Hackaday Links: October 6, 2012

October 6, 2012 by Brian Benchoff 33 Comments

Upgrading a desktop with a diamond cutting wheel

[Michail] needed a new graphics card. The only problem was his motherboard didn’t have any free PCI-E x16 slots available. Unable to find a PCI-E x1 card, he did what any of us would do and broke out the Dremel. Yes, he got it working, but don’t do this unless you know what you’re doing.

It’s recycling!

[Steve] recently got a Galaxy S3 and was looking for something to do with his old phone. It’s got WiFi, it’s got a camera, and with a free app, [Steve] now has an IP Webcam. Neat way to recycle a phone.

This is now bookmarked

We’re not much for plugging other blogs, but Math ∩ Programming – that’s intersection, remember – is really cool. Apparently it has been around for a little more than a year and already there are quite a few really cool posts. How to use cellular automaton to generate caves in video games and facial recognition through Eigenvalues are amazingly in depth, and show the theory behind some really cool techniques. Very, very cool.

Troll Physics: now wireless!

Remember [Fredzislaw100], the guy who puzzled the Internet with impossible circuits? He’s back again, this time with wireless LEDs. We’re guessing something similar to an induction charging system in the battery clip, wirelessly coupled to something under the paper, and that is wirelessly coupled to the LEDs. Your guess will probably be better than ours, though.

Not shown: Captain Obvious, Major Major

Pv2 [Zachary Ricks] of the U.S. Army thought we would get a kick out of the last name of one of the guys in his company. Yes, it’s ‘Hackaday,’ and yes, it’s a real surname. Here’s the full pic [Zach] sent in. Apparently it’s a name along the lines of ‘Holiday.’ Honestly, we had no idea this was a real surname, but we’re thinking Private Hackaday could use a care package or two (dozen).

Anyone up for sending a few hacker friendly (for [Zach] and a few other guys) care packages? Even socks or books or Oreos would make for an awesome care package. Email me if you want the mailing address.

Calculating Pi To 10 Trillion Digits; The Last Number Is 5

November 28, 2011 by Brian Benchoff 44 Comments

In August, 2010, [Alexander Yee] and [Shigeru Kondo] won a respectable amount of praise for calculating pi to more digits than anyone else. They’re back again, this time doubling the number of digits to 10 Trillion.

The previous calculation of 5 Trillion digits of Pi took 90 days to calculate on a beast of a workstation. The calculations were performed on 2x Xeon processors running at 3.33 GHz, 96 Gigabytes of RAM, and 32 Terabytes worth of hard drives. The 10 Trillion digit attempt used the same hardware, but needed 48 Terabytes of disk to store everything.

Unfortunately, the time needed to calculate 10 Trillion digits didn’t scale linearly. [Alex] and [Shigeru] waited three hundred and seventy-one days for the computer to finish the calculations. The guys used y-cruncher, a multithreaded pi benchmarking tool written by [Alex]. y-cruncher calculates hexadecimal digits of pi; conveniently, it’s fairly easy to find the nth hex digit of pi for verification.

If you’re wondering if it would be faster to calculate pi on a top 500 supercomputer, you’d be right. Those boxes are a little busy predicting climate change, nuclear weapons yields, and curing cancer, though. Doing something nobody else has ever done is still an admirable goal, especially if it means building an awesome computer.

Tilt Compensation When Reading A Digital Compass

October 25, 2011 by Mike Szczys 16 Comments

If you’re familiar with using a compass (the tool that points to magnetic north, not the one that makes circles) the concept of holding the device level makes sense. It must be level for the needle to balance and rotate freely. You just use your eyes to make sure you’re holding the thing right. Now think of a digital compass. They work by measuring the pull of a magnetic field, and have no visual method of showing whether they’re level or not. To ensure accurate readings you might use an accelerometer to compensate for a tilted magnetometer.

The process involves taking measurements from both an accelerometer and a magnetometer, then performing calculations with that data to get a true reading. Luckily the equations have been figured out for us and we don’t need to get too deep into trigonometry. You will, however, need to use sine, cosine, and arctangent in your calculations. These should be available in your programming language of choice. Arduino (used here) makes use of the avr-libc math library to perform the calculations.

Snow Leopard Ditches Real Math For Fake

September 1, 2009 by Mike Szczys 173 Comments

snow_leopard_fake_math

We’ve always felt that hard drive manufacturers were dirty crooks because of their use of fake math to make drives sound bigger than they actually are. Here’s a quick refresher for those who need it: Because digital information consists of 1’s and 0’s (two possible settings), digital architecture revolves around powers of 2. Long ago, when nomenclature was setup for measuring data the term kilobyte was adopted to represent 2 to the 10th power bytes (base 2, aka real math). The problem here is that 2^10= 1024 and when laymen hear the root “kilo” they think 1000 which is 24 byes less (base 10, aka fake math). So, if you have a 500,000,000 byte drive, base 10 math would call that a 500GB drive, but base 2 math would call that 476.8GB.

We understand why hard drive manufacturers use the base 10 system; larger sounding drives sell better. Now we find out that OSX 10.6 Snow Leopard is using base 10 math to calculate storage space. While base 2 math is the standard storage measurement for operating systems it may at first be difficult to understand why Apple would change to a base 10 system. But think about it once more, doesn’t Apple have a lot to gain if all the storage-containing-hardware they sell sounds bigger than it actually is?

[via Gizmodo]

Update: Force Snow Leopard to calculate storage in base 2 [via Gizmodo]