There's surprising variability in text book quality. Some are written for scientific rigor, precision and conciseness at the expense of readability and accessibility. Others give a little on using the precise scientific terms at every turn, focusing instead on being approachable and accurate. For example, consider the following paragraph from my Thermodynamics book, introducing the 2nd law:
An object at an elevated temperature Ti placed in contact with atmospheric air at temprature T0 would eventually cool to the temperature of its much larger surroundings, as illustrated in Fig. 5.1a. In conformity with the conservation of energy principle the decrease in internal energy of the body would appear as an increase in the internal energy of the surroundings. The reverse process would not take place spontaneously, even though energy could be conserved: The internal energy of the surroundigns would not decrease spontaneously while the body warmed from T0 to its initial temperature.
That was from Fundamentals of Engineering Thermodynamics by Moran and Shapiro, 2nd Ed., p 160. I took this as an electrical engineering student many years ago (1995, I believe).
Some years later, my girlfriend at the time was studying toward her mechanical engineering degree. Her textbook (which I don't have handy), introduced the topic in what I thought was a much more approachable manner. Paraphrasing, it went something like this:
Consider, for example, a cup of hot coffee placed in a room at room temperature. As you would expect, the cup of coffee will eventually cool to the temperature of the room. In the process, it will transfer energy to the air in the room and energy is conserved. The reverse process, spontaneously heating the cup of coffee by drawing energy from the cool room would not occur, even though energy would still be conserved.
Both are engineering texts covering the same material, but with completely different treatments. Both cover the same range of topics, the same steam tables, the same cycles... everything. But, which text book is more accessible? Which text book is more effective? All I know is I had a really hard time in Thermo, whereas she picked it up very quickly. (I did manage to eke out a B, but she aced it as I recall.) Some of it's aptitude—we each picked our disciplines for a reason—but a big factor is accessibility. I found myself understanding Thermo much better than I had, just reading portions of her book.
And that's kinda how it goes. Some classes have impenetrable texts, others don't. These days, the wealth of online materials is astonishing compared to what I had when I was in school—1992 - 1996—and so that helps a lot.
The main thing is to have fun. If you're not having fun doing engineering, then maybe another line of work is better for you. Sure, the projects are challenging, the homework is difficult and often draining, but it's all worth it when you get to the other end and see things come to life. If that doesn't make it worth it to you, then perhaps it's not your field.
XP did that to me on a machine I recently built. (I built it solely to run XP, because I have some embedded development software that only runs on Windows.)
It'd always fail in the same file. Turned out to be faulty RAM. I removed the RAM stick and everything was fine. I exchanged the RAM for a non-faulty stick, and everything was still fine.
As best as I can tell, the RAM fault only got triggered when decompressing a sufficiently large file, which is why it consistently labeled the same file "corrupt."
At work, they generate passwords FOR us, and then we get to pick out of a list which one we want. 8 characters, alphanumeric, mixed case. They expire every 6 months or so. So, I end up with passwords like f3nqDe4C* and the like.
I usually DO have to write it on a Post-It to remember the MixEd cAsE for at least a couple days, but that stays in my wallet, and gets thrown out pretty quickly. Such fun.
--Joe
* Not an actual password, but similar in character to passwords I've had.
You'll need to continually expend energy so you don't fall into the sun. Gravity works in all directions, not just in the plane that contains the planets.
If you're on a private, trusted network and you're using SSH mainly as an RSH replacement, it makes total sense. For example, I don't see a need to actually AES encrypt communication between my computer and my wife's computer on my home's LAN. But, I do scp files between them from time to time.
I could install RSH and friends, but SSH tends to have better error checking (e.g. when wielding globs and such, or when it comes to getting tripped up on noisy login scripts) and is all around nicer.
Part of the scaling problem is due the amount of buffering relative to the bandwidth-delay product. So really, they could just look for pairs of systems with really, really, high ping times. Deep Space Network anyone?
BDP is the bandwidth-delay product. BDP is one of the main things these patches address. Loopback has very, very little delay. You could, I suppose, add artificial delay over loopback, but now you're diverging further from the actual deployment scenario.
The other thing is that when sender and receiver are the same host, you don't engage the full network stack (no ethernet queuing, for example, no dropped packets, etc. etc.), so you don't find out all the curve balls that TCP/IP will throw you.
And yet another thing is that sender and receiver will compete for the same CPUs, and so whatever upper CPU bound you have with separate sender and receiver, you'll be at roughly half that (assuming send and receive are balanced) when both are on the same machine.
My, what tact! I'm sure you'll win friends and influence people that way, and have nothing but a direct path to the top! Combine that with your unabashed forwardness and your knack for standing behind your words, and wow... you're a force to be reckoned with!
FWIW, I'm an engineer that gets to deal with the practical side of IP and IP law, and as such mostly has to wrangle with patents and (to a thankfully lesser extent) licensing. Sure, I'm not actually a lawyer, but I do work with our patent attorneys and I am a member of our company's patent committee. (This means I get to review disclosed inventions to determine patentability before they move to the next step, which is filing.)
I'll be quite honest. I was surprised by the special laws regarding mask work. They are very similar to copyright, and in their absence, I can envision companies using or attempting to use copyright law in the manner I suggested. In the end, the effect is similar, but the term is dramatically shorter. This makes sense, given the nature of silicon. By the time a mask work protection expires, you can fit 1.5 orders of magnitude more transistors in the same space. (1.5 orders of magnitude is 10*sqrt(10) which is not far from 2^5 = 32.) Heck, these protections appear in Title 17 (the Copyright Act) and are enforced by the Copyright Office, so....
The main thing, though, is that it's not covered solely by patent law, which was my main objection.
FWIW, mask work is defined under the Copyright Act and is administered by the Copyright Office (as opposed to the USPTO), so you can understand how one might get confused.:-)
As I said in my other followup, mea culpa. I learn something new every day!
See, I *knew* it couldn't be solely protected by patents. I'm not an IP lawyer, but I do work closely with them regularly. I'm on our company's patent committee, and so I have a pretty good idea of what patents are meant to cover and what they're not meant to cover.
I had never heard of the separate "mask work" protection. Interesting stuff.
The implemented logic is patentable (as long as it meets the other criteria, such as novelty, non-obviousness, and lack of prior art). I can make a new chip using the same logic as the current one and, if it's a different layout, then I only have to worry about patents. If the logic is patented, I'd run afoul of the patents.
Well, ordinarily I'd agree with you, but a freshly started Firefox with no open pages already has all that mapped memory that's not part of the RSS. That seems odd. Maybe it's all the libraries it has mapped. Indeed, looking at/proc/<pid>/maps, only about 530MB of the over 1GB it currently has mapped is writable. The rest of the pages are mapped read-only or no-access.
In fact, there's a whopping 396,472,320 of pages with entries like this in/proc/<pid>/maps for Firefox. Entries that look like this:
Aha... That appears to be some largish dead-zone between the read-execute code area and the read-write data area. That's the missing 400M. (Well, the sum of all those no-access maps.) And here I thought it was a shared memory segment w/ X. Thanks for forcing me to take a deeper look. I learn something new every day.
The first number suggests Firefox is taking nearly 1GB, but 512MB of that is just the X mapping my video card, I think. The second number shows it clearly taking around 450M.
On my box it's currently taking around 450MB. I usually kill it when it gets to around 700MB. Maybe it's because I use GMail and Yahoo! Mail open all the time?
Slashdot Mirror
There's surprising variability in text book quality. Some are written for scientific rigor, precision and conciseness at the expense of readability and accessibility. Others give a little on using the precise scientific terms at every turn, focusing instead on being approachable and accurate. For example, consider the following paragraph from my Thermodynamics book, introducing the 2nd law:
That was from Fundamentals of Engineering Thermodynamics by Moran and Shapiro, 2nd Ed., p 160. I took this as an electrical engineering student many years ago (1995, I believe).
Some years later, my girlfriend at the time was studying toward her mechanical engineering degree. Her textbook (which I don't have handy), introduced the topic in what I thought was a much more approachable manner. Paraphrasing, it went something like this:
Both are engineering texts covering the same material, but with completely different treatments. Both cover the same range of topics, the same steam tables, the same cycles... everything. But, which text book is more accessible? Which text book is more effective? All I know is I had a really hard time in Thermo, whereas she picked it up very quickly. (I did manage to eke out a B, but she aced it as I recall.) Some of it's aptitude—we each picked our disciplines for a reason—but a big factor is accessibility. I found myself understanding Thermo much better than I had, just reading portions of her book.
And that's kinda how it goes. Some classes have impenetrable texts, others don't. These days, the wealth of online materials is astonishing compared to what I had when I was in school—1992 - 1996—and so that helps a lot.
The main thing is to have fun. If you're not having fun doing engineering, then maybe another line of work is better for you. Sure, the projects are challenging, the homework is difficult and often draining, but it's all worth it when you get to the other end and see things come to life. If that doesn't make it worth it to you, then perhaps it's not your field.
--JoeI know a couple that celebrates two anniversaries on leap year, because they
Clever!
Somewhere around 1 / (thickness of a human hair).
XP did that to me on a machine I recently built. (I built it solely to run XP, because I have some embedded development software that only runs on Windows.)
It'd always fail in the same file. Turned out to be faulty RAM. I removed the RAM stick and everything was fine. I exchanged the RAM for a non-faulty stick, and everything was still fine.
As best as I can tell, the RAM fault only got triggered when decompressing a sufficiently large file, which is why it consistently labeled the same file "corrupt."
If this happens, don't make anyone angry. You wouldn't like them when they're angry.
--JoeSlashdot has ads?
At work, they generate passwords FOR us, and then we get to pick out of a list which one we want. 8 characters, alphanumeric, mixed case. They expire every 6 months or so. So, I end up with passwords like f3nqDe4C* and the like.
I usually DO have to write it on a Post-It to remember the MixEd cAsE for at least a couple days, but that stays in my wallet, and gets thrown out pretty quickly. Such fun.
--Joe* Not an actual password, but similar in character to passwords I've had.
You'll need to continually expend energy so you don't fall into the sun. Gravity works in all directions, not just in the plane that contains the planets.
Gravity sucks though....
So what happens again when our view of Titan is occluded by the Sun?
If you're on a private, trusted network and you're using SSH mainly as an RSH replacement, it makes total sense. For example, I don't see a need to actually AES encrypt communication between my computer and my wife's computer on my home's LAN. But, I do scp files between them from time to time.
I could install RSH and friends, but SSH tends to have better error checking (e.g. when wielding globs and such, or when it comes to getting tripped up on noisy login scripts) and is all around nicer.
Part of the scaling problem is due the amount of buffering relative to the bandwidth-delay product. So really, they could just look for pairs of systems with really, really, high ping times. Deep Space Network anyone?
BDP is the bandwidth-delay product. BDP is one of the main things these patches address. Loopback has very, very little delay. You could, I suppose, add artificial delay over loopback, but now you're diverging further from the actual deployment scenario.
The other thing is that when sender and receiver are the same host, you don't engage the full network stack (no ethernet queuing, for example, no dropped packets, etc. etc.), so you don't find out all the curve balls that TCP/IP will throw you.
And yet another thing is that sender and receiver will compete for the same CPUs, and so whatever upper CPU bound you have with separate sender and receiver, you'll be at roughly half that (assuming send and receive are balanced) when both are on the same machine.
--JoeIf it weren't for you pesky kids, I'd be able to surf in peace with my Difference Engine.
Midgets?
My, what tact! I'm sure you'll win friends and influence people that way, and have nothing but a direct path to the top! Combine that with your unabashed forwardness and your knack for standing behind your words, and wow... you're a force to be reckoned with!
FWIW, I'm an engineer that gets to deal with the practical side of IP and IP law, and as such mostly has to wrangle with patents and (to a thankfully lesser extent) licensing. Sure, I'm not actually a lawyer, but I do work with our patent attorneys and I am a member of our company's patent committee. (This means I get to review disclosed inventions to determine patentability before they move to the next step, which is filing.)
I'll be quite honest. I was surprised by the special laws regarding mask work. They are very similar to copyright, and in their absence, I can envision companies using or attempting to use copyright law in the manner I suggested. In the end, the effect is similar, but the term is dramatically shorter. This makes sense, given the nature of silicon. By the time a mask work protection expires, you can fit 1.5 orders of magnitude more transistors in the same space. (1.5 orders of magnitude is 10*sqrt(10) which is not far from 2^5 = 32.) Heck, these protections appear in Title 17 (the Copyright Act) and are enforced by the Copyright Office, so....
Yeah, though I did follow up with a correction. Granted, the masks I remembered seeing © on were prior to the 1984 law that made explicit that masks are not covered under copyright, and established separate protection for them. (And here I thought it was just because newer masks had such small features that the copyright designation becomes harder to see.) Of course, in those early days of computing, nobody was sure what copyright actually covered. Modern masks, such as this one do have the circle-M on them.
The main thing, though, is that it's not covered solely by patent law, which was my main objection.
FWIW, mask work is defined under the Copyright Act and is administered by the Copyright Office (as opposed to the USPTO), so you can understand how one might get confused. :-)
As I said in my other followup, mea culpa. I learn something new every day!
--JoeSee, I *knew* it couldn't be solely protected by patents. I'm not an IP lawyer, but I do work closely with them regularly. I'm on our company's patent committee, and so I have a pretty good idea of what patents are meant to cover and what they're not meant to cover.
I had never heard of the separate "mask work" protection. Interesting stuff.
*sigh*
The implemented logic is patentable (as long as it meets the other criteria, such as novelty, non-obviousness, and lack of prior art). I can make a new chip using the same logic as the current one and, if it's a different layout, then I only have to worry about patents. If the logic is patented, I'd run afoul of the patents.
Layout, though, is not a patent issue unless the layout is integral to the invention. I had asserted that layout was covered by copyright, but I was wrong. Both of us were wrong, actually, but it appears I was closer. According to Wikipedia, layouts enjoy a copyright-like protection that is separate of regular copyright law or patents, but mainly because copyright law isn't fully appropriate/adequate. There is a separate "mask work" protection that is very similar to copyright, minus the fair use exception and with a shorter term (10 years). I'm guessing that the die photos I've seen with the © are pre-1984 then. I've seen more recent photos with the (M) they mention.
Mea culpa. Learn something new every day.
--JoeYou can also copyright the masks and layouts of the transistors. Board artwork for circuit boards has long been held as copyrightable, and the miniaturized artwork that exists on a CPU is no different. If you look at closeups of dies, you will see a © symbol occasionally, such as on this one.
A wise person once said to me: "When Coke and Pepsi fight, who loses? Royal Crown."
When #1 and #2 fight, invariably #3 loses.
--JoeWell, ordinarily I'd agree with you, but a freshly started Firefox with no open pages already has all that mapped memory that's not part of the RSS. That seems odd. Maybe it's all the libraries it has mapped. Indeed, looking at /proc/<pid>/maps, only about 530MB of the over 1GB it currently has mapped is writable. The rest of the pages are mapped read-only or no-access.
In fact, there's a whopping 396,472,320 of pages with entries like this in /proc/<pid>/maps for Firefox. Entries that look like this:
2aaab0c62000-2aaab0c98000 r-xp 00000000 03:02 5458533 /usr/lib/libnspr4.so.0d /usr/lib/libnspr4.so.0d /usr/lib/libnspr4.so.0d
2aaab0c98000-2aaab0e97000 ---p 00036000 03:02 5458533
2aaab0e97000-2aaab0e9a000 rw-p 00035000 03:02 5458533
Aha... That appears to be some largish dead-zone between the read-execute code area and the read-write data area. That's the missing 400M. (Well, the sum of all those no-access maps.) And here I thought it was a shared memory segment w/ X. Thanks for forcing me to take a deeper look. I learn something new every day.
--JoeHow many windows / tabs do you tend to have open, and how often do you restart the browser? Also, what OS?
Here's the output of ps on my 64-bit Ubuntu 7.04 box, running Ubuntu's Firefox package:
im14u2c 2527 6.1 11.2 987640 454116 ? Sl Feb07 176:30 /usr/lib/firefox/firefox-bin
The first number suggests Firefox is taking nearly 1GB, but 512MB of that is just the X mapping my video card, I think. The second number shows it clearly taking around 450M.
--JoeWell, I do have over 30 tabs open across 5 windows, and I leave it open 24/7.
On my box it's currently taking around 450MB. I usually kill it when it gets to around 700MB. Maybe it's because I use GMail and Yahoo! Mail open all the time?