Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment: Re:Doing it wrong. (Score 1) 116

by abies (#49742581) Attached to: Hydrogen-Powered Drone Can Fly For 4 Hours at a Time

It is very hard for me to get exact numbers in few minutes, but we would need to compare amount of people transported by dirigibles/number of deaths to amount of people transported by planes/number of deaths. I have no doubts that more people died in airplane crashes over all time, but at same time I feel that number of people who survived plane flights will anyway make this ratio better by orders of magnitude.

Big part of it might be due to maturity of technology - if we had dirigibles now, they would be quite flawless. But I don't think that you can compare 1900-1940 era of dirigibles to 1950+ era of commercial aviaton in any kind of safety metrics and have dirigibles come on top.

Comment: Best deals? (Score 3, Insightful) 72

by abies (#49591985) Attached to: How an Open Standard API Could Revolutionize Banking

I can understand benefits of standard, open API for automatic processing of orders for companies and various home-budget tools. But I don't get "automatically calculating the best deals in complete transparency". Do you really need a program, querying 100 of banks in realtime for the best place to have your current account _today_? And tomorrow you are going to switch, because international transfers over there are half cent cheaper?
API for transactions - sure yes. But API for bank offers metadata? Isn't it bit too much?

Comment: Re:uh... (Score 3, Interesting) 170

by abies (#49574959) Attached to: Verizon Tells Customer He Needs 75Mbps For Smoother Netflix Video

I understand your idea, but I think this is not true with TCP/IP. Latency IS affecting throughput considerably.
a) There is a limit of un-acked bytes which can be pushed, so there is guaranteed limit depending on distance (and with 5 seconds it is going to be very visible)
b) With any kind of packet loss, which is to be expected, window size will reset, slowing it even more

Only info I was able to find about that was quite old and metioning various workarounds which will be implemented for that in 2010 or so ;) Does anybody know how it looks like these days on majority of internet? What will be expected maximum throughput over TCP/IP with 5s ping, with 0% packet loss, 0.1% packet loss and 1% packet loss?

Comment: Re:No disrespect to GCC, but why not LLVM? (Score 1) 78

by abies (#49535401) Attached to: GCC 5.1 Released

I know - this is why it was taking me 2-3 days to find a 100% reproducible bug (at least before I added debug printfs...). I just could not believe the gcc might be at fault.
Now, to be completely honest, first bug was present only on SPARC cpu on Solaris, x64 AMD was fine. We had to use gcc because one of libraries we were using was based on stlport compiled with gcc, so CC was out of question. I suppose that SPARC backend of gcc get a lot less testing. But second one on vanilla x64 intel linux and is still happening (gcc 4.8.2, but I think it was also checked to happen with 4.8.3). Magic option to avoid bug is -fno-tree-dse, whatever this means.

But yes, I was just unlucky - I have no doubts that gcc works fine for thousands programs out there. Guess what - it also works fine for both programs I have done, AFTER finding magic reordering of lines or command line option to get them to work. Who knows how many strange options are lurking in some of popular programs to work around similar issues ;)

Comment: Re:No disrespect to GCC, but why not LLVM? (Score 3, Interesting) 78

by abies (#49534923) Attached to: GCC 5.1 Released

GCC is the old, very reliable and well-known workhorse, that produces good results.

I'm mostly working with java and python, but I had two non-trivial encounters with gcc in past 10 years. In both cases C++ code was written by experts with me being just slightly involved.

In both cases I have hit gcc bugs which resulted in very wrong behaviour. Both times I have spent 2-3 days trying to find any reasonable explanations, ended up doing assembly dump of generated code and finding a place where gcc was generating plain wrong opcodes. In one case it was shift +or of two 32-bits to make a 64-bit number which sometimes was not loading one of registers from the stack, in second case conditional jump where condition was not set properly on second and further loops. Best part of first one was that it was working as long as there was any printf in same function (even 20 lines further down the method) - but as soon as we commented our debugging printf it was back to crashing.

Solution to first problem was to reorganize method randomly till it started compiling properly with same random useless local variables. Solution to second was to do some kind of -no-whatever flag, which we have found of by bisection by recompiling over and over with all the combinations of flags.

In both cases 'experts' were saying - no chance gcc can make such basic mistakes, you are looking in wrong place, I don't want to look at assembly dump, you are not supposed to second guess the compiler, linux kernel is using gcc so it is good, etc etc.

Yes, I probably just have bad luck. But I just don't accept 'reliable and good results', being burned 2 out of 2 attempts to use gcc in commercial work.

Comment: Re:4x strategy when? (Score 1) 58

by abies (#49509553) Attached to: Computer Beats Humans At Arimaa

I don't think it is THAT complicated. You don't really have hundreds of options each time - you have probably 10-20 options or so like 'explore', 'invest in infrastructure', 'build up military', 'attack players', etc. For each of these goals, you might need to do number of small actions - but I don't think this part is hard for computers. Given goal of 'churn out best miliary units in 5 turns', computer should be always able to come up with optimal set of moves.
Now, moving between these higher level goals is certainly non trivial. But these are longer term decisions (few turns probably), so I don't think that decision tree explodes that much - if you keep micromanagement and high level goals separate.
With chess, separating overarching goals from low level movements is a lot harder, as every move influences a lot more aspects of play and a lot of choices are effectively forced on both sides when you go down certain path. When you want to improve your city by building farms with no enemy units in close range, it really doesn't matter which of grasslands you go to first. I'm quite sure that most players play these things on 'auto' anyway.

I'm not trying to say that AI in cmputer games is easy. I'm just saying that trivially multiplying all possible choice of inputs by length of game and comparing that number to chess is not really fair.

Comment: Re:They're called trees. (Score 4, Informative) 128

by abies (#49493749) Attached to: Breakthrough In Artificial Photosynthesis Captures CO2 In Acetate

Europe and Asia (where the former has few forests left [...]
Canada and the United States 26%
European Union 35%

And from
Europe it was 36.5% in 200 and 37.9% in 2012.

Not sure how good these statistics are, because it says 'Canada &United States = 26%' and then 'Canada =31%' and 'USA= 30.84%'... In any case, Europe has more forest area atm and amount of forest is growing rather than decreasing.

Or did you mean Europe has few forests left compared to situation from 2000 years ago? I can agree with that, but I don't think that global warming is THAT old - we used to have some mini ice age in meantime I think...

Comment: 4 types of immortality (Score 0) 313

One of the TED talks was covering this subject - it was really a kind of eye opener for me
Presenter argues that there are 4 basic stories about immortality, which get repeated across the ages, with slightly different color, but same underlying idea - and realizing that helps to put some distance into believing latest 'science magic'
1) Elixir - immortality of the body (Philospher Stone, Fountain of Youth, hormone teraphy, gene telomere therapy etc)
2) Ressurection - getting raised from dead (bible Apocalypse raise-from-dead at end of times if you are buried properly, being ressurected from cryogenic sleep by future scientists if frozen properly)
3) Soul - preserving mind/person even if body is gone (most religions afterlife/reincarnation, mind upload)
4) Legacy - preserving your ideas and/or genetics (having children, rising/teaching children, creating works of art, science discoveries, blowing yourself up to good of your village/country/religion etc)

In this case, parents just wanted to believe their 'scientific' version of ressurection fairy story. It is just more expensive and slightly more gruesome than lot more common rite of putting body into ground with priest chanting over it, so it can get ressurected by allmighty God at end of time. As long as child was properly circumcised in time. Or baptized. Or hasn't killed any puppy. Or was frozen to exactly proper temperature with right mix of chemicals.

The last person that quit or was fired will be held responsible for everything that goes wrong -- until the next person quits or is fired.