Wikipedia:Reference desk/Archives/Computing/2011 March 17#Calculating Powers of 2 in Octave

  I'm new to Octave, and I'm trying to calculate powers of two from 1 to 50. I tried using the following code

n=1:50; m=2^n; disp(m)

but I keep getting the error message error: for x^A, A must be square. What am I doing incorrectly, and how do I fix it? Thanks. Rocketshiporion♫ 01:43, 17 March 2011 (UTC)

:Well, since exponentiation doesn't require A to be square ^ must mean something different. However, the manual tells ^ means exponentiation, so no clue from there. 212.68.15.66 (talk) 06:26, 17 March 2011 (UTC)

::Try the .^ notation, which performs element-wise exponentiation. Octave uses vector syntax to make element-wise operations explicitly different than vector-operations. More information on this at [http://www.gnu.org/software/octave/doc/interpreter/Arithmetic-Ops.html#Arithmetic-Ops the Octave Manual - Arithmetic Operations section] or [http://www.chemie.fu-berlin.de/chemnet/use/info/octave/octave_4.html#IDX125 this Octave Info Page on operators syntax], from Freie Universität Berlin. Nimur (talk) 07:01, 17 March 2011 (UTC)

:Thanks - the .^ notation worked, but now it outputs the fifty numbers in the format from 2.0000e+000 to 2.8147e+014. How do I get it to display the numbers in full? Thanks again. Rocketshiporion♫ 08:54, 17 March 2011 (UTC)

::I figured it out myself - I have to use format long. Rocketshiporion♫ 09:15, 17 March 2011 (UTC)

Suppose I want to send someone a link to a music video on YouTube, but I don't want them to able to know the artist as they're listening to it, I want to them to remain in the dark about who they're listening to until I tell them who it is, is there any possible way I can achieve that? 24.189.87.160 (talk) 05:40, 17 March 2011 (UTC)

:If you're a crafty person, I think it's possible to create a YouTube client that hides away this information - however, you'd have to make your friend use that or it wouldn't help at all. 212.68.15.66 (talk) 06:21, 17 March 2011 (UTC)

::Or instead of sending them a link you could record the music as an mp3 file and send that to them.--Shantavira|^{feed me} 09:21, 17 March 2011 (UTC)

::: It's kinda hacky, but using [http://tubedubber.com/ Tubedubber] to swap out the video but not the audio should work. Paul (Stansifer) 14:25, 17 March 2011 (UTC)

::::You'd still need to hide the YouTube interface potentially wouldn't you? Since doesn't YouTube often identify music automatically so they can tell you where to buy the song, know who to pay royalties to and stop you listening if you live in places where they lack royalty agreements? I have to agree with Shantavira here, is there any particular reason it has to be YouTube? Nil Einne (talk) 21:56, 17 March 2011 (UTC)

:::Yes, the person I'm sending it to is someone I know ONLY through YouTube, and I'm not about to share my email address with a complete stranger. 24.189.87.160 (talk) 05:00, 20 March 2011 (UTC)

:Here's a possible solution. Go to the YouTube video you want, look at the address and find the 11-character code after v=. This is the video id. In the text below, replace VIDEOID with the video id, then ask your friend to paste this into their browser's address box.

::javascript:void(function(){d=document.open();d.write('');d.close();}())

:This will draw an small iframe that embeds the video but just shows the playback controls. Only a very tiny version of the video appears behind the middle of the red position bar. Be aware some videos don't allow embedding, so it won't work in that case. --Bavi H (talk) 01:32, 18 March 2011 (UTC)

: Thanks,,) I'll try it out. 24.189.87.160 (talk) 05:00, 20 March 2011 (UTC)

::See [http://code.google.com/apis/youtube/player_parameters.html YouTube Embedded Player Parameters] for other parameters you can use in the embed link. --Bavi H (talk) 01:39, 18 March 2011 (UTC)

A webpage has some audio being streamed using Flash 10. How can I record this on my Win XP computer please? I'm using Firefox but also have IE installed.

Supplementary question: I don't suppose there is any alternative to Flash 10 to play streaming video? Thanks 92.24.180.239 (talk) 14:10, 17 March 2011 (UTC)

:Answer to your supplementary question: It depends on the website from which you're streaming the video. [http://www.youtube.com/html5 Here's the page on YouTube] where you can enable HTML5 video instead of Flash video. Supporting formats other than Flash is spreading because of the refusal of Apple to include Flash support in their iOS products. PS: If you're just asking whether Flash video on a website can be viewed on your computer with software other than Adobe Flash, see the "FLV players" section of our Flash video article. Comet Tuttle (talk) 16:43, 17 March 2011 (UTC)

:http://www.downloadhelper.net/ http://jdownloader.org/ http://www.applian.com/download-videos/ ¦ Reisio (talk) 18:36, 17 March 2011 (UTC)

The point about Flash 10 is that the stream will not allow you to save it, as it is encrypted in some way. So the first link supplied by Reisio will not work, the second link is nothing to do with audio or video, and for the final one I believe the free trial only allows you to record the first five minutes and it probably wont work anyway.

Is there any way of saving the audio rather than the stream directly please? Thanks 2.97.215.199 (talk) 19:48, 17 March 2011 (UTC)

:Not an answer, but a pointer for other editors: 2.97 is referring to a claimed method of copy protection that is mentioned on [http://www.adobe.com/products/flashplayer/features/ this page] under the header "Content Protection". PS: [http://www.adobe.com/products/flashmediaserver/pdfs/flashaccess_wp_protectstreaming.pdf Here is an Adobe white paper] on this form of DRM. It made my eyes glaze over. Comet Tuttle (talk) 20:31, 17 March 2011 (UTC)

: XP should allow you to record, on a wave editor, whatever sound is being output by your computer. More modern versions of Windows probably won't allow this, since Vista introduced the design decision that enforcing copy protection is more important than allowing the user to achieve things. See for instance the FAQ for Goldwave: [http://www.goldwave.com/faq.php] "How do I record Internet audio or the speaker output?" 213.122.0.29 (talk) 21:57, 17 March 2011 (UTC)

::I've not had any problems recording the system stereo mix on Windows 7 using Audacity 82.43.92.41 (talk) 01:12, 18 March 2011 (UTC)

:For systems that don't support "stereo mix", programs such as Total Recorder [http://www.totalrecorder.com] exist, however that particular one is not freeware.

{{resolved}}

How are windows and applications handled on Macs? Looking at screenshots such as this, I can't seem to find any place were windows are handled, other than on the dock. --T H F S W (T · C · E) 17:28, 17 March 2011 (UTC)

:Exposé (Mac OS X) is what most people use to navigate windows. With a certain trackpad gesture or key press, all of the currently open windows are tiled in front of you. You can also use the Dock to open a mini-Exposé consisting of all the open windows for a given application. A slightly less frequently used system is Spaces (software), which lets you create multiple desktops in addition. 108.18.208.188 (talk) 17:48, 17 March 2011 (UTC)

::Mac OS X uses Quartz Compositor and Core Graphics to "handle" windows. (These are the Apple software that are comparable to an "X server"). Exposé is the most common user-interface to the windowing kit. Any application that wants to deal with windows or widgets will use the Quartz and Core Graphics APIs. Here's the high-level overview, [http://developer.apple.com/library/mac/#documentation/MacOSX/Conceptual/OSX_Technology_Overview/GraphicsTechnologies/GraphicsTechnologies.html#//apple_ref/doc/uid/TP40001067-CH273-SW1 Graphics Technologies]; and here's the technical/programmer's reference-guide, [http://developer.apple.com/library/mac/documentation/GraphicsImaging/Reference/QuartzCoreRefCollection/QuartzCoreRefCollection.pdf Quartz Core Reference]. Nimur (talk) 18:04, 17 March 2011 (UTC)

:What exactly do you mean by "handled"? I'm not clear what you're asking about. In general, on a Mac each application has only a single instance, and the applications manage their windows individually. You switch between windows by switching between applications. --Mr.98 (talk) 18:28, 17 March 2011 (UTC)

::I meant how do you tell what's open and switch between the different windows. I get it now. Thanks. --T H F S W (T · C · E) 21:22, 17 March 2011 (UTC)

:::It is a little different than Windows, as you can see. There are times when having all of the windows managed by individual applications is great, and there are times when it is maddening. --Mr.98 (talk) 01:21, 18 March 2011 (UTC)

Greetings,

I had Windows Vista on partition C: as the sole operating system on the computer. I created another partition (J:), and rebooted with the Windows XP installation CD inserted, which extracted the XP installation files onto the unallocated partition. When I rebooted, however, nothing happened; I had to use Hewlett-Packard's Vista restoration CD to have access to the Windows Boot Manager, which only detected Vista.

How might I boot the partition with the XP installation files on it, so as to finish installing XP? And once I'll have done that, how shall I be able to dual boot Vista and XP? Would I have to use a live CD to install GRUB?

Thank you so very much in advance for your answers,

88.189.248.66 (talk) 20:47, 17 March 2011 (UTC)

:Yes, some type of boot manager is one way to go. On the other hand, if you have more then one hard disk (not just partitions on one disk), you could put a different O/S on each of those and then switch the boot drive in the BIOS start-up menu when you boot (you normally have to hit some key to jump to that). This approach might be better if you only infrequently switch, since you don't have to answer boot manager questions each time or wait for a time-out. Also, if either disk gets corrupted, you can then boot off the other O/S and use that to try to fix the bad one. StuRat (talk) 00:58, 18 March 2011 (UTC)

:If the Windows Boot Manager now loads, you can simply edit its options to add XP as a boot option, you can do this by editing the boot.ini file in C: while Vista is loaded, or use run -> "msconfig", that utility will allow you to add XP as an option. Neoinr (talk) 03:17, 22 March 2011 (UTC)

Hello all. I have Windows Vista running with VMware Player as a virtual machine. I downloaded ObjectDock free, and the thing is just horrible. After downloading RocketDock, I tried to delete it, but it gives me a notice that says: "Access denied: you must have permission to edit this folder". How do I get permission? --T H F S W (T · C · E) 21:21, 17 March 2011 (UTC)

:Is your account [a] Standard [account]? If it is, try deleting it as an Administraitor, then see if you delete it. If you are still having troubles, make sure you are allowed to modify the folder, file etc. under propeties/permissions. General Rommel (talk) 04:18, 18 March 2011 (UTC)

::I'm not sure. How could I tell? And how do I delete as administrator? --T H F S W (T · C · E) 06:08, 18 March 2011 (UTC)

::: At Control panel/user accounts/manage accounts - what do you have? Is your current user with administrators rights? Adrian (talk) 07:40, 18 March 2011 (UTC)

:::: Yes, it is, but I still need permission. Permission from who, the surgeon general? --T H F S W (T · C · E) 17:14, 18 March 2011 (UTC)

::::: That`s really strange. I don`t know if I can help further online like this. Sorry, I don`t have any other ideas. Adrian (talk) 18:36, 18 March 2011 (UTC)

:When you say you tried to "delete" it, do you mean that you literally tried to delete the folder from Program Files? Did you try using the Control Panel's uninstall feature, or running the program's uninstaller from the Start Menu if it has one? -- BenRG (talk) 21:27, 18 March 2011 (UTC)

:Sorry for not responding, I mean, right click on the folder/fine, select properties and select security. I have to say though I cannot believe you can't delete the file. As suggested by Ben, have you tried running the programs uninstall program or tried uninstalling the program from the Control Panel? General Rommel (talk) 02:27, 20 March 2011 (UTC)