Re: [Flightgear-devel] Re: Environment subsystem status
On Thu, 16 May 2002, Julian Foad wrote: John Wojnaroski wrote: I recall reading an article several years ago in a flying mag (can't remember exactly where or when) on someone's proposal to change the number of degrees on the compass from 360 to 400. ... Have you noticed Deg/Rad/Grad or DRG on every scientific calculator? Those are Grads. I've heard that the military use them ... but I haven't seen any evidence of it. No, the military use mils - 6400 of em to 360 degrees AFAICR. -- Jon StockillPublic Key: C3749C06 [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* [EMAIL PROTECTED] -- Thursday 16 May 2002 16:25: After reading this story I can't help but note another advantage of SI: easy-to-remember figures. 0 degrees celsius is where water freezes, 100 degrees is where water boils, and a liter of water weighs one kilogram. *) [...] *) I know, its *mass* is a kilogram. It weighs about 9.81 Newtons. ... and the SI unit for temperature is Kelvin, no? :- m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Melchior FRANZ -- Thursday 16 May 2002 16:35: ... and the SI unit for temperature is Kelvin, no? :- OK, OK. Degree Celsius is a so-called Derived SI Unit. :-) m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Melchior FRANZ writes: * [EMAIL PROTECTED] -- Thursday 16 May 2002 16:25: After reading this story I can't help but note another advantage of SI: easy-to-remember figures. 0 degrees celsius is where water freezes, 100 degrees is where water boils, and a liter of water weighs one kilogram. *) [...] *) I know, its *mass* is a kilogram. It weighs about 9.81 Newtons. ... and the SI unit for temperature is Kelvin, no? :- So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities[EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
On Thu, 16 May 2002 09:48:06 -0500 (CDT) Curtis L. Olson [EMAIL PROTECTED] wrote: ... and the SI unit for temperature is Kelvin, no? :- So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) One of the worst things about metric, though, is the 100 minute hours - which isn't really an hour, but a hecto-moment. There are 100 days in a metric year, so the seasons are on a rotating basis. The upside is that we'll all live to be very old in metric terms. :-P Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Curtis L. Olson -- Thursday 16 May 2002 16:48: Melchior FRANZ writes: ... and the SI unit for temperature is Kelvin, no? :- So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) There's no contradiction, as far as I see: degree comes from gradum (step) and is unit-less, like percent. Only degree Celsius is a unit. m. :-) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Jon S Berndt wrote: On Thu, 16 May 2002 09:48:06 -0500 (CDT) Curtis L. Olson [EMAIL PROTECTED] wrote: ... and the SI unit for temperature is Kelvin, no? :- So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) One of the worst things about metric, though, is the 100 minute hours - which isn't really an hour, but a hecto-moment. There are 100 days in a metric year, so the seasons are on a rotating basis. The upside is that we'll all live to be very old in metric terms. Sorry, but you didn't understand Metric. They come in 1000. So 1 Millenium = 1 000 Years = 1 000 000 Months = 1 000 000 000 Days = 1 000 000 000 000 Hours = 1 000 000 000 000 000 Seconds = 1 000 000 000 000 000 000 milli seconds ;-) So what is the SI unit for direction/heading? There's no unit for direction/heading. There's no need for it. There's also no unit for pendulum/not-beeing-in-the-middle. What you need is a normative direction (e.g. noth) and an angle to it. That unit is 1 rad = 1 m/m = 360/2pi deg a derivate of the basic SI unit meter. (Note: degrees are still valid as they are *internationally* well known. slugs aren't) CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) I recall reading an article several years ago in a flying mag (can't remember exactly where or when) on someone's proposal to change the number of degrees on the compass from 360 to 400. Seems they had a problem computing reciprocals using 180 ;-) The author saw the change as a minor effort to simple repaint all the runway numbers and change compass card faceplates!! Regards John W. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
John Wojnaroski writes: So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) I recall reading an article several years ago in a flying mag (can't remember exactly where or when) on someone's proposal to change the number of degrees on the compass from 360 to 400. Seems they had a problem computing reciprocals using 180 ;-) The author saw the change as a minor effort to simple repaint all the runway numbers and change compass card faceplates!! And if the automake/autoconf development team were in charge they would do it! Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities[EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
John Wojnaroski wrote: So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) I recall reading an article several years ago in a flying mag (can't remember exactly where or when) on someone's proposal to change the number of degrees on the compass from 360 to 400. Seems they had a problem computing reciprocals using 180 ;-) The author saw the change as a minor effort to simple repaint all the runway numbers and change compass card faceplates!! You are talking here about a gon wich is defines as 1 gon = pi/200 rad I've heard that those are used for measuring the landscape. But they are as invalid for SI as deg is. And they lack the common use that deg has. So we can forget them very fast. (If someone wants to experiment with them: the standard Casio calculators can be switched into that mode for the trig functions... I think it's called gra on them) CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
John Wojnaroski wrote: I recall reading an article several years ago in a flying mag (can't remember exactly where or when) on someone's proposal to change the number of degrees on the compass from 360 to 400. ... Have you noticed Deg/Rad/Grad or DRG on every scientific calculator? Those are Grads. I've heard that the military use them ... but I haven't seen any evidence of it. - Julian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Christian said: (Note: degrees are still valid as they are *internationally* well known. slugs aren't) Yes they are ... each country's definition depends on local climate and fauna, ranging from one gram, through one ounce to as high as one pound. I don't know of a slug being one kilogram but wouldn't be especially surprised. 8-) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Alex Perry wrote: Christian said: (Note: degrees are still valid as they are *internationally* well known. slugs aren't) Yes they are ... each country's definition depends on local climate and fauna, ranging from one gram, through one ounce to as high as one pound. I don't know of a slug being one kilogram but wouldn't be especially surprised. If you go back to the middle ages: that's true. And it was even worse as each town had its own measurements (and sometimes names; feet is one of the more common ones). But: today it's different. The majority of all countries settled on the SI system. CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Curtis L. Olson wrote: So what is the SI unit for direction/heading? Certainly they wouldn't overload unit names, right? :-) Oooh, here's a good one! There *are* no unit names for angles. Angles are unitless numbers. So to be strict, the SI unit for heading must be the radian. :) FWIW, angles and computers don't mix well (tan(90) == Inf and all that). YASim does all its math in cartesian space, and converts to angles only at the output stage. Here's one such bug I discovered recently: turn on the HUD, and enter a steady turn. When your heading gets near 0 or 180, the pitch ladder just disappears. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com Men go crazy in conflagrations. They only get better one by one. - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
On Thu, 16 May 2002 18:46:16 +0200 Christian Mayer [EMAIL PROTECTED] wrote: Christian said: (Note: degrees are still valid as they are *internationally* well known. slugs aren't) Alex responded: Yes they are ... each country's definition depends on local climate and fauna, ranging from one gram, through one ounce to as high as one pound. I don't know of a slug being one kilogram but wouldn't be especially surprised. Christian replied, obliviously: If you go back to the middle ages: that's true. And it was even worse as each town had its own measurements (and sometimes names; feet is one of the more common ones). Jon replies: would it help to say that a one kilogram slug with salt sprinkled on it and allowed to sit in the sunlight for a day will be considerably less than one kilogram at the end of that day. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Julian Foad -- Thursday 16 May 2002 18:27: Have you noticed Deg/Rad/Grad or DRG on every scientific calculator? Those are Grads. I've heard that the military use them ... but I haven't seen any evidence of it. Infantery and artillery use 0-6400 mil (called Strich over here), NBC also uses these and additionally 0-360 (for meteorolgy issues). I don't know if we are anywhere using 0-400, but it may well be.:-) Cpt. m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Christian Mayer wrote: (Note: degrees are still valid as they are *internationally* well known. slugs aren't) Actually, there's a very good reason why we use a 360 degree circle. This number has loads of small integer divisors. What's the inner angle between the walls of a 4-sided room? 90 degrees, of course. You can do it in your head for 3, 4, 5, 6, 8, 9, 10, 12, ... In the days before calculators, this was really important. This same logic is why we have 60 minutes per hour and 24 hours per day. It might make more logical sense (well, to species with 10 digits on their hands) to use 100 and 10, perhaps, but try dividing those into three parts. Dolly Parton would have had a hard time making Workin' 4:33:33 to 7:33:33 into a hit song. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com Men go crazy in conflagrations. They only get better one by one. - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
Andy Ross wrote: Christian Mayer wrote: (Note: degrees are still valid as they are *internationally* well known. slugs aren't) Actually, there's a very good reason why we use a 360 degree circle. This number has loads of small integer divisors. ...In the days before calculators, this was really important. This same logic is why we have 60 minutes per hour and 24 hours per day. IIRC, 360 degrees is Babylonian in origin. For some reason multiples of 12 and the number 360 was very important to them. The multiple integer relationships not being a bad thought about why. Twelve also shows up strongly as an important number not only for them, but, for those familiar with the Bible, the ancient Hebrews as well - possibly by association. For example, in Jewish numerology, 3 stands for God, 4 for Heaven and 12 (3 x 4) for God in Heaven. (Don't ask why - I haven't a clue.) Imperial units also have an interesting relationship to some of the units used by the Egyptians. They used a foot of very close to 300 mm (11.8 inches) and the cubit of 450 mm (17.7 inches). The Romans, for some reason changed the latter to 16. Lacking an easy to define base standard, the problem of uniform measurements was never solved until long after the French gave us the metric system based upon latitude. Finally, (under Napoleon ?) the French tried to reform the calendar and make that metric or logical as well. Even with the Committee for Public Safety available to enforce it, they couldn't get that system to catch on. Never underestimate the power of tradition. Regards, Charlie H. -- C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg. - Bjarne Stroustrup ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Christian Mayer -- Wednesday 15 May 2002 17:39: David Megginson wrote: /environment/pressure-inhg /environment/density-sea-level-slugft3 [...] But I'm really concerned that these values aren't in SI units. So most of the world (except the US and perhaps a few other countries) can't use those units anymore without big research (aks somebody around here what a 'slug' is... [*I* know it, but that doesn't count]). ACK! I don't. Given that 90 percent of the world and 100 percent of the science community use SI units, inhg and slugft3 make as much sense as 5 bananas long, 4 coconuts heavy, ... no actually, they make less sense. I =know= how long a banana typically is. ;-) m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
On Wednesday 15 May 2002 12:12 pm, Melchior FRANZ wrote: * Christian Mayer -- Wednesday 15 May 2002 17:39: David Megginson wrote: /environment/pressure-inhg /environment/density-sea-level-slugft3 [...] But I'm really concerned that these values aren't in SI units. So most of the world (except the US and perhaps a few other countries) can't use those units anymore without big research (aks somebody around here what a 'slug' is... [*I* know it, but that doesn't count]). ACK! I don't. Given that 90 percent of the world and 100 percent of the science community use SI units, inhg and slugft3 make as much sense as 5 bananas long, 4 coconuts heavy, ... no actually, they make less sense. I =know= how long a banana typically is. ;-) m. You must have went to the same uni as the Professor on Gilligans Island ;) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Andy Ross -- Wednesday 15 May 2002 18:44: Typical (North American, anyway) altimeters still report feet, VSI indicators read in fpm, etc... Same here. But please don't tell me that US meteorologist work with slugft3. PS: I withdraw my estimatian that 90% of the world are using SI-units. I bet the Chinese have some silly non-standard units on their own. :-P m. -- Computers in the future may perhaps only weigh 1.5 tons -- Magazine Popular Mechanics, 1949 ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
--- Melchior FRANZ [EMAIL PROTECTED] wrote: * Andy Ross -- Wednesday 15 May 2002 18:44: Typical (North American, anyway) altimeters still report feet, VSI indicators read in fpm, etc... Same here. But please don't tell me that US meteorologist work with slugft3. Don't be so quick to slight slugs, feet, etc. The fundamental units of each system are ***arbitrarily*** defined and, because of that each system requires everybody to agree on a common set of arbitrary definitions. The only real advantage that SI has over any other is that scaling is done in powers of ten and a system of prefixes define those scales. So: Meters are not better than feet, just different. Kilograms are not better than slugs, just different. (yes, SI defines a scaled unit as the standard for mass) Liters are not better than gallons, just different. etc. etc. etc. PS: I withdraw my estimatian that 90% of the world are using SI-units. I bet the Chinese have some silly non-standard units on their own. :-P m. -- Computers in the future may perhaps only weigh 1.5 tons -- Magazine Popular Mechanics, 1949 ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel __ Do You Yahoo!? LAUNCH - Your Yahoo! Music Experience http://launch.yahoo.com ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Re: Environment subsystem status
* Tony Peden -- Wednesday 15 May 2002 19:47: Meters are not better than feet, just different. [...] Yes, obviously. It's the words international and standard that make the difference. But these a quite essential details. And it would be quite poor if US universities taught anything else than SI units. Except aeronautics, that is. And that's another hard to deny detail: These weird anachronistic imperial units =are= some international standard in this area ... (only). And this will hardly change any time soon. Moving over is simply too dangerous. It's like convincing Britains to drive at the right side. (Well, we all know, that the left side is the right side, anyway. ;-) m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
On Wed, May 15, 2002 at 10:47:03AM -0700, Tony Peden wrote: --- Melchior FRANZ [EMAIL PROTECTED] wrote: * Andy Ross -- Wednesday 15 May 2002 18:44: Typical (North American, anyway) altimeters still report feet, VSI indicators read in fpm, etc... Same here. But please don't tell me that US meteorologist work with slugft3. Don't be so quick to slight slugs, feet, etc. The fundamental units of each system are ***arbitrarily*** defined and, because of that each system requires everybody to agree on a common set of arbitrary definitions. I wish it was that simple. After moving to Canada, I was doing an off the cuff calculation and said '1 gallon of water is roughly 8lbs'. Imagine my surprise when everyone in the room disagreed with me, saying a gallon weighs 10lb. All was made well when I was reminded that Canadians use imperial gallons. Aaargh. SI is a real international standard, while 'english' units are just a mess. Of course, I am constantly reminded of my US background when I tell the Scouts in my troop to cut a 6' piece of line and get blank stares. They want me to say 2m. At the same time almost none of them can tell me their 'weight' in kilograms. -- James (Jay) Treacy [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[OT] Re: [Flightgear-devel] Re: Environment subsystem status
James A. Treacy writes: Of course, I am constantly reminded of my US background when I tell the Scouts in my troop to cut a 6' piece of line and get blank stares. They want me to say 2m. At the same time almost none of them can tell me their 'weight' in kilograms. I remember when I was in England at a youth camp we were playing some game where the kids had to go around and find the leaders and get them to sign off on their sheet. The big trick was that the kids had to find the leaders in ascending order. I had the joy of being #2. So as soon as the first couple kids found me, a very large, vicious, and demanding mob quickly began to form around me all of them shoving little papers and pencils in my face. It was very traumatic. :-) I started yelling, Hey! Everyone get in a line or I'm not signing anyone's paper. This was met with continued and even more frantic mobbing. After yelling my ultimatum a couple more times with no change in the mob behavior, a light bulb went off. I yelled Oi! Queue up! and almost instantly the insane mob transformed itself into a perfectly calm, well behaved line, er, uh I mean queue. James mentioned line and blank stares so I thought this would be a similar story ... :-) Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities[EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
James A. Treacy wrote: SI is a real international standard, while 'english' units are just a mess. Of course, I am constantly reminded of my US background when I tell the Scouts in my troop to cut a 6' piece of line and get blank stares. They want me to say 2m. At the same time almost none of them can tell me their 'weight' in kilograms. And the length of people is also measures in feet, isn't it? At least in New Zealand it's the same. But that'll go away eventually. In Germany is the generation of my parents still asking for a pound (= 500g = 1/2 kg) of something in the shop. But the people of my generation is using the official units. Anyway to come back to the thread: isn't your story a proof that SI should be used? CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Environment subsystem status
On Thu, May 16, 2002 at 12:07:21AM +0200, Christian Mayer wrote: Anyway to come back to the thread: isn't your story a proof that SI should be used? Proof? That's a bit strong. I'm somewhat torn on this issue. Having grown up using english units, I have a (small) soft spot for them. On the other hand, SI units are more logical and reduce the chance for errors. Also, being a volunteer group, it is difficult to impose a rule such as 'thou shalt use SI'. If anyone cares about the opinion of a non-coder (on this project) a reasonable solution to the issue of units could be that a piece of code must provide an SI interface. This way parts of the project, such as jsb, can use whatever units they want internally as long as they provide an SI interface. They are, of course, free to provide other interfaces if they choose. -- James (Jay) Treacy [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
