primes. The method can be formulated as an algorithm.
But now, Helfgott has found a method to drastically reduce the amount of RAM required to run the algorithm:
Helfgott was able to modify the sieve of Eratosthenes to work with less physical memory space. In mathematical terms: instead of needing a space N, now it is enough to have the cube root of N.

So what will be the impact of this? Will we see cheaper, lower-power encryption devices? Or maybe quicker cracking times in brute force attacks?

Submission + - Reuters bans RAW photo format. (petapixel.com)

Submitted by grcumb on Thursday November 19, 2015 @06:38PM

grcumb writes: Reuters is the latest agency to join the ranks of the technically clueless who think that ethical problems can be solved using technical means. They recently issued a circular to their contributors, stating in part: "In future, please don’t send photos to Reuters that were processed from RAW or CR2 files. If you want to shoot raw images that’s fine, just take JPEGs at the same time. Only send us the photos that were originally JPEGs, with minimal processing...." The problem they claim to be addressing is doctored images, but they don't explain how they plan to ensure that the JPEGs weren't simply exported from RAW files with their EXIF data altered, or heck, just altered as JPEG. They also assert that getting JPEG files straight from the camera is quicker, which is fair enough. Lots of professionals shoot with RAW+JPEG at newsworthy events. They can send the JPEGs off quickly to meet the first deadline, then process the RAW files at leisure for higher quality publications.

Submission + - Android Ice Cream Sandwich Source Released (google.com)

Submitted by grcumb on Monday November 14, 2011 @07:13PM

grcumb writes: Looks like the folks at Google have made good on their promise to release the Android 4.0 source code. Android software engineer Jean-Baptiste Queru writes: "Hi! We just released a bit of code we thought this group might be interested in. Over at our Android Open-Source Project git servers, the source code for Android version 4.0 (Ice Cream Sandwich) is now available."

"This is actually the source code for version 4.0.1 of Android, which is the specific version that will ship on the Galaxy Nexus, the first Android 4.0 device. In the source tree, you will find a device build target named "full_maguro" that you can use to build a system image for Galaxy Nexus. Build configurations for other devices will come later."

If the Cyanogen elves get busy Daddy just might be getting a new ROM for Christmas....

Submission + - Economist Mag Profiles "Wireless Carrier-Pigeons"

Submitted by grcumb on Wednesday September 22, 2010 @05:20PM

grcumb writes: The Economist magazine is running a brief profile of Digicel, a 'minnow' in the wireless telecoms market that has distinguished itself by setting up shop in some of the most unlikely (and dangerous) markets in the world, including Haiti and Papua New Guinea, whose capital, Port Moresby, has one of the highest murder rates in the world.

"If you just focus on risk, you can't do a thing," said Digicel's billionaire president Denis O'Brien in a 2008 Forbes profile. But O'Brien's small-market revolution should teach us another lesson, too: Traditional economic analysis doesn't work when it comes to communications. Telecommunications is a supply-driven economy. If you build it — no matter where you build it — they will come.

Now, if someone could just teach the North American telcos this....

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