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March 9

backtick in Python

Looking over some Python code of mine, last edited in 2004, I see here and there the syntax `x` — which I haven't used recently, and which isn't mentioned in my most current Python reference. An old reference implies that it might be equivalent to repr(x), but does not explicitly compare them; they're not mentioned close together. Is there a difference? Is `x` now deprecated? —Tamfang (talk) 08:07, 9 March 2014 (UTC)[reply]

Backticks cause the reference compiler to emit a UNARY_CONVERT bytecode, which does what repr() does but without an (explicit) function call. This is discussed at this StackOverflow question. Python3 removes the UNARY_COVERT bytecode and the backtick syntax becomes invalid. -- Finlay McWalterჷTalk 10:13, 9 March 2014 (UTC)[reply]

The actual patch to remove UNARY_CONVERT from Python3 is here; it shows the old C code in ceval.c, which was largely an invocation of PyObject_Repr() -- Finlay McWalterჷTalk 10:23, 9 March 2014 (UTC)[reply]

Using uTorrent..!

Is using uTorrent to download films, softwares etc... is illegal?--Joseph 17:32, 9 March 2014 (UTC)[reply]

Depends on where you are and what you download - anything beyond that would be legal advice, something we can't give here. WegianWarrior (talk) 17:43, 9 March 2014 (UTC)[reply]

Just to clarify uTorrent is a program which implements the Bittorrent protocol. Bittorrent is used to download large files, whether they are movies, software installation discs, etc. It doesn't matter which bittorrent program you use, or even if you download the file by a different mechanism. What DOES matter is (a) is the file is in copyright, and (b), if so, do the copyright holders agree with it being distributed. However, as WegianWarrior said, we can't answer that bit. CS Miller (talk) 19:27, 9 March 2014 (UTC)[reply]

So, from where I could seek more on this?--Joseph 04:57, 10 March 2014 (UTC)[reply]

I'm not sure what you're looking for. You could read Legal issues with BitTorrent. As previous replies said, what you're downloading matters much more than whether you used uTorrent to download it. -- BenRG (talk) 05:44, 10 March 2014 (UTC)[reply]

Just spotted a recent article 30 Sites For Legal (and Free) Torrents. It includes lots of software, independent films, books and music plus archived material.--Salix alba (talk): 07:23, 10 March 2014 (UTC)[reply]

Remote desktop

I want to admit I am not sure I will use this information but given the breath of people's knowledge around here any contribution might help me to make the final decision. In short I need to demonstrate graphics of functions one of my programs generates to a person with whom I am planning to work on a serious project. I know I can use remote desktop provided by Windows 7 but I believe (perhaps wrongly) that I will need a static IP address for that. I work with remote desktop at work and am planning to ask our computer people how they run it. I have an impression that they simply purchased or rented a software from a company. The system works like this. In one incarnation I generate a six digit code before I get a phone call. I then give this remote recipient this code and we establish what essentially is a two way web cam connection, sort of a local Skype. This is not what I want. I can use Skype for that. I am not sure with the Skype the image resolution will be good enough.

The other variant is when something breaks down in my machine, software wise. I call a number, alert a person, then click a few tabs here and there and he takes over my mouse cursor. I don't see him. I want a system like this because I am planning to do it rather a few times.

I guess my question is: Are there safe, proven systems like this around that I can download and use and then uninstall?

Thanks, --AboutFace 22 (talk) 19:11, 9 March 2014 (UTC)[reply]

It shouldn't matter if the machine you are remoting from is on a dynamic IP or not. Nor should it matter if the target machine is on a dynamic IP address. However, you need to know what the target machine's IP address is; you could take a note of the firewall's address before you leave. You might need to enable TCP port forwarding in the firewall for it to work. To avoid any embarrassment, I strongly recommend you test it from a web-cafe first. Out of interest, can't you run the program on a laptop you can take the client's site? CS Miller (talk) 19:33, 9 March 2014 (UTC)[reply]

Thank your for the information. Very helpful. I just gifted my windows 8 laptop to my daughter but if worst comes to worst I can get another one. But it is an interesting thought. Well, actually the man I will be working with should know much about it. So, in your opinion the remote desktop is the way to go. Very interesting. Thanks, --AboutFace 22 (talk) 20:46, 9 March 2014 (UTC)[reply]

I use the free version of ScreenLeap. -- Gadget850^talk 21:14, 9 March 2014 (UTC)[reply]

Role of BitCoin exchanges

I was under the impression that a BitCoin exchange allows users to purchase BitCoins with a national currency, and to redeem BitCoins back into a national currency, possibly by matching buyers and sellers. Once a BitCoins is bought, the exchange isn't necessery any more. However, the recent failure of Mt.Gox seems to have invalidated/lost several thousand BitCoins, I'm not so sure anymore. Can anyone tell me if I was correct? CS Miller (talk) 19:38, 9 March 2014 (UTC)[reply]

My understanding is that you are correct, and I share a bit of your confusion, so I will keep an eye on future responses. Best I can figure is that people were using Mt. Gox like a bank, even though they didn't really need to. One possibility is that a majority of the total value held by Mt. Gox was in a large number of small accounts, which were being used for just-in-time liquidity. In which case, nobody was using it "incorrectly", it's just a lot of small amounts that add up quickly. SemanticMantis (talk) 21:29, 9 March 2014 (UTC)[reply]

It's easy to believe that many people left a lot of money in there, especially people who bought bitcoin long ago planning to sell it when it appreciated in value, and who may have no clue how to install bitcoin software and manage their own wallet. This guy claims to have had £70,000, 500,000 baht, and 450 BTC in his account, and he's a "leading British Bitcoin dev" who ought to know better.

The missing amount, which is allegedly around 850000 BTC (!), was apparently lost piecemeal over a period of years. I think it's possible that it really was lost in the sense that the private keys are gone so it can never be spent. Mt Gox did destroy about 2600 BTC with a programming error in 2011 ([1]). I suppose it's also possible that the keys are buried in the ruins of Mt Gox somewhere, but no one seems to expect that. It seems most likely that it was stolen, i.e., transferred to addresses whose private keys are known only to the thieves. -- BenRG (talk) 02:12, 10 March 2014 (UTC)[reply]

Mt. Gox did not only lose bitcoin. It also lost real money - U.S. dollars, euros, and so on. (Forgive my snarkiness, but as far as I'm concerned, the bitcoin loss just isn't real money). Mt. Gox also lost lots of real money: after any individual deposited U.S. dollars (in exchange for bitcoins), Mt. Gox would use that depositor's money to make purchases; to settle credit owed to investors; to buy bitcoins from other people, and so on. They say as much in their hastily-written, "accidentally-leaked" memo! After all those transactions, Mt. Gox is still out a few hundred million dollars: lost by poor accounting practice. They are presently writing this all off as part and parcel to the "bitcoin theft," and truthfully it will be hard to disentangle the two (because, as an exchange, money and bitcoin were commonly exchanged). Mt. Gox adamantly denies the reality that it was operating as a fractional reserve bank and that it could not sustain its first major bank run. They flatly deny this behavior in their memo, all while asking for infusions of more capital to refresh their reserve.

At the end of the day, bitcoin had value because it could easily be traded into U.S. dollar. This is not what bitcoin enthusiasts claim about bitcoin; enthusiasts claim that the currency has value because an anonymous crowd will trade goods and services for it. Yet, without an exchange to convert into and out of U.S. dollars (and Euros, and other currency), bitcoin has no value. In much the same way that my local supermarket will not accept Canadian dollars, it will not accept bitcoins, so the "face value" of the currency is totally meaningless unless you can find somebody who will exchange it for real currency. The difference is, I can easily find dozens of reliable institutions that will convert Canadian dollars into my local currency. Reliable institutions believe that Canadian money has value (even if it is not currency here) because Canada has all the hallmarks of a proper, functioning, regulated, real fiscal system.

Shutting down the dollars-to-bitcoins exchange - at least, the biggest one - has essentially isolated the "economy of bitcoins" from the rest of the world economy. Presently, bitcoin economies aren't self-sustaining (unlike, say Canada - whose currency has value because all parts of an entire economy of a sovereign nation trade in that currency). Bitcoin economies still require these exchanges in order to remain in touch with other economies that provide necessary goods and services that aren't yet available for purchase in bitcoin - like local groceries, or large supplies of skilled labor. I expect the bitcoin "economy" will suffer the same effects that a small nation sees when it is sanctioned or embargoed - totally isolated from outside economies. The "value" of the currency will wildly swing between bouts of hyperinflation and total value-collapse; market liquidity will fail; goods and services will not be available for purchase at any bitcoin price, no matter how high or low. But you don't have to take my word for it... you can try to buy some goods and services using bitcoin now! In the absence of an exchange, the currency isn't useful. Nimur (talk) 03:18, 10 March 2014 (UTC)[reply]

Mt Gox hasn't been the largest bitcoin exchange for some time. I don't think its demise has made it significantly harder to buy or sell bitcoin. The price at other exchanges took a hit but doesn't appear to be in a death spiral.

I think whether bitcoin is money is a meaningless matter of definition. I classified it as money above simply because I didn't feel like writing "money or bitcoin" over and over. -- BenRG (talk) 05:19, 10 March 2014 (UTC)[reply]

It's also not true that exchanging between bitcoin and real money isn't possible without an institution like Mt. Gox. If I believe that bitcoin is valuable, and you have bitcoin, I can pay you US dollars in exchange for your bitcoin. There's nothing difficult or unusual about that exchange, except for the possibility of fraud. --Bowlhover (talk) 06:36, 11 March 2014 (UTC)[reply]

Generally, the exchange will charge a fee to withdraw bitcoins/fiat currency, and will associate an amount of each with your account. This reduces the administrative overhead of the exchange, since a customer can make thousands of trades, with the exchange only needing to update their internal databases, and not actually send any money or coins externally until the customer withdraws their funds. It also makes things easier for the customer, as traders wishing to make a number of fast trades don't need to wait for funds to transfer, or bitcoin transactions to confirm before making a second trade. Unfortunately, it also leads to people effectively using the exchange as a bank, which means that they can lose everything if the exchange goes down. MChesterMC (talk) 12:53, 11 March 2014 (UTC)[reply]

What's the world record for computer chess moves per second?

Is it still Deep Blue? I think they only used consumer desktop hardware after that, or at most workstation, but come on, consumer hardware has had 17 years of Moore's Law. They always say that newer chess engines know what to not bother calculating and what to calculate deep and they do more than count material points but how many MPS is the hardware capable of if they still did it the old way? How many MPS brute force would be needed to equal the playing strength of today's pruning engines? Sagittarian Milky Way (talk) 21:20, 9 March 2014 (UTC)[reply]

The article on computer chess seems to indirectly address some of your questions. I'm no expert on computer chess but know that today's chess engines focus more on efficient pruning of search trees rather than relying on brute force the way Deep Blue did. It's very difficult to equate MPS to playing strength because it depends on the algorithms used by the engine (somewhere in the article they compare Pocket Fritz's 20,000 MPS to Deep Blue's 200 million MPS). You can also check the ELO rating of modern engines and use this as a basis to compare playing strength. If someone had the skill and budget to use the most efficient engine on the fastest supercomputer, it would be a monster player perhaps surpassing 4000 ELO but it still would not come close to solving chess. Sandman1142 (talk) 10:14, 11 March 2014 (UTC)[reply]

More Gmail contacts

On one side, I have a gmail account, with several contacts. On the other, I have an excel file with a database, including names and e-mails, and I was asked to upload those e-mails to the gmail account. I have tried exporting the contacts in CVS format, which generated an excel file with a single column, with all the fields at each entry set apart by commas. So, I arranged the other excel to display the names and e-mails in a similar format, copy the result to the cvs file, and import it back. I get error messages. So, which is the correct way to do this? Cambalachero (talk) 23:39, 9 March 2014 (UTC)[reply]

Here is Gmail's support document on the subject. Dismas|^(talk) 00:02, 10 March 2014 (UTC)[reply]