Wikipedia:Reference desk/Archives/Computing/2014 October 23

= October 23 =

AT&T behavior
AT&T recently added fiber optics in my area, and immediately dropped the speed to a crawl on their copper wire DSL system to "encourage" everyone to upgrade to fiber optics (their technician admitted this to me). Have they done the same thing elsewhere ? Have there been any protests ? StuRat (talk) 03:23, 23 October 2014 (UTC)
 * i think i recall some save the Internet protests regarding the control of speeds, so net neutrality may be a relative to what you're referring to? particularly "control of data" section of latter article  ~Helicopter   Llama~  12:17, 23 October 2014 (UTC)


 * AT&T's behavior is often painful to decipher...and I've long learned that in the absence of evidence, it's generally wiser to attribute failure to incompetence rather than malice.


 * 12 years ago, I had a copper DSL line from them which had worked solidly for many years.  One day I got a call out of the blue offering me a free upgrade to 2x speed.  Obviously, I leaped at the chance - they came and installed the new equipment as promised.   I soon noticed my network speed was now about 1% of what it used to be - and found that I was getting a 99% packet failure rate!   I called to ask for help and they said that I was too far from the telephone exchange to use the higher speed DSL.   I asked them to down-grade me to the 1x speed service I had before and they said that they had no mechanism in place to downgrade people's service.   Then they offered us their cellular service instead - which was outrageously expensive, slow as all hell - and only worked when the antenna was 30 feet from our house!   So in the end, they just cancelled my contract so I was left with no internet at all!   I complained to AT&T headquarters and they promised to refund the payments for the period when I had the 2x service - which was something like $15...gee...thanks!   Soon after, we moved away from the area - so it stopped being a problem. Then, just last year, a decade after all of that nonsense, I got a call from a collections agency saying that I owed them $1,000 because of an unpaid $15 bill from AT&T dating back a dozen years ago.   All efforts to get AT&T to admit the error fell on deaf ears ("we've turned the debt over to a collections agency and now it's not our problem") and I ended up settling that 'debt' for $150.   I swore off AT&T - but recently, they made us a VERY good offer for cable TV+Internet at low cost and with phenomenal Internet bandwidth.   When it was all plugged in and running, the internet bandwidth was terrible.   I complained that it fell far short of their promise and after several techs visited the house and (mostly) just rebooted the cable box and the WiFi moden, they told me that to get bandwidth higher than our old TimeWarner system, I'd have to turn off all of the TV's in my house...turns out that the stated numbers were for TOTAL bandwidth..minus TV.   With two or three TV's turned on, my internet ran like dialup!   So we told them in no uncertain terms to pull out their crappy system and pay for the re-installation fees from TimeWarner - which they EVENTUALLY agreed to do.   I'm expecting another call from a collections agency in about another decade - so the final statement and receipt of payment are in our wall-safe where I'll be able to find them again!


 * However, while it's possible that they did this to you maliciously - it's more plausible that they are phasing out the DSL equipment as the demand for it decreases - and there is some kind of bottleneck arising because of that.  The 'admissions' of a tech don't mean much...it might be true, it might not.


 * SteveBaker (talk) 16:27, 23 October 2014 (UTC)
 * Do you know if the sync speed has changed at all? Beyond what SteveBaker has said, if there's any connection at all between the fibre and the existing copper network (e.g. the same fibre is used from the DSLAM/cabinet) it's also possible someone screwed up and bumped a wire, connected something incorrectly or whatever when they were installing the fibre. Nil Einne (talk) 14:38, 24 October 2014 (UTC)

NonNetwork Printer Shared Between Computer
Yesterday I needed to move a printer (that lacks an ethernet jack and does have any type of networking) that was setup as follows: the usb runs from the printer into a box that has an ethernet cable coming out the other end, the ethernet cable runs into a switch, then that connects into two computers. The printer works from either computer and was installed without discs. I moved the printer, installed it using by plugging the usb into two different computers, then duplicated the setup with the wires - however, in this case, it does not work (I didn't expect it to...). What do I need to do to duplicate this setup? I'm usually fairly savvy with this type of thing, but I wasn't aware that a setup like that could work, any suggestions? Thank you for any help:-)Phoenixia1177 (talk) 09:20, 23 October 2014 (UTC)


 * The box was surely a little print server appliance. So, as far as each PC (which I assume you mean Windows machines) is concerned, the printer is a network printer. When you installed the printers with USB connections, you created what, to Windows, is logically a different, local printer. You need to have the Windows machines add a new printer, but have them search on the network for it. -- Finlay McWalterᚠTalk 10:43, 23 October 2014 (UTC)


 * I tried that, nothing is found for a network printer - the printers config page does not show an ip address, nor even have a line to list one. On the two printers it works on, the printers are not installed as network printers, though many fields under their properties are listed "unavailable", this changes if I plug it in directly via usb. The box, as far as I could see, looks like it is simply a converter, like this: .Phoenixia1177 (talk) 10:47, 23 October 2014 (UTC)
 * A print server doesn't need to be very complicated. Any smart phone with an ethernet port and USB host most could nominally function as a print server, and that has an unnecessary screen, battery and other stuff. That said, are you suggesting that the device doesn't have any external power? This is somewhat unusual. While some printers may provide power to special USB2Go or host ports (for connecting phones, cameras and may be smart cards and external discs), these are generally seperate from the main USB port used for connecting the printer to the computer. And even if they are the same, a printer wouldn't normally provide power when connecting as a client. And connecting to the printer in USB host mode wouldn't normally allow the device to connect via normal drivers etc. So if the device really has no external power (which to be clear, would include a microUSB connection to a computer) and I'm guessing it's not getting Power over Ethernet that would mean it's probably somewhat unusual. There's still a resonable chance it is a print server and the printer has some special USB mode which provides power but allows the server to still connect as normal but it's difficult to say without more info on the device. I'm pretty sure it's not the same as what you linked to.
 * Anyway, I'm slightly confused about the current setup. Is the printer going to the same switch as before? Did you move the switch? Or change the connection between the computers and the switch in any way? Are you using the same ethernet cables? Have you verified the ethernet connection between the computers is working? Did you save anything before moving so that we can perhaps work out how it was connecting before? If you can move it back, does it work when you do so?
 * BTW what version of Windows are you using? I seem to recall on some older versions of Windows, 'network printer' was confusing since it referred to those connectable via a few different network printer standards, but not via the Windows (File and) Printer sharing i.e. Server Message Block which a number of printer servers use (probably using SAMBA) for simplicity and compatibility. Have you tried browsing for the printer on the local network like you would browse for shared files?
 * Nil Einne (talk) 14:32, 24 October 2014 (UTC)
 * What is the brand and model of the box? Most external print servers have a software discovery tool. --  Gadget850talk 21:23, 24 October 2014 (UTC)


 * Thank you for the help and suggestions - I just ended up buying a new printer (it was easier, and the new one is a better one anyway); the prior set up had some goofiness going on, besides the mentioned, and it seems easier to just leave it be and redo it later if need be - it is, apparently, networked, but there is more stupidity that explains the other things mentioned; I'm not impressed by what the other person did, but don't feel the need to mess with it.Phoenixia1177 (talk) 15:13, 25 October 2014 (UTC)

Resource for Raytracer
Hi. Can anyone recommend a good resource to help me understand how to calculate a ray for a camera in a ray tracing program? For example, I have X and Y on a viewing screen, and I want to convert it to a ray with the origin at the aperture of my camera and passing through the appropriate pixel in the screen. I was looking at scratchapixel but I wonder if there is something else you can recommend. Thanks. Duomillia (talk) 17:53, 23 October 2014 (UTC)

Why would you need another resource than scratchapixel? To our knowledge it explains these things very well? — Preceding unsigned comment added by 78.149.116.147 (talk) 09:08, 26 October 2014 (UTC)


 * You need to know how far the virtual screen is from the camera - which would provide the Z coordinate for each pixel. The distance may be specified directly, but more commonly you need to know the horizontal and vertical field of view.   So, typically, you might use a 60 degree horizontal FOV.  If the virtual screen is considered to be (say) 1 meter wide - then it's going to be (0.5/tan(30 degrees)) meters from the camera.   The actual screen pixels will be spaced equally across your 1 meter wide virtual screen - so you need to know the screen's origin and X and Y resolutions to be able to compute an (x,y,z) for each pixel.   Once you have that, it's easy to figure out a vector describing the ray from the camera through each pixel. SteveBaker (talk) 19:31, 23 October 2014 (UTC)


 * Have you reviewed our list of ray tracing software? A lot of free software exists to do what you want, with varying complexity.  Commercial packages are also available.  Nimur (talk) 21:11, 23 October 2014 (UTC)