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#51
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Runway ID
Lakeview Bill wrote:
The runway is NAMED Runway 5. Why would you prepend a zero to a NAME? Because the ICAO standard says that a runway name has always two digits. Why? To minimize the possibility of misunderstandings, especially with pilots and/or controllers who don't speak English as their first language and/or when the radio quality is marginal. As far as I know, all countries adhere to this standard... well, all except one, of course. Stefan |
#52
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Runway ID
On Mon, 17 Oct 2005 03:18:03 GMT, Jose
wrote: This is correct rounding, but it is it what George stated. He stated "round 1/2 to the EVEN number.", which would imply .245 - .26 which is not true. What =is= true is .245 - .25 .255 - .26 .265 - .27 This is not "rounding 1/2 to the even number". Jose, you are with the majority, and you are with what it being taught in today's schools until higher level mathematics. The round (exactly) half to the even is correct. 0.2449 - 0.245 - 0.24 - 0.2 but the 0.24 is not for this rule, rather because the full precision number was under 0.5 0.3499 - 0.350 - 0.35 - 0.3 but again, rule isn't applicable 0.3501 - 0.350 - 0.35 - 0.4 but rule isn't applicable you have to round from the full precision to the final value in 1 step; the sequential above is interesting, but not as it is done for the reasons obvious above. 0.5 (exactly) - 0. 1.5 (exactly) - 2. 2.5 (exactly) - 2. 3.5 (again, exactly) - 4 or, fwiw, 1234.5 - 1234. and 1235.5 - 1236. It used to be taught that way in elementary school, but was changed between when I went to school (1950s) and when my children went to school (1990s). My son has a math degree, and remarked about how higher level high school and college profs complained about having to correct the elementaty and middle teachers teaching, but that they taught what they were given, so it wasn't their fault. |
#53
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Runway ID
0.5 (exactly) - 0.
1.5 (exactly) - 2. 2.5 (exactly) - 2. 3.5 (again, exactly) - 4 No. 0.5 (exactly) - 1. 1.5 (exactly) - 2. 2.5 (exactly) - 3. 3.5 (again, exactly) - 4. Do you have a printed reference for what you espouse above? Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
#54
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Runway ID
"GeorgeB" wrote in message
... Jose, you are with the majority, and you are with what it being taught in today's schools until higher level mathematics. The round (exactly) half to the even is correct. George, you're right that rounding is often performed as you say (i.e., exactly half rounds to the nearest even integer), for the reason you say (to avoid statistical biasing). But I'd quibble about calling that "the" correct way. The function round(x) can be defined in various standard ways, and different ways can be more useful for different purposes, but there's no sense in which one conventional definition is the unique correct one. http://mathworld.wolfram.com/Nearest...rFunction.html --Gary |
#55
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Runway ID
"Jose" wrote in message ... If you have 0.245, it is 0.24 rounded to hundreths. How is that '5 goes up?' If you actually have 0.245, it is 0.25 rounded to hundredths. However, if you actually have 0.2445, you do NOT have .0245 but a hair less than that. In that case, you don't =have= a five to "go up". If you took a big pile of numbers, rounded them all up, added them, you would have a value that was way off of the true value of the sum. True. But you don't round them all =up=. You round them all (to the nearest). Only the ones that are ...5 and up get rounded up. The others get truncated. Including ...0 which gets its zero truncated (leaving the number unchanged). 0.247 - 0.25 0.255 - 0.26 is that what you mean? That's exactly what I stated. This is correct rounding, but it is it what George stated. He stated "round 1/2 to the EVEN number.", which would imply .245 - .26 which is not true. What =is= true is .245 - .25 .255 - .26 .265 - .27 You don't round them all up? That is exactly what you are doing in your example above. If the digit before the last is even, and the last is five, you round DOWN (0.245 - 0.24) If the digit before the last is odd and the last is five, you round up. (0.255 - 0.26). Bear with me and look at these two examples. The one on the left is a summation of the example you have above. The one on the right is 'my' way. I am just summing the original values and the rounded values at the bottom. .245 - .25 .245 - .24 .255 - .26 .255 - .26 + .265 - .27 + .265 - .26 ------------ ------------ .765 - .78 .765 - .76 You can see where this will get you very quickly if you use the way you propose. Of course our original discussion started off regarding rounding a single number and doing nothing with it, this is just a point of interest. This is not "rounding 1/2 to the even number". Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
#56
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Runway ID
On Mon, 17 Oct 2005 11:03:57 -0400, "Gary Drescher"
wrote: "GeorgeB" wrote in message .. . Jose, you are with the majority, and you are with what it being taught in today's schools until higher level mathematics. The round (exactly) half to the even is correct. George, you're right that rounding is often performed as you say (i.e., exactly half rounds to the nearest even integer), for the reason you say (to avoid statistical biasing). But I'd quibble about calling that "the" correct way. The function round(x) can be defined in various standard ways, and different ways can be more useful for different purposes, but there's no sense in which one conventional definition is the unique correct one. http://mathworld.wolfram.com/Nearest...rFunction.html That, and Mathematica, were what I was going to reference; however, you are correct that I had my head up that smelly place to consider it to be "the" correct way. I've it even further up that smelly place to get off on this when the question was on naming runways based on their magnetic heading ... which is not a constant thing in the short or long term, so what to do with a 5 is absolutely not going to be based on EXACTLY anything. Thanks for saying it so well. George |
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