Altitude is usually measured in height above mean sea level. Unfortunately mean sea level depends on many things including local gravitational anomalies. A big dense rock underground will make the gravitational field locally stronger which means that even if the surface above the rock is mathematically flat, it will appear to have a dip in it where the rock is.
For a GPS to give accurate absolute altitude, it needs to have a map of all the local gravitational anomalies on the planet (or at least in the area it is used in).
OTOH if you are trying to measure changes of height ("Scotland is rising") the absolute zero doesn't matter.
"GPS measurements have also allowed scientists to show that the UK is drifting about 2-3 cm each year in a north-easterly direction."
Of course you need to know what the rest of Europe is doing as well. I suspect, if it is on the same techtonic plate as Europe, then Europe is doing the same thing.
In the first day of the iraque attack, I was traveling from the netherlands to austria, and believe in me, it was not funny to loose the signal and go the wrong way!
There was no interruption to the GPS service during the last Gulf war, at least not here in the UK. If you lost your signal it was more likely for reasons other than the US military switching it off (because they didn't).
Having said that, I can't think of a good reason not to have Galileo since it will double the number of GPS sstellites up there improving accuracy in areas where it is tricky to get a signal (e.g. in built up areas with tall buildings).
Re:Sounds like what C# has that makes it better...
on
Preview of Java 1.5
·
· Score: 1
Hey, why bother with a for loop. Isn't that just compiler bloat? As Kernighan and Ritchie pointed out:
for (i = 0 ; i < SOME_VALUE ; ++i)
{ /* do something */
}
is completely equivalent to
i = 0;
while (i < SOME_VALUE)
{ /* do something */
++i;
}
In fact everything beyond if (...) goto... is theoretically unnecessary.
So when the authors of HTTP 1.1 said "keepalive is deprecated" do you think they meant "we disaprove of its use" or "we think it's a crap idea" (i.e. we belittle it). I think the former, so in this type of context "deprecate" is being used correctly.
I disagree that an influential event needs to destroy the previous world. I also disagree that the www "merely added another medium". After all, the telephone, television, radio, fax, ethernet etc all merely added another medium. Are you suggesting that Alexander Graham Bell does not deserve recognition for the telephone?
The www has revolutionnised the World of on-line information. It's made it infinitely more accessible and at the same time set computer-human interface design back 20 years:)
BTW Einstein's theories of relativity have had almost zero influence on the World. It has no practical applications that I can think of off hand (maybe interplanetary space probes?). The other great scientific theory of the 20th century - quantum mechanics - otoh pervades our every day life. I always think it is fitting that Einstein received the Nobel prize for his description of the photo electric effect (part of quantum mechanics), not relativity since in the long run it has turned out to be far more important.
I'm working on a project where the dev machine is a fast x86 box running SuSE 8.2 . There's one dev box and two of us using it. We both connect to it via our laptops. I have a Ti Powerbook, he has a Win2K Dell.
We can both run KDE and Gnome graphical apps through the X servers installed on our laptops. Your scheme would break that because we'd have to install every damned widget kit for every app that we would want to use.
I agree with that. Following the backward compatibility rule blindly can lead to some serious abortions. In this case, they are sacrificing a nice elegant construct for the person who has a variable named "foreach" (unlikely) and the person who has a variable named "in" (their fault for choosing a stupid non descriptive variable name). A "java 1.4" switch would sort that out plus any reasonable search and replace facility.
If they'd said "i" is now a keyword, that would have been more of a problem.
Funny that, to me as a fairly ancient C coder, ++x looks right and x-- looks right. Why? because in the days when I learnt C, the PDP11 was still a fairly common machine and it has a preincrement indirect mode and a postdecrement indirect mode but not the other way around thus you could save precious cycles using ++x and x--. I realise that now it really doesn't matter.
Having said that, if you're implementing (say) a stack it does matter because if you use
Just get openssl and use it to generate your CA cert and other encryption certs and keys. Then when you want to send encrypted info to other people you can. Of course, there will be all sorts warnings flying about saying "unverifiable certs" *unless* you put your CA cert on a floppy disk and give it to your partners to install in their CA database.
In fact to be truly secure you'd delete all those existing certs from your own CA database (does paying Thawte a stack of cash prove somebody is trustworthy?) and only put in CA certs from people you know and trust in the human sense.
Closed source has more bugs, and the exploits are typically more severe
And what evidence do you have to support this statement? True, lots of bugs have been found in M$ but that's due in part to lots of people looking for them.
Actual turn around time for Closed source is much slower than open source for new features and enhancements
If this were true, open source would be miles ahead of closed source in terms of features by now. This is clearly not the case. Compare Windows XP and an equivalent open source desktop. Which is the most feature rich environment. Consider Oracle or M$ SQL server against any OSS database, which product is the most scalable and has the most features? The only area I see where OSS having an advantage is in the area of bug fixes and that is as much due to OSS developers being prepared to short cut the QA cycle as much as anything.
Closed source hampers IT productivity as the fear of sharing "Intellectual Property" infects and permeates many people that work in closed source environments
Not my in my experience. In fact, due to FUD there is more a fear that "if we use open source, we have to share the IP that we create." Unfair and wrongly informed yes, but true.
Since the first article (well both of them) I have had a chance to download and read the book. I was expecting to be outraged at the authors' lack of knowledge about my favourite operating system but in fact found myself squirming with embarrassment because many of their criticisms seemed to be perfectly valid.
The lack of a proper undelete support and/or versioning, the utter abortion that is/was ufs and its derivatives, the total lack of consistency in commands and their switches, the other abortion that was NFS, the lack of type information for files, the case sensitive file names (actually they didn't mention that one), the other other abortion that was the mail subsystem, the stoneage development environment.
The thing is, in the mid 80s to early 90s when the book was written, I had the opportunity to work on a variety of commercial operating systems and - except in the area of security - they all seemed just as bad or worse.
One particular example that brings tears to my eyes was the OS called MCP that came with Unisys A-series hardware (a stack based machine for which Algol was effectively its assembler language in the same way as C is PDP 11 assembler). The file system didn't corrupt files but there was no undelete facility and if you didn't defrag the disks every other day, the machine ground to a halt because it wasn't clever enough to split files across multiple blocks of free space. If you did defrag the disk the machine ground to a halt because defrag was taking all the IO bandwidth. Its idea of crash diagnostics was also to dump core but it did it to the line printer (in a readable format) not the file system.
Then there was VMS. I remember it being a total pig (but then I was used to Unix - it was probably unfamiliarity). One of the really annoying things was that when you changed something it kept the all the old versions lying around. Eventually, after a heavy debugging session the disk was full.
There were problems with every operating system I ever used which made Unix nice to come back to. It was probably the simplicity of the beast that appealed to me - we examined it in our operating systems course at University and it was easily the most agricultural architecture we looked at (apart from CP/M). I would definitely not have considered it for large scale commercial apps back then. But it was adequate for most small scale things where most other OSs could suck really badly in some areas.
I definitely recommend anybody who is considering developing and distributing apps on any OS to read this book. If you insist on using cryptic error messages, impose stupid restrictions or illogical behaviour, fail to document properly etc etc this is what people will be saying about you.
Exchange does have an SMTP gateway different from IIS as does Groupwise, however, I don't read the letters SMTP in the quote: "the central IT agency for the city currently mandates that we maintain an exchange gateway".
If you configure the WinXP desktop in classic mode, you'll find that it looks and works pretty much the same way as Win95 did 8 years ago apart from som admin type stuff which the users shouldn't be allowed to touch anyway.
Slashdot Mirror
From the article:
GPS measurements have also allowed scientists to show that the UK is drifting about 2-3 cm each year in a north-easterly direction.
Altitude is usually measured in height above mean sea level. Unfortunately mean sea level depends on many things including local gravitational anomalies. A big dense rock underground will make the gravitational field locally stronger which means that even if the surface above the rock is mathematically flat, it will appear to have a dip in it where the rock is.
For a GPS to give accurate absolute altitude, it needs to have a map of all the local gravitational anomalies on the planet (or at least in the area it is used in).
OTOH if you are trying to measure changes of height ("Scotland is rising") the absolute zero doesn't matter.
From the article:
"GPS measurements have also allowed scientists to show that the UK is drifting about 2-3 cm each year in a north-easterly direction."
Of course you need to know what the rest of Europe is doing as well. I suspect, if it is on the same techtonic plate as Europe, then Europe is doing the same thing.
In the first day of the iraque attack, I was traveling from the netherlands to austria, and believe in me, it was not funny to loose the signal and go the wrong way!
There was no interruption to the GPS service during the last Gulf war, at least not here in the UK. If you lost your signal it was more likely for reasons other than the US military switching it off (because they didn't).
Having said that, I can't think of a good reason not to have Galileo since it will double the number of GPS sstellites up there improving accuracy in areas where it is tricky to get a signal (e.g. in built up areas with tall buildings).
Hey, why bother with a for loop. Isn't that just compiler bloat? As Kernighan and Ritchie pointed out:
/* do something */ ;
/* do something */ ; ... is theoretically unnecessary.
for (i = 0 ; i < SOME_VALUE ; ++i)
{
}
is completely equivalent to
i = 0
while (i < SOME_VALUE)
{
++i
}
In fact everything beyond if (...) goto
The American "color" is just as unphonetic as the English "colour". It should be something like "culler". Also, centre/center should start with "S".
The metre and kilogramme were French inventions. I have no problem with sticking with their spelling.
The WGS84 meridian is a bit over 100 metres away from the Greenwich meridian at the moment (at Greenwich).
The WGS84 datum used by GPS is designed such that the average continental drift over the whole Earth wrt to it is zero.
What dictionary did you get that one from?
So when the authors of HTTP 1.1 said "keepalive is deprecated" do you think they meant "we disaprove of its use" or "we think it's a crap idea" (i.e. we belittle it). I think the former, so in this type of context "deprecate" is being used correctly.
I disagree that an influential event needs to destroy the previous world. I also disagree that the www "merely added another medium". After all, the telephone, television, radio, fax, ethernet etc all merely added another medium. Are you suggesting that Alexander Graham Bell does not deserve recognition for the telephone?
:)
The www has revolutionnised the World of on-line information. It's made it infinitely more accessible and at the same time set computer-human interface design back 20 years
BTW Einstein's theories of relativity have had almost zero influence on the World. It has no practical applications that I can think of off hand (maybe interplanetary space probes?). The other great scientific theory of the 20th century - quantum mechanics - otoh pervades our every day life. I always think it is fitting that Einstein received the Nobel prize for his description of the photo electric effect (part of quantum mechanics), not relativity since in the long run it has turned out to be far more important.
I'm working on a project where the dev machine is a fast x86 box running SuSE 8.2 . There's one dev box and two of us using it. We both connect to it via our laptops. I have a Ti Powerbook, he has a Win2K Dell.
We can both run KDE and Gnome graphical apps through the X servers installed on our laptops. Your scheme would break that because we'd have to install every damned widget kit for every app that we would want to use.
His criticism is wrong anyway. "I'd like to be able to propagate exceptions upwards" - you can.
The java.util.logging.Logger class is your friend. Only available since 1.4 I'm afraid.
I agree with that. Following the backward compatibility rule blindly can lead to some serious abortions. In this case, they are sacrificing a nice elegant construct for the person who has a variable named "foreach" (unlikely) and the person who has a variable named "in" (their fault for choosing a stupid non descriptive variable name). A "java 1.4" switch would sort that out plus any reasonable search and replace facility.
If they'd said "i" is now a keyword, that would have been more of a problem.
The PDP11 had a direct machine language equivalent to
; ;
*x-- and *++x but not the other way around as long as x was a register variable.
e.g.
register int x
y = *++x
looked something like (if x is in r1):
move +(r1), y
Apologies if I've got the syntax wrong...
"I came, I saw, I conquered"
Oh look: noun-verb, noun-verb, noun-verb.
Funny that, to me as a fairly ancient C coder, ++x looks right and x-- looks right. Why? because in the days when I learnt C, the PDP11 was still a fairly common machine and it has a preincrement indirect mode and a postdecrement indirect mode but not the other way around thus you could save precious cycles using ++x and x--. I realise that now it really doesn't matter.
Having said that, if you're implementing (say) a stack it does matter because if you use
*x-- = someValue
to push items on the stack, you must use
someValue = *++x
to get things off.
Just get openssl and use it to generate your CA cert and other encryption certs and keys. Then when you want to send encrypted info to other people you can. Of course, there will be all sorts warnings flying about saying "unverifiable certs" *unless* you put your CA cert on a floppy disk and give it to your partners to install in their CA database.
In fact to be truly secure you'd delete all those existing certs from your own CA database (does paying Thawte a stack of cash prove somebody is trustworthy?) and only put in CA certs from people you know and trust in the human sense.
Closed source has more bugs, and the exploits are typically more severe
And what evidence do you have to support this statement? True, lots of bugs have been found in M$ but that's due in part to lots of people looking for them.
Actual turn around time for Closed source is much slower than open source for new features and enhancements
If this were true, open source would be miles ahead of closed source in terms of features by now. This is clearly not the case. Compare Windows XP and an equivalent open source desktop. Which is the most feature rich environment. Consider Oracle or M$ SQL server against any OSS database, which product is the most scalable and has the most features? The only area I see where OSS having an advantage is in the area of bug fixes and that is as much due to OSS developers being prepared to short cut the QA cycle as much as anything.
Closed source hampers IT productivity as the fear of sharing "Intellectual Property" infects and permeates many people that work in closed source environments
Not my in my experience. In fact, due to FUD there is more a fear that "if we use open source, we have to share the IP that we create." Unfair and wrongly informed yes, but true.
Newsflash: Labour is not an insignificant cost in any enterprise computer system.
Other newsflash: many companies have site wide Oracle licences so adding extra applications can be free.
What is it? do you have a web link?
I was going to reply to this and say you're supposed to pronounce the "G" but having looked it up in my dictionary, I found that it is a silent G.
OTOH GNU as in Free Software is an acronym made up by Richard Stallman so I guess he can specify any pronunciation he likes.
Anyway, your typical Linux distro does not contain just Gnu userland tools so it's ridiculous to call it Gnu/Linux nowadays.
Since the first article (well both of them) I have had a chance to download and read the book. I was expecting to be outraged at the authors' lack of knowledge about my favourite operating system but in fact found myself squirming with embarrassment because many of their criticisms seemed to be perfectly valid.
The lack of a proper undelete support and/or versioning, the utter abortion that is/was ufs and its derivatives, the total lack of consistency in commands and their switches, the other abortion that was NFS, the lack of type information for files, the case sensitive file names (actually they didn't mention that one), the other other abortion that was the mail subsystem, the stoneage development environment.
The thing is, in the mid 80s to early 90s when the book was written, I had the opportunity to work on a variety of commercial operating systems and - except in the area of security - they all seemed just as bad or worse.
One particular example that brings tears to my eyes was the OS called MCP that came with Unisys A-series hardware (a stack based machine for which Algol was effectively its assembler language in the same way as C is PDP 11 assembler). The file system didn't corrupt files but there was no undelete facility and if you didn't defrag the disks every other day, the machine ground to a halt because it wasn't clever enough to split files across multiple blocks of free space. If you did defrag the disk the machine ground to a halt because defrag was taking all the IO bandwidth. Its idea of crash diagnostics was also to dump core but it did it to the line printer (in a readable format) not the file system.
Then there was VMS. I remember it being a total pig (but then I was used to Unix - it was probably unfamiliarity). One of the really annoying things was that when you changed something it kept the all the old versions lying around. Eventually, after a heavy debugging session the disk was full.
There were problems with every operating system I ever used which made Unix nice to come back to. It was probably the simplicity of the beast that appealed to me - we examined it in our operating systems course at University and it was easily the most agricultural architecture we looked at (apart from CP/M). I would definitely not have considered it for large scale commercial apps back then. But it was adequate for most small scale things where most other OSs could suck really badly in some areas.
I definitely recommend anybody who is considering developing and distributing apps on any OS to read this book. If you insist on using cryptic error messages, impose stupid restrictions or illogical behaviour, fail to document properly etc etc this is what people will be saying about you.
Exchange does have an SMTP gateway different from IIS as does Groupwise, however, I don't read the letters SMTP in the quote: "the central IT agency for the city currently mandates that we maintain an exchange gateway".
If you configure the WinXP desktop in classic mode, you'll find that it looks and works pretty much the same way as Win95 did 8 years ago apart from som admin type stuff which the users shouldn't be allowed to touch anyway.