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Comment Re:Europe (Score 5, Informative) 160

That's the key question: Unless you have an available open access frequency band, this standard is just wishful thinking instead of a new product.

The current allocations in Europe ( covers all of 890-942, 942-960 and 960-1164 MHz, with usage mostly cell phone, radio-navigation and broadcasting.


Comment Why didn't they optimize the new generator? (Score 1) 136

The new 128-bit generator is shown as this piece of code, using a pair of 64-bit state variables:

uint64_t state0 = 1;
uint64_t state1 = 2;
uint64_t xorshift128plus() {
    uint64_t s1 = state0;
    uint64_t s0 = state1;
    state0 = s0;
    s1 ^= s1 > 17;
    s1 ^= s0;
    s1 ^= s0 >> 26;
    state1 = s1;

The absolute minimum latency of that code is 8 clock cycles, assuming that the two initial loads happen at the same time and that the writeback of s1 to state1 is overlapped with the return, i.e. free.

It seems like an obvious optimization to notice that s0 could be updated in parallel with the two initial s1 updates, i.e.

    s1 ^= s0;
    s1 ^= s0 >> 26;

can instead be written as

    s0 ^= s0 >> 26; // These two clock cycles can be overlapped with the previous s1 updates!
    s1 ^= s0;

since we don't care about the s0 value after this point and XOR operations are commutative (it is of course possible that the compiler is smart enough to do the same optimization, but I doubt it):

This is two clock cycles faster than the original code.


Comment Rubylith was state of the art! (Score 3, Interesting) 60

My father spent months at his home-made light table back around 1965 cutting traces in rubylith film in order to create the offset masks for orienteering maps.

He needed one such mask for each color in the finished map, any mistakes had to be fixed with small amounts of red lacquer which then had to dry completely before it could be recut.

The big advantage for VLSI vs a map was that most lines were straight so you didn't need to trace curved lines like you do for the contours on a map.


Comment Re:And where does "velocity" come from? (Score 1) 131

Sorry, that's simply wrong:

The basic output (usually once per second for most GPS chipsets) consists of 7 parameters:

X,Y,Z and dX,dY,dZ along with T, wth the x,y,z values in an Earth Centered Earth Fixed coordinate system. I.e. velocity is an intrinsic output of the processing, resulting from the need to determine doppler values for all visible sats in order to track them.

Past this point many GPS units will do lots of post-processing, for some of them this includes using a lowpass filtered velocity model that uses position deltas instead of or in addition to the raw velocity outputs.

I have run over 500 orienteering races with various GPS units (mostly Garmin watches), and it is indeed true that tracking under a canopy (particularly when it is wet) can be a big challenge, but since the SirfSTAR chipset took over from Garmin's old 12-channel receiver, it is now perfectly usable.

Regarding the original article: Distance measurements depend a lot on how the GPS filters individual measurements!

If you are running along a standard road, then your actual path will be pretty much identical to a set of straight lines, simply because the usual curves on a road are so wide that you get many GPS updates along them. The same goes for XC skiing where a GPS can easily overestimate the distance by introducing spurious sideways noise.

My wife's iPhone consistently overestimate the length of the XC ski tracks in Rauland, Telemark (Norway) due to this: Since I have mapped this entire area I can measure the exact lengths directly from the aerial photos and they corresponds much better with my Garmin 620 and 410 watches. My Garmin Montana which has a much better antenna will normally provide significantly better tracking.


Comment Log tables for the win! (Score 1) 220

I had both the school issued smallish slide rule and one I had inherited from my father which was much nicer.

However, I used log tables when I wanted even more accurate answers: One year my main wish on my Christmas list was a book that provided full 5-digit log tables. :-)

After I read about Taylor series I realized that I could calculate anything to any accuracy I wanted, but it still took a couple of hours (high school physics class) to calculate pi by hand with 20+ digits using the arctan formula.

(At this point in time, ~1975, I had just bought my first calculator, a TI SR50A which still works when I connect it to a couple of AA batteries instead of the original NiCd rechargable.)


Comment This is a SF story, sort of (Score 2) 130

Last night I bought a Baen EBook: Terry Bisson - Numbers Don't Lie.

The book consists of three stories, one of them is about a "Hole in the Hole", a Brooklyn junkyard which uses a spacetime rift connecting the junkyard to the Moon in order to get rid of old tires. Our protagonists tries to use said rift to retrieve one of the three Apollo Moon buggies that were left behind.


Comment The US wants Instant Gratification (Score 4, Interesting) 439

Having lived in the US previously, I much prefer the Norwegian (and most of the EU) model where you go online or to a dealer and figure out exactly which car you want:

Engine, paint, transmission, seats etc, then you haggle a bit about the price and order it, with delivery a number of weeks later.

In the US it seemed dealers really needed to be able to deliver a car TODAY, not tomorrow or next week.

Personally I ordered a Tesla 4WD model a few days ago, for delivery in the beginning of March.

The main difference from my last car was in the fixed sticker price: No haggling about rebates, just a simple take it or leave it offer.

The main reason for getting a Tesla here in Norway is of course our incredibly high import duties and taxes on regular cars (a car with a V8 engine would probably cost 2.5 to 3 times as much as in the US), while a Tesla has no import duties, no sales tax, no road fees and lots of free parking & charging. In a couple of years they have stated that the relative subsidies for zero emission vehicles will get a cap, so only smaller cars will be able to take full advantage.


Comment Re:work to live (Score 1) 55

I live in Norway where we definitely work to live, not the opposite, but I did spend one year in the US back in 1991-92.

During that year I know that I worked the least number of hours of any of the engineers in my department, averaging 45 hours/week, but I still got a couple of bonuses which they really didn't need to give me, since they knew that I was going back to Oslo after 12 months.

Here in Norway we have 5 weeks of vacation time every year, and employers get in big trouble if they have any employees who don't take all of that. (You can push a maximum of two weeks in front of you from one year to the next.)

OTOH my wife would gladly confirm that I spend a lot of hours in front of my PC every day, but I consider that to be some of my hobbies, not work. :-)

I.e. stuff like NTP Hackers, Mill Computing, Lidar-based mapping work etc.


Comment What about the interconnect? (Score 1) 150

In pretty much every HPC cluster I've seen or been personally involved with (mostly oil/seismic processing or crash simulations), the type of CPU is only one of the cost drivers!

Typically you end up spending about as much on fast interconnects as you do on motherboards/cpus/ram etc. The main exception to this rule is when you have an embarrassingly parallelizable workload, with small memory footprint and no need for cross-system communication, i.e. like a Monte Carlo simulation or password cracking.

For oil we used the largest single-image NUMA/SMP machine we could get at the time, this machine did the initial gridding of the problem space, then a standard cluster of 1K dual-cpu motherboards (i.e. 2K cpus) took over and did the main part of the actual processing.

There are exceptions though, like if you are doing Linear Programming type optimization which can be really hard to parallelize, or if you are using very expensive SW:

When you pay more for the SW than for the HW it is running on, then it makes sense to use bleeding-edge (gamer type) cpus.


Comment Rather a very poor job. :-( (Score 1) 100

I have made many, many panoramas, but none in the multi-gigapixel range, so I realize that they had a very tough stitching job, but even so: This was a pretty bad job!

All the central snow fields look like the result of randomly placed images: With a motorized pano head they should have been able to locate each image pretty accurately even before they started the SIFT runs to look for matching key points (which can be hard in a blue sky or on white snow).

More problematic is the fact that they must have done the actual stitching pretty much without proper blending from one image to the next:

Within the first minute of zooming around in the image I stumbled across a perfectly straight line with totally different exposure/lighting on each side, giving an almost black/white boundary that screams "This isn't natural!".

The proper way to blend such images is to use a multi-spectral approach: Low frequency information (like average light level) is blended across the entire overlap, while higher frequencies use narrower and narrower bands. Doing it this way means that even if one image had a clear blue sky and the next was taken when the sun was hidden by a cloud, the overlap is nearly perfect.


Comment Nash just got the Abel price! (Score 5, Informative) 176

Just 5 days ago, John F. Nash and Louis Nirenberg got the Abel price in a ceremony in Oslo:

With a diploma handed over by the Norwegian King Harald and a NOK 6M prize this is the closest thing math has to a Nobel prize.

Unlike the Fields Medal there is no age limit, so just like the Nobel prizes it tends to be given out at a later date, for work that has proven itself to be really outstanding.


Comment I mosly agree with you... (Score 1) 40

The first big problem with integers is that they are really badly defined in C, so just like you I try to use unsigned as much as possible:

Any underflow turns into a big overflow, so it can be tested for at the same time as the overflow test, and the semantics of power-of-two sized wraparound is pretty solid on all platforms and implementations.

OTOH I don't agree that having proper overflow handling would mostly be a new source of bugs, i.e. on the new Mill cpu architecture we have a full orthogonal set of of all basic operations:

When adding two numbers (belt values) you can specify signed or unsigned, and over/underflow to be handled as saturating, wraparound or trapping, as well as automatically widening.

Look at ADDSW as an example of a Signed ADD that will widen if needed.

Since the Mill carries metadata alongside each belt slot it does not need separate byte/short/word/dword ADD instructions: The size of the operations is defined by the belt slot specified and not in the instruction encoding, so the machine code is polymorphic in data item size.

I.e. you can start with 8-bit values and an 8-bit accumulator, when the sum becomes too large then it is automatically widened to 16 bits or more. This works all the way to 128 bits for all scalar operations.


Comment Bad applications and programming languages! (Score 1) 486

What they actually compared wasn't the speed of the disks, but the speed of the language runtime and OS file IO buffering routines!

It wasn't really that surprising that concatenating java or phyton objects can be slower than letting the low-level runtime do the same task.

If they had wanted to test the disk IO speed then they would have had to add at least some fflush() calls.

It is trivial, in any language, to make your code faster than the actual disk transfer speed, but a lot harder to make it faster than a set of small block moves within (cached) RAM.


Comment Language obviously influences thinking! (Score 1) 274

I'm Norwegian which meant that I had to learn the two main Norwegian languages (bokmål and nynorsk, used to be about 30% overlap, it is larger now) and English. Those are ones I'm currently fluent in. I also had four years of German and two years of French, plus a single year of Old Norse (i.e. Icelandic).

The interesting part here is that the list above was the absolute minimum I could get away with, since I knew very early that wanted to get a technical degree (MSEE from NTNU in Trondheim).

Fluency in any language requires thinking in that language, this is so obvious that only mono-lingual people could possibly doubt it!

Thinking about stuff you have no way to express in language is extremely hard. :-)


Comment Re:Not GoDaddy. (Score 5, Interesting) 295

I've had a single .org domain registered with and hosted by DreamHost for 7-8 years now, absolutely no problems.

I also have 6-8 other domains here in Norway (.no) which are all registered locally but still hosted on the same DreamHost account.

Dirt cheap, very stable and OK performance wise.

I have a tiny search program written in perl ( which allows you to search for any given string within the first billion digits of pi:

Even though the database + index needs about 5 GB, so obviously not cached in memory, I tend to get replies within 0.1 seconds or so:

Find 19570725

Found at 45,109,789: 061632112341128 19570725 293694235201198

Total time = 0.099406 seconds (8 suffix lookups)

I.e. my birth date is located about 45 million digits into pi. :-)


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