you're right...i always get that mixed up..the food calorie is 1000 regular calories....i usually stick with si (or atomic units for my molecular simulation), so i just remember 4.184J/g-degree-K
not to be nit picky, but you do have the right idea about heat flow...but specific heat is the wrong term...specific heat deals with the ability of something to hold heat, not transfer it...the actual definition of specific heat is in units of energy per degree of temperature...
example: water has a very high specific heat (1 calorie per degree (per kilogram)) that means that it takes a bunch of energy (1 calorie) to heat up a gram of water 1 degree. or conversely, you can store a lot of energy in water without raising the temperature....metals have a low specific heat, that it adding just a little bit of energy to a metal will raise the temperature a bunch.
what you were referring to is just the heat condictivity of lava, which when hardened on the outside is quite low.
you also have to remember that lava (once hardened on the outside) is a very poor conductor of heat. so even though the temperature may be quite high (compared to a conventional oven) the rate of heat flow may be quite low. incidentally that's why you can walk barefoot over hot coals...it just takes too long for the heat to flow from the coals to your foot.
we have one at our campus...it's kinda neat...the sun is about the size of a softball (maybe a little bigger) and the whole solar system goes out about 500 yards or so. so if you wanted a scale model to fit in a room, the planets would probably be too small to see.
the paralyzation of the http-input field that you speak of...on your computer does toggling numlock have any effect? i use mozilla ton tru-64 unix and i noticed random times where i couldn't type any text into mozilla. i finally was able to correlate it with numlock being on. i had a few other people with tru-64 verify that this happens to them, but no one on bugzilla was able to verify the same problem.
that's just a limitation in the language not supporting xor for non-integral types. but if you take the actual binary representaion for a float or double (like using a union) and do the xors you'll get the swap. you could even do the same thing for any data type you want as long as long as you can get to the bits to xor them (c++ classes will have more problems because of constructors)
actually i am a stinky gnu/linux hippie and i just decided not to get a bmw and buy an audi instead because i couldn't find the info i wanted on bmw's website because it won't render in galeon. after hearing your comment, i think i may write to bmw to let them know that.
the number i remember is 10^80 particles in the universe...so i think we'd need a bigger bar code than 20 digits. although i do agree with you. it makes more sence to just make the field bigger than we'll ever need. then some day we will actually need the room and it'll be there.
not to nit pick too much, but coal is more stable than diamond. if you leave a diamond sit for a couple of million years it'll turn back into coal. it's just that the time scale of diamond turning to coal is very long. but thermodynamically speaking, coal is more stable than diamond.
earlier this summer i tried to order a latitude without any operating system and everyone at dell said that i couldn't do that. so i decided not to get a new computer. is the announcement located on dell's webpage so that i can tell the operator if they're stopping 'no os' options by september 1, then there must be a 'no os' option now.
actually the voltage does have an effect on the velocity of the electrons.
the velocity of an electron in a metal is
q T v = ----- E
m
where q is the charge on the electron
T is the mean free time between collisions of the electron with a metal atom
m is the mas sof the electron
E is the applied electric field
the electric field is directly proportional to the voltage, thus the electrons do move at a speed proportional to the voltage.
this is true, but the problem is that to make chip run cooler you need to lower the voltage. if you lower the voltage you don't have the electrons running from place to place fast enough and the computers slow down. there's a very interesting book "the feynman lectures on computing" or something like that which is a series of lectures that richard feynman gave in the 70s i believe. he talked about this issues way before it became important. one of his proposals was to have massivly parallel chips running at very low voltages. at the voltages he was talking about it was statistically possible for the electrons to wander the wrong way so you need gates that are reversible. for example, the and gate is not reversible, you have two inputs and one output. if i tell you the output of an and gate, it's impossible for you to tell me the input. but there's another type of and gate called the CAND (controlled and gate) that has three inputs and three outputs, this one is reversible, so you can have electrons run backwards. anyway, i've rambled enough, so to get back to your post. we can't make chips cooler without lowering the voltage, but that'll slow down the electrons and everything else will slow down. there is a way around it, and i'm not sure why it hasn't been done yet.
i used quicken for about 5 or 6 years and then i decided to make everything linux, so i had to switch to gnucash. i think gnucash is more true to real accounting pricipals than quicken is (it uses the double entry method). all of my quicken data converted over seamlessly and worked great. for most things i like gnucash better, and i suggest if you're going to start, to start with gnucash, the double entry accounting works better if you start that way rather than converting after you get used to quicken's way of doing things. the only thing that i like quicken for better is some of the reports. different graphs and reports are easier to make with quicken, but it looks like gnucash is getting better there. another thing that gnucash lacks is automatic calculation of amortizations. when i had quicken all i had to do was click a button every month to update my mortgage, with gnucash i have to type it in each month. overall i suggest you go with gnucash. did i mention the open xml data format too?
actually they went from 32 boxes to 40 boxes. but i'm sure the hardware was years newer. there's no way an os change will speed something up by two orders of magnitude.
i don't know if there's a mac port, but zzt is one of the greatest classic games. plus if you get bored you can design your own levels. it's an old dos game made by epic, i don't know if mac has a dos emulator, but if so, then i suggest zzt.
speaking of individually listing congressmen who are for/against these things. is there any easy way to get voting records for what they actually did in previous congressional votes? i'd like to know what my representatives voted for last term before i go to the polls.
Re:Why is this on slashdot?
on
Qt vs MFC
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· Score: 1
yes, this is true. but i believe the parent poster said something about "understanding" the gui code. i used to be a programmer for ms apps and it took me about a month to get a handle on all the things that were going on in the mfc. unfortunately i have not done any qt programming, but i don't think it could be any harder to get started with than the mfc. even after i became an "expert" with the mfc, i still didn't write very clean code. there's just something about the mfc (maybe all the macros and no templates) that makes it hard to write nice code.
www.codeguru.com - actually i don't know how good it is anymore. but about five years ago when i worked as a windows application developer i found alot of help there
yes, you are absolutely right about 0.5 being exact in IEEE. i was thinking 0.1 when i wrote that. 0.1 cannot be stored exactly in IEEE. it gets stored as 0.9999999999999....
yes, i know i excluded things like the sign bit and the assumed 1 in the mantissa. i didn't need that to explain the difference between ieee and the calculator notation
and there is a difference between packed and unpacked decimal notation.
to represent decimal values 0-9 you need 4 bits, but 4 bits will get you 0-15, so you're wasting extra space. in the packed notaion you use something like 3.2 or so bits per digit. you have some bits spanning digits.
the TI-85 and TI-92 use a different method mantissa: 12 decimal digits wide base: 10 exponent: 3 decimal digits wide
remember that each decimal digit take 4 bits (unless they used packed decimal digits which i won't talk about), so the mantissa is 48 bits wide.
if the numbers are stored this way, then values like 0.5 can be stored exactly, where as in IEEE 754 they cannot. on a calculator, you want 0.5 to be exactly 0.5. i guess you want that too on a computer, but you give it up for the super duper increase in speed by not having to sore each digit with 4 bits and do all the extra work needed to do math on these numbers.
i can't seem to find the source i had that explained this. but i did read somewhere a while ago that calculators don't use the IEEE 754 standard for storing floating points, they go about it a different way, thus keeping more precision at the cost of speed. it may actually be a decimal type storage where each digit is represented by a few (4 ish) bits. this way there's not loss of precision at all. i'll try to find the info i had and get back to you.
Slashdot Mirror
you're right...i always get that mixed up..the food calorie is 1000 regular calories....i usually stick with si (or atomic units for my molecular simulation), so i just remember 4.184J/g-degree-K
example: water has a very high specific heat (1 calorie per degree (per kilogram)) that means that it takes a bunch of energy (1 calorie) to heat up a gram of water 1 degree. or conversely, you can store a lot of energy in water without raising the temperature....metals have a low specific heat, that it adding just a little bit of energy to a metal will raise the temperature a bunch.
what you were referring to is just the heat condictivity of lava, which when hardened on the outside is quite low.
you also have to remember that lava (once hardened on the outside) is a very poor conductor of heat. so even though the temperature may be quite high (compared to a conventional oven) the rate of heat flow may be quite low. incidentally that's why you can walk barefoot over hot coals...it just takes too long for the heat to flow from the coals to your foot.
we have one at our campus...it's kinda neat...the sun is about the size of a softball (maybe a little bigger) and the whole solar system goes out about 500 yards or so. so if you wanted a scale model to fit in a room, the planets would probably be too small to see.
the paralyzation of the http-input field that you speak of...on your computer does toggling numlock have any effect? i use mozilla ton tru-64 unix and i noticed random times where i couldn't type any text into mozilla. i finally was able to correlate it with numlock being on. i had a few other people with tru-64 verify that this happens to them, but no one on bugzilla was able to verify the same problem.
that's just a limitation in the language not supporting xor for non-integral types. but if you take the actual binary representaion for a float or double (like using a union) and do the xors you'll get the swap. you could even do the same thing for any data type you want as long as long as you can get to the bits to xor them (c++ classes will have more problems because of constructors)
mix this with openmosix and you have a real winner. i'm in the middle of doing this at home and so far it's working out great!
Lies, Damn Lies, Statistics, Studies, and Benchmarks
actually i am a stinky gnu/linux hippie and i just decided not to get a bmw and buy an audi instead because i couldn't find the info i wanted on bmw's website because it won't render in galeon. after hearing your comment, i think i may write to bmw to let them know that.
the number i remember is 10^80 particles in the universe...so i think we'd need a bigger bar code than 20 digits. although i do agree with you. it makes more sence to just make the field bigger than we'll ever need. then some day we will actually need the room and it'll be there.
not to nit pick too much, but coal is more stable than diamond. if you leave a diamond sit for a couple of million years it'll turn back into coal. it's just that the time scale of diamond turning to coal is very long. but thermodynamically speaking, coal is more stable than diamond.
earlier this summer i tried to order a latitude without any operating system and everyone at dell said that i couldn't do that. so i decided not to get a new computer. is the announcement located on dell's webpage so that i can tell the operator if they're stopping 'no os' options by september 1, then there must be a 'no os' option now.
actually the voltage does have an effect on the velocity of the electrons.
the velocity of an electron in a metal is
q T
v = ----- E
m
where q is the charge on the electron
T is the mean free time between collisions of the electron with a metal atom
m is the mas sof the electron
E is the applied electric field
the electric field is directly proportional to the voltage, thus the electrons do move at a speed proportional to the voltage.
a quick google search turned up this phd thesis:
http://www.cise.ufl.edu/~mpf/manuscript/
that describes some of these limitations.
this is true, but the problem is that to make chip run cooler you need to lower the voltage. if you lower the voltage you don't have the electrons running from place to place fast enough and the computers slow down. there's a very interesting book "the feynman lectures on computing" or something like that which is a series of lectures that richard feynman gave in the 70s i believe. he talked about this issues way before it became important. one of his proposals was to have massivly parallel chips running at very low voltages. at the voltages he was talking about it was statistically possible for the electrons to wander the wrong way so you need gates that are reversible. for example, the and gate is not reversible, you have two inputs and one output. if i tell you the output of an and gate, it's impossible for you to tell me the input. but there's another type of and gate called the CAND (controlled and gate) that has three inputs and three outputs, this one is reversible, so you can have electrons run backwards. anyway, i've rambled enough, so to get back to your post. we can't make chips cooler without lowering the voltage, but that'll slow down the electrons and everything else will slow down. there is a way around it, and i'm not sure why it hasn't been done yet.
i used quicken for about 5 or 6 years and then i decided to make everything linux, so i had to switch to gnucash. i think gnucash is more true to real accounting pricipals than quicken is (it uses the double entry method). all of my quicken data converted over seamlessly and worked great. for most things i like gnucash better, and i suggest if you're going to start, to start with gnucash, the double entry accounting works better if you start that way rather than converting after you get used to quicken's way of doing things. the only thing that i like quicken for better is some of the reports. different graphs and reports are easier to make with quicken, but it looks like gnucash is getting better there. another thing that gnucash lacks is automatic calculation of amortizations. when i had quicken all i had to do was click a button every month to update my mortgage, with gnucash i have to type it in each month. overall i suggest you go with gnucash. did i mention the open xml data format too?
actually they went from 32 boxes to 40 boxes. but i'm sure the hardware was years newer. there's no way an os change will speed something up by two orders of magnitude.
i don't know if there's a mac port, but zzt is one of the greatest classic games. plus if you get bored you can design your own levels. it's an old dos game made by epic, i don't know if mac has a dos emulator, but if so, then i suggest zzt.
speaking of individually listing congressmen who are for/against these things. is there any easy way to get voting records for what they actually did in previous congressional votes? i'd like to know what my representatives voted for last term before i go to the polls.
yes, this is true. but i believe the parent poster said something about "understanding" the gui code. i used to be a programmer for ms apps and it took me about a month to get a handle on all the things that were going on in the mfc. unfortunately i have not done any qt programming, but i don't think it could be any harder to get started with than the mfc. even after i became an "expert" with the mfc, i still didn't write very clean code. there's just something about the mfc (maybe all the macros and no templates) that makes it hard to write nice code.
heh, i remember that. i also wrote a program to do that. brings back memories of screwing off in college.
www.codeguru.com - actually i don't know how good it is anymore. but about five years ago when i worked as a windows application developer i found alot of help there
i can't seem to find the source i had that explained this. but i did read somewhere a while ago that calculators don't use the IEEE 754 standard for storing floating points, they go about it a different way, thus keeping more precision at the cost of speed. it may actually be a decimal type storage where each digit is represented by a few (4 ish) bits. this way there's not loss of precision at all. i'll try to find the info i had and get back to you.