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A modern 64-bit CPU should be able to do double precision in the exact same time it takes to do single. The only difference is how many bytes (8- 4) are needed to store the answer. Personally, I'd use double precision to the bitter end and then format to any desired width. BTW, my Garmin GPS uses single, but military GPS systems use double for coffee mug precision (a thimble if the antenna would fit) and quad to position (station) satellites.
If you find yourself in a fair fight, your tactics suck. - John Steinbeck
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True, in most cases such accuracy is unnecessary and thus just CPU cycles wasted. But there are situations where the accuracy could make for easier accomplishments later.
Around 2000 the AutoCAD product changed the way it stored polylines (non regular polygons) - the old way was to save each line/arc segment in series as doubles for XYZ values. This had the detriment that the further you move away from 0,0,0 the worse accuracy became, to the point where such polygon was displayed as dis-joint vectors. The "new" method used a start point, then a length, angle and "bulge" for each vector - made computation a lot faster and the polygon itself didn't loose accuracy because of distance from origin. BUT it has a secondary inaccuracy in that its interaction with other objects became prone to errors - which in turn made things like hatching (fill the space between vectors) very problematic.
Anyhow, there are quite a few ways people have tried to get both accuracy as well as speed from these figures. As an example: http://keithbriggs.info/mpfs.html[^]
So it seems it's something which just always needs to be chosen on a per-problem basis. Similar to the speed-vs-memory trade-off of using BST / HashTable.
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That's not good - it's going to by very difficult to get an investigation team in there to find out what happened.
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952)
Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
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Not sure how wise it was to fly over a conflict zone.
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I was asking the same question.
I remember that at the beginning of the Kosovo war, I was flying from Montreal to Mumbai via Amsterdam; while waiting for the plane in Amsterdam, there was an announcement telling us that NATO started bombing Serbia, they had to recompute all air routes that passed in that area and get different national authorizations because they had to fly over different countries.
I'd rather be phishing!
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not sure 'lost' is the right word for it. and i'm not sure Malaysian Airlines had much to do with it.
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It was at the time.
Quite interesting listening to the radio as the story developed from knowing nothing and where their information came from.
First mention of it being shot down was on Ukrain government fella's Facebook, then the rebels said it wasn't them on their twitter account. First film was uploaded on YouTube.
BBC have teams sifting through the internet, looking for related information, trying to verify it, translating it.
Some men are born mediocre, some men achieve mediocrity, and some men have mediocrity thrust upon them.
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I'm not sure I would have gotten on that one! 
Once you lose your pride the rest is easy.
I would agree with you but then we both would be wrong.
The report of my death was an exaggeration - Mark Twain
Simply Elegant Designs JimmyRopes Designs
I'm on-line therefore I am.
JimmyRopes
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I recognize some of those pictures from larger ones I saw before. They carefully cropped out the parts with the mangled dead bodies.
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They didn't "lose" the plane - it was shot out of the sky. The fun part is going to be watching the two most likely suspects pointing fingers at each other, heavily infused with righteous outrage from people of all nationalities who don't really give a shit.
The plane was at 33k feet - and was evidently squawking it's IFF signal, because it was being tracked by your everyday internet flight trackers when it dropped off.
That means that it wasn't accidental.
Does Russia have technology to shoot down at plane at that altitude? Yes.
Does Ukrain have the capability? Yes.
Does the CIA have the technology? Yes.
Who actually did it? We'll probably never know.
".45 ACP - because shooting twice is just silly" - JSOP, 2010
-----
You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
-----
When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013
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I'm not sure I would be flying over Ukraine at the moment (or, probably about 50% of the world for that matter.)
Marc
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Marc Clifton wrote: or, probably about 50% of the world for that matter
I would have mentioned that if you had not.
There are very few flight path that do not take you over a conflict.
Fortunately there are only a few conflict zones that have the capability of shooting down a airplane flying at a little over 10Km.
Obviously, the Ukraine is one of them and should be avoided by commercial flights.
Once you lose your pride the rest is easy.
I would agree with you but then we both would be wrong.
The report of my death was an exaggeration - Mark Twain
Simply Elegant Designs JimmyRopes Designs
I'm on-line therefore I am.
JimmyRopes
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The actual route is decided by the pilot taking into account guidance from their airline so as a passenger you don't get any say on that unless the airline publishes that guidance in which case you can decide whether to use them or not.
In this case airspace was closed to commercial flights below 32000 foot and this was flying at 33000 which was believed to safe from the use of portable anti airraft weapons. Long range SAMs were not considered likely probably naively.
I suspect following this airlines will avoid the area totally.
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The anti-Kiev fighters had just bragged about capturing some Buk systems. And as far as I know they have no airforce so the govt forces don't need to use SAMs. They also bragged about downing a plane other than the Su-25 and hastily deleted the brag once news of civilian aircraft vanishing appeared 
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The Buk system seems to a Soviet / Russian equivalent to the US Patriot...
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glennPattonPUB wrote: The Buk system seems to a Soviet / Russian equivalent to the US Patriot...
A moot point to the passengers of the ill fated flight. 
Once you lose your pride the rest is easy.
I would agree with you but then we both would be wrong.
The report of my death was an exaggeration - Mark Twain
Simply Elegant Designs JimmyRopes Designs
I'm on-line therefore I am.
JimmyRopes
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I was thinking, that you have to know what you are doing to use one. It's not telescopic sight, push the button thing there is a bit more to it...if the users knew enough to get a good launch, track & hit with it, they had to know what they were firing at was a Su-25...
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glennPattonPUB wrote: if the users knew enough to get a good launch, track & hit with it, they had to know what they were firing at was a Su-25
They knew what they were firing and what their target was.
Once you lose your pride the rest is easy.
I would agree with you but then we both would be wrong.
The report of my death was an exaggeration - Mark Twain
Simply Elegant Designs JimmyRopes Designs
I'm on-line therefore I am.
JimmyRopes
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greldak wrote: In this case airspace was closed to commercial flights below 32000 foot and this was flying at 33000 which was believed to safe from the use of portable anti airraft weapons. Long range SAMs were not considered likely probably naively.
I suspect following this airlines will avoid the area totally.
One can hope.
Once you lose your pride the rest is easy.
I would agree with you but then we both would be wrong.
The report of my death was an exaggeration - Mark Twain
Simply Elegant Designs JimmyRopes Designs
I'm on-line therefore I am.
JimmyRopes
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3D Homunculus Nebula [^]
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." Red Adair.
Those who seek perfection will only find imperfection
nils illegitimus carborundum
me, me, me
me, in pictures
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Wow, I think looks kinda like a shelled peanut, maybe a day with less caffeine is needed to make sense!
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Four web browsers(opera, safari, firefox, chrome) reports the answer to the following calculation *incorrectly*:
((54/31)+140)
Those 4 browsers return the value : 141.74193548387098
IE reports the value of : 141.74193548387097
Note:The two leading #s in the next example are just for alignment.
if you calculate 54/31 using javascript and browser you get:
##1.7419354838709677
The second one calcs the same equation and simply adds 140 ((54/31)+140) -- to change precision.
141.74193548387098
Notice the digit after the last 9 in the sequence. The rounded up value should be a 7 (round up from 6), but it is reported as an 8 in every browser except IE. You can also compare the value to Windows Calculator for 54/31.
Windows calculator gives : 1.7419354838709677419354838709677
Interesting?
Here's the HTML / JavaScript so you can copy / paste and try in all browsers:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
</head>
<body>
<div>Clicking the [Calc] button runs two calculations and shows the result on this page. First calc is: (54/31)</div>
<span style="color:red">Note:</span><span>The two leading #s are just for alignment.</span>
<p id="p1">
</p>
<p id="p2">
</p>
<div>The second one calcs the same equation and simply adds 140 ((54/31)+140) -- to change precision.</div>
<div id="extra" style="color:blue"></div>
<input type="button" value="Calc" onclick="DoCalc()"/>
<script type="text/javascript">
var p1 = document.getElementById("p1");
var p2 = document.getElementById("p2");
var extra = document.getElementById("extra");
function DoStart()
{
testdiv.textContent = "started";
}
function DoCalc()
{
p1.textContent = "";
p1.textContent += "##" + 54/31;//calcObject1.y / calcObject2.x;
var outval = ((54/31)+140);
p2.textContent = outval.toString();
extra.textContent = "Notice the digit after the last 9 in the sequence.";
extra.textContent += " The rounded up value should be a 7 (round up from 6), but it is reported as an 8 in every browser except IE.";
extra.textContent += " You can also compare the value to Windows Calculator for 54/31. Interesting?";
}
</script>
</body>
</html>
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That's in the 17th SF so I think it's just hitting double precision. I get the same (apparently) wrong answer using double precision arithmetic in .Net too. If I use arbitrarily extended precision I get
141.74193548387096774193548387096774193548387096774193548387096774...
... which seems right as it's a repeating fraction.
I guess IE's JS engine uses some extended precision (128 bit?) floating point API behind the scenes.
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That didn't really prove anything yet. I'll do the math though, will report back.
Ok then, the results are in. And guess what: it's IE that's wrong.
(54.0 / 31.0) + 140.0 evaluated with IEEE 754 doubles in Round to Nearest mode (as JavaScript demands, right?) gives exactly:
141.741935483870975076570175588130950927734375 (exact representation of the correct result)
141.74193548387097 (ie)
141.74193548387098 (correct conversion to 17 digits)
That 54/31 seems to give 1.7419354838709677 is really irrelevant, because
0) that's not what it gives. It gives 1.7419354838709677490982130620977841317653656005859375 (exactly).
1) a Number in JS is not a 17-digit decimal string that is manipulated like we learn in elementary school, it's a an IEEE 754 double.
modified 17-Jul-14 12:28pm.
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