Were there ever instances of sailors pressed into British service in Europe ending up in the Caribbean?

Question: I am working on a story in which I wanted to include a character who was pressed into the British Navy in 1790's England, and ended up on a ship headed to the Caribbean.  This is a pretty integral part of the story, so I want to make sure that it was even something that would have happened.  Thank you in advance for your time.
Comment: @justCal: Villeneuve and Nelson chased each other to the Caribbean and back *en route* to Trafalgar, as Villeneuve attempted to shake Nelson off his tail
Comment: Linebaugh & Redikers "The multi headed Hydra" has a chapter or three on these kinds of transatlantic travels, IIRC - maybe your library has the book.
Answer: Sure, I see no problems with this, press gangs for the Royal Navy were still active, not ending until sometime between 1814 and 1853.
The British had a Naval presence in the Carribean. In the early part of the century for instance, mainly to deter the pirate threat, there were

Royal Naval vessels in the Caribbean, numbering 124 by 1718

The Royal Navy was engaged in war throughout the last half of the 18th century with every major power with colonies or interests in the Caribbean, the French, Spanish and Americans. The British also had their own colonies there as well, the British West Indies, so finding British vessels in the Caribbean is also historically accurate.
In fact if your sailor needs to be 'out' of the navy in the Caribbean, there is even history to back that up : The Hermione Mutiny
Answer: Yep, this is fine. In addition to mainland-based press gangs, the Royal Navy pressed merchant sailors including American sailors until the end of the War of 1812. The Carribean, of course, lies between Europe and North America, so perhaps an American pressed man would be particularly likely to end up there.
Comment: The Caribbean does not really lie between Europe and North America, especially not between Britain and the 13 ex-colonies
Comment: @Henry If you follow the [trade winds](https://people.hofstra.edu/geotrans/eng/ch2en/conc2en/tradewinds.html) from Europe to North America then the Caribbean is 'between' the two in terms of travel.
Comment: @SteveBird: *Running with the wind* is a level (un-heeled) and very comfortable point of sail, but the slowest point of sail. The next slowest point of sail is a *broad reach* just a few degrees off of straight downwind. Anyone in a hurry or not threatened with a marginally unseaworthy vessel will avoid these two points of sail unless they are the *straight-as-an-arrow* shortest path. The fastest points of sail are a *beam reach*, with the wind hitting the beam near a 90 degree angle.
Comment: I suppose it depends if you call Central America part of North America. It is, or that's how North America is usually defined.
Comment: @NeMo "The Carribean, of course, lies between Europe and North America" that must have been a _massive_ earthquake ....
Comment: I didn't say which part of North America :D


Why are some user agents still getting a meta robots tag with noindex from my site?

Question: A friend pointed out to me that a website is not in Google because of the presence of a
<meta name='robots' content='noindex,follow' />

tag in the home page. Ok, should be easy enough to turn that off, right?
Wrong.
Site uses Genesis framework, and in the SEO settings, none of the options are enabled to generate noindex.
Go to the individual page (homepage is a page, not a post), look there, none of the noindex options are checked there either.
Ok, one thing I do see, something is generating a robots.txt with disallow all. Not sure what is doing that, but it's not helping, so I upload a new robots.txt and remove write perms and now I can see my new robots.txt is remaining in effect that allows spiders.
Still getting that tag in the header though.
Then I think, has to be the coming soon plugin, (Soon) just being wonky, so disable that completely, still have the noindex tag.
(Then I remember I've never cleared the wp cache on any of these attempts, so do that....)
Then I find this Remove meta robots tag from wp_head
and realize wait, what? There's a blog_public wp_option?
Install phpMyAdmin so I can look, sure enough, blog_public = 0. EUREKA?
Set that to 1, reload in Firefox and Chrome, the noindex tag is gone (victory?)
Head over to Google webmaster tools, tell it to reindex and it's still complaining it won't because there's a robots tag with noindex
W-T-actual-F
In a shell, now...
lynx -source -dump https://mysite.example

<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
**<meta name='robots' content='noindex,follow' />**

Where on earth it that coming from? Considering I can still reload the page in FF or Chrome and that tag doesn't show up?
Answer: I was editing stuff in default-filters.php and then cleared my wp cache and it finally went away. Then I undid my change to default-filters.php and it stayed away.
So I'm inclined to think, this was a caching issue?


Any prayaschitta for people who have beaten up their parents?

Question: Is there any prayaschitta in the scriptures for people who have physically hurt  their parents? (Please do not assume things. I am asking this for a particular individual.)
Comment: @AnuragSingh Yeah people love to assume things about me without rhyme or reason.
Comment: Haha. **'Please do not assume things'**
Comment: I don't know about praschit but I heard earlier that Lord Krishna said to someone(don't remember whom) that if a person commit sin toward his parents. And their parents hasn't grant him forgiveness for that sin, then in that case even I(lord) am unable to remove that sin of him. Because parent's place is far greater than mine(Lord) also. So by this wordings of Krishna we can conclude that Until our parents don't forgive us, our all efforts of praschit will be useless. He also said that One who gives grief to their parents, they ended up by eating their own meat/flesh in hell as punishment.
Comment: @Rishabh Well the mother has forgiven. No father involved in the particular case.
Answer: Let me tell you a story.
Bharavi is a classical Sanskrit poet and literary genius. (My information says he was from Kerala). He was a child prodigy who was routinely praised by everyone who knew him/ knew of him. People praised him effusively to his parents. However, every time his father heard his son's praises he used to brush it off and negate it with a "oh he is just a kid; he is definitely not all that;has a long way to go" etc.
This went on for a long time. Bharavi grew extremely resentful of his father. He failed to understand why his father was casting a shadow on his genius and impeding his progress and reducing his glory. The resentment grew so much that he could not bear it any more and decided to eliminate impediments to his fame (i.e., he decided to take his father's life).
One afternoon, he lay in wait on the loft above his father's cot where the father usually came to nap after lunch. He had a big boulder with him and was going to drop it on his father's head when the old man drifted off to sleep. Soon, lunch was over and father came to lie on the cot. Mother came to him and sat on the cot and offered him tamboolam. She started talking (Bharavi was obviously listening). She said " Why do you disparage our son. How can you not see his genius when everyone else is able to. Why do you insist on hurting him and making him feel small". Father replied " Dear, how can you not know that our son's progress is a matter of pride and achievement for me. However, do you also not know that elders praising children results in shortening of their lifespans (AyuHkShINam)? I cannot bear for my son to suffer thus. All the elders praising him pains me for this reason. I want our son to have a long life and for his genius to further increase and for his fame and glory to spread much further. This is why I try to counter the negative effects of all the elders' praises."
Bharavi is listened silently and could not stop weeping. He immediately  came down and fell at his father feet. He confessed his intent to kill his father and begged for his forgiveness and reparations. Father felt very sad. He went silent for a minute, opened his eyes and said to Bharavi "Go to your father-in-law's house. Live there for a whole year. Do not leave their house under any circumstances".
Bharavi took his parents' blessings and set off. He was received with great joy and respect. He was treated like a king for the first week. Gradually as they saw no signs of his leaving, they slacked off with the adoration and waiting hand-and-foot. Weeks turned to months. Not only was there no good treatment, he was put to work in the house like a member of the family and later like a servant. The situation deteriorated to such an extent that he was finally made to work in the cowshed cleaning up animal leavings inter alia.
Bharavi stoically bore all this ill-treatment, introspected, cleansed his soul of the dushkarma  and during this period in the cowshed produced one of the 5 mahakaavyas in Sanskrit, viz, "kirAtArjunIyam".
Moral of the story - the person must ask the parents for suitable punishment. Bharavi's punishment broke his ego(which caused the dushkarma) to such an extent that there was no other way but to give birth to a pure, cleansed being.
Comment: _"person must ask the parents for suitable punishment"_ But in case (as op said in comment) if parents did forgive him on his apologies then why they will give punishment to their son/daughter since they already forgive him/her? If child got forgiveness on apology then what question has left for asking the punishment since he/she already being forgiven by parents?
Comment: @SuryaKantaBoseChowdhury Bharavi's father also forgave him immediately. Bharavi insisted on going through a purificatory process so his father devised a suitable one for him.
Comment: The particular person has already been forgiven by his mother.
Comment: actually, the father says 'stay at your in-laws place till your mother-in-law serves you salt with her left hand' - meaning after a long while, she stopped serving him, and sat by his side and ate.
Comment: @ram My source says 1 year. So...
Comment: maybe both could be right and it took a year for her to serve with left hand
Comment: @ram - possibly. although my interpretation is he would not even have been given as much respect as being allowed to eat with family.


Is there a Bitcoin ATM in London?

Question: Now I know there is one Bitcoin ATM in Vancouver, Canada. Is there a Bitcoin ATM in London? If yes, where is it located?
Answer: There will be Robocoin ATM's in London and Bristol this Spring. https://twitter.com/satoshipoint
Answer: No, there is not Bitcoin ATM in London. There are only two ATM machines at the moment. One in Canada and the other one about to go live in Hong Kong. Brazil is getting one soon.
But there are currently "human ATM's" in London via local bitcoins. They will buy and sell Bitcoins. Just meet up with one of them at your favourite pub.
In case you see business opportunities and want to start your own check https://robocoinkiosk.com and https://lamassu.is/ or DYI and build it!
Answer: There are currently 2 Bitcoin ATMs in London, you can find them listed here http://coinsonar.co.uk/

Is there a Bitcoin ATM in London?


Keyboard and mouse is not working properly

Question: I am having some weired problem regarding mouse and keyboard. I am using a laptor with a external mouse. When i scroll my mouse it worked in reverse way. And when i am typing with my keyboard it stop working for few moment. If i typed two later repeatedly it missed to draw the 2nd letter. Backspace is not working properly either. It need 4 stock to remove a letter. Help please
Answer: Salam. Go to all settings and see carefully all and their tabs. I think it was a choice in "universal access" tabs same as "stop mouse when i use keyboard". I unchecked this before, but I forgot where it was. excuse me.


Negative Definite vs Semi-definite Hessian - Sufficient vs Necessary conditions?

Question: When a Hessian matrix is negative definite at a critical point then that critical point is a local maximum (Sufficient Condition).

As per the calculus wiki:
Link, when the Hessian is negative semi-definite then, we can only conclude that it is not a local minimum. This seems to suggest that negative semi-definiteness is a necessary condition, not a sufficient one.

Can anyone provide an example of a multiple variable function where we have a negative semi-definite Hessian but not a local maximum? As per my thinking, if we evaluate the hessian to be negative semi-definite at the critical point it must also be a local maximum, but clearly calculus wiki disagrees.
Answer: The simplest example is $-x^3$ in the single variable case, or $-x_1^3-x_2^3$ in the case of two variables. The Hessian matrix is negative semi-definite at $(0,0)$, but there is no maximum at this point.
Comment: I see. So it is indeed a necessary condition not a sufficient one. Could you refer me to a method of further inspection to verify that the critical point is indeed a maximum if we have negative semi-definiteness (a non-graphical one).
Comment: @Kinno: Yes, the mere finding of a negative semi-definite Hessian does not imply that there is no maximum at this point. Consider $-x_1^4-x_2^4$ for instance, whose Hessian is nsd at $(0,0)$. Hmm, I am not sure that there is a general method allowing you to conclude in all cases. I would recommend to go back to the definition of a maximum and try to study whether $f(x_1,x_2) \leq f(x_1^*,x_2^*)$ for any $(x_1,x_2)$. In our example  $-x_1^4-x_2^4 \leq 0$ and so $(0,0)$ corresponds to a global maximum of $f$, even though the Hessian is not negative definite at this point.
Comment: Great thank you. I have a feeling this might have to do something with establishing concavity at the intervals on the side of our critical point. Regardless, I will look further into it.


Who need to do the Garuda Purana pooja?

Question: Who all need to do or read the Garuda Puranam pooja.
What all are the instructions that we need to follow while doing, and after doing that. What age people can to do this.
What is the purpose of Garuda Purana .
Answer: Not much is said on this topic as it concerns the delicate topic of death. This might answer some of your questions:

What is the significance of Garuda Purana after death?
Sri Sri Ravi Shankar: Garuda Purana is all about the life after death.
  How the soul goes, where, what and all that. There is only certain
  time when you are supposed to hear that, (the few days after the soul
  leaves the body) listen to it so you know where the departed soul goes
  and what happened to them. There are a lot of things in Garuda Purana.

http://www.artofliving.org/2-august-2011-qa-1

Who need to do the Garuda Purana pooja?


adaptor for 1994 Mazda B2300 P/U

Question: My engine light comes off and on, I bought a DIAGNOSTIC SCAN TOOL (CAN OBDll) to check the engine light, as per Mazda book it shows in the diagram from my eec test plug to connect system selector tool 49-b019-9a0 to the data link connector. Then connect self diagnosis check tool 49-h018-9a1 to the system selector and a ground. My new tool has 16 pins where can I find and buy the proper tools that I need to diagnose this problem. Help would be greatly appreciated and if you have these tools I would
Answer: The Mazda B series trucks are rebadged Ford Rangers. In 94 the Rangers were still OBDI (1).
To read the codes and look at the data you need something like this.
http://www.amazon.com/INNOVA-3140-OBD2-OBD1-Scan/dp/B000R3SNJU
To just read codes you need something like this, it's cheap but a pain the but to use. http://www.amazon.com/Actron-CP9015-Ford-Code-Scanner/dp/B0006V2BGY

adaptor for 1994 Mazda B2300 P/U


Why do Matthew and Luke contain genealogies of Jesus, while Mark and John do not?

Question: Both Matthew and Luke contain genealogies of Jesus, Matthew to Abraham, and Luke to Adam.  However, neither Mark nor John contain genealogies.  What is the reason for this--both for why Matthew and Luke do contain genealogies, and for why Mark and John do not?
Comment: Neither Mark nor John contain any mention of the birth of Jesus, ergo, no genealogies.
Comment: Probably because Matthew was a tax collector and Luke was a doctor. Both of them found details to be of utmost importance? Mark provides a general overview of Jesus's life whereas John only focuses on his ministry so the whole genealogy wouldn't make sense in these two books.
Answer: I don't think we can ever know for sure as we can't ask them. However I think the answer is probably to do with who they are writing to and what is the purpose of their writing.
Matthew is probably writing to a Jewish audience. For them the Christ has to have come from Abraham & David and so Matthew spends the time to show that Jesus has the credentials to be the Christ.
Luke has probably been employed to write the book by Theophilus (debated if that is the persons name or title). He has been tasked to report on what has happened and what it means - thus it goes into a lot of detail.
Mark seems to be focused on just reporting the facts as they happened. He doesn't need to present the background information on what it means, just runs through the events.
John is in a completely different format than the other gospels. In terms of who Jesus is he is very much focused on Jesus' divinity - not his human family.
Answer: Matthew
The Gospel of Matthew appears to be written to Jews in order to present Jesus to them as the King of the Jews.  As such, it was necessary to trace Jesus' lineage through Joseph, His adopted father, through the lineage of the kings back to David, whom God promised would have an heir who would reign forever.  It was also important to trace His lineage back to Abraham, the Patriarch.  As the son of Joseph, Jesus had legal right to the throne.
Mark
The Gospel of Mark presents Jesus as the Servant who fulfills the Suffering Servant prophecy in Isaiah 52-53.  For a servant, a genealogy is unnecessary and even irrelevant.  Thus, Mark does not include one.
Luke
The Gospel of Luke presents Jesus as the Son of Man.  As such, it is thought that he actually traces Jesus' biological lineage through Mary.  Her lineage leads to David as well.  However, Luke's emphasis is not the Jewishness of Jesus, but His human nature.  As such, he traces the lineage all the way back to the first Adam.
John
The Gospel of John is said to present Jesus as the Son of God.  As such, God has no genealogy.  His authority does not come from the legal line of David or in His Jewishness, but in His divinity.  Jesus' Divine nature has no genealogy.  He is, forever has been, and forever will be the Son of God and God the Son.
Comment: The only thing I would add is that John does in a way have genealogy.

John 1:1  In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God.

This is God's genealogy, pre-existance.
Answer: This point has been touched on, but I wanted to flesh it out a bit.  The lack of genealogies in Mark and John is intentional.  Mark portrayed Christ as a Servant, which was stated already, and as such the author intentionally left out the genealogy.  John HAS a genealogy, if God can be said to have one... "In the beginning was the Word."  He always was, and always will be.  All four Gospels are making a point about some aspect of Christ's "origin."


Calendar month in property letting (UK)

Question: A tenancy agreement gives the end date of the tenancy as being on the 30th of a month, where the month has 31 days. The rent is stated as being amount x per calendar month. Is it right, therefore, that for the final month, only (30/31)*the monthly rental amount is paid, or does the definition calendar month mean 30 days (as other calendar months only have 30 days in? Would be great if someone could clarify this for me!
Answer: If you pay rent per calendar month, you pay the same amount each month on the same date. In your case, the 30th.
The rent is calculated by dividing the total for the year by 12, or by multiplying the weekly rent by 52/12 (4.3 recurring).
You don't pay for 31 days in January, 28/29 in February, 31 in March, 30 in April etc.

Calendar month in property letting (UK)


Using a digital camera ( Canon) as webcam

Question: I can't use my digital camera ( Canon ixus 160) as webcam
is there an application for that ?
or just in the settings?
Comment: Add more info. You must be getting some error or something.
Comment: Are there any clues in the manual that this is possible? A similar question has been asked before http://askubuntu.com/questions/53889/use-old-usb-digital-camera-as-webcam but it was closed (for no good reason imho). Also something like that is done in this http://www.moreno.marzolla.name/software/linux-webcam-server/ tutorial.
Answer: Here's another solution.
List of gphoto2 supported cameras: http://gphoto.org/proj/libgphoto2/support.php
You need install gphoto, v4l2loopback-utils and ffmpeg.
Then
sudo modprobe v4l2loopback

and
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video1

Now you have webcamera from your digital camera.
Comment: I get this error (cut at top):
Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1056x704, 25 tbr, 1200k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> rawvideo (native))
[swscaler @ 0x559c14f77de0] deprecated pixel format used, make sure you did set range correctly
[v4l2 @ 0x559c14f42fc0] ioctl(VIDIOC_G_FMT): Invalid argument
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 --
Conversion failed!
➜  ~
Comment: It worked for me... but the resolution is 1056x704. Is it possible to change it to a 16:9 resolution, such as 720p? I am using a Cannon T3i and this option is available on Entangle... however I don't know how to change your command to switch to a different aspect ratio
Comment: @noreabu if you have other webcams, the `/dev/video1` may not be the loopback device. You can check type of devices with `v4l2-ctl --list-devices`
Answer: This can be done but requires a number of steps. First, you must install gphoto and v4l2loopback-utils.
sudo apt-get install gphoto2 v4l2loopback-utils
Plug in your camera via USB (when the camera mounts automatically, unmount it). Then run gphoto2 --abilities to see if your camera is capable of doing this. Here's the output when connecting a Canon EOS 1200D

Then run sudo modprobe v4l2loopback to activate the kernel module needed to create a video device from your camera.
I've seen older tutorials on this task that use gst-launch-0.10 to achieve the next step of this task (e.g. this one). I am using Ubuntu 17.04 which uses gst-launch-1.0. Below is the updated command to create a video device from your digital camera:
gphoto2 --stdout --capture-movie | gst-launch-1.0 fdsrc ! decodebin3 name=dec ! queue ! videoconvert ! v4l2sink device=/dev/video1
This will create a video device in /dev/video1, which you can now use in programs like VLC.
If you see any errors about the device being in use you need to kill the gvfs-gphoto2-volume-monitor process by running killall gvfs-gphoto2-volume-monitor.
Comment: I get this:
`➜  ~ gphoto2 --stdout --capture-movie | gst-launch-1.0 fdsrc ! decodebin3 name=dec ! queue ! videoconvert ! v4l2sink device=/dev/video1
Setting pipeline to PAUSED ...
Nehme Vorschaubilder als Film in 'stdout' auf. Drücke Ctrl-C zum abbrechen.
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0: »/dev/video1« ist kein Wiedergabegerät.
Additional debug info:
v4l2_calls.c(642): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0:
Capabilities: 0x5200001
Setting pipeline to NULL ...
Freeing pipeline ...`
Comment: Try /dev/video2
Comment: @noreabu sounds like a bug that you should report
Comment: This worked via the ffmpeg answer above. I had to use `guvcview` to see the output
Comment: I'm getting `modprobe: FATAL: Module v4l2loopback not found in directory /lib/modules/4.15.0-36-generic`
Comment: I confirm this works well on Ubuntu 18.04 with Canon 70D. The only difference is that the device is not created by the `sudo modprobe v4l2loopback` command  in `/dev/video1`, but in `/dev/video0`. Anyway, thanks a lot for the answer! :)
Comment: Beware, the older cameras like Canon 70D limit time they can have the sensor switched on becuase it produces quite a lot of heat. On my Canon 70D, it's 30 minuts, so it's not usable for longer video calls.
Comment: I'm using a Panasonic HC-V777 on Ubuntu 18.04. When unmounting the camera and querying `gphoto2 --abilities` I get `*** Fehler (-105: »Unknown Model«) ***`. Do I have to report my camera as unsupported to the gphoto devs? On http://gphoto.org/proj/libgphoto2/support.php it says `If it a USB mass storage based camera (appearing like a USB stick or USB drive) it is mounted by your operating system and not gphoto2. In this case a report to us is not necessary.` And my camera does get mounted like a mass storage device.
Comment: I posted a solution for unmounting your camera, if unmounting doesn't work via nautilus: https://askubuntu.com/questions/1265670/
Answer: I was able to get video & image recording with a Canon DSLR 600D
sudo apt get install guvcview ffmpeg gphoto2 v4l2loopback-dkms v4l2loopback-utils ffmpeg
Plug in camera, any mode seemed to work, test with the basics:
Prep
sudo modprobe v4l2loopback
killall gvfs-gphoto2-volume-monitor

Test
lsusb
gphoto2 --auto-detect
LANG=C gphoto2 --summary
LANG=C gphoto2 --list-all-config

Try
gphoto2 --capture-image
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video1

Visualize  (in another terminal)
guvcview
or
guvcview-brlin.guvcview
You can try different /dev/video1 commands
There's also EOS Movie Recorder
Unzip this: https://sourceforge.net/projects/eos-movrec/files/eos-movrec/0.3.3_beta/eos-movrec-0.3.3_beta.zip/download
cd eos-movrec-0.3.2_beta
sudo apt install libgphoto2-dev
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make

Comment: thanks. i use this and then capture the window in OBS "gphoto2 --stdout --capture-movie | ffplay - "
Comment: Thank you for this. Is it possible to access the camera microphone at the same time (and make it an accessible device)?
Comment: OBS has microphone capability, and plugins that can expose the whole setup as a webccam too
Answer: I found this very useful for me and it did work with my Canon 5D Mark 3
How to use you DSLR camera as a webcam
OBS is a great tool for live streaming and recording a presentation or training. It can also be used to create a virtual webcam to act as input to tools such as Jitsi, Skype and Zoom. Lots of us have good DSLR type cameras, and these can act as a webcam for input to OBS (and any other tool that can use a webcam source). This allows  you to use a high quality camera for the video input, and gives you the full control that you get with a digital camera. In this video, I show you how to use pretty much any camera as a webcam for OBS without any special software or hardware adapters. All you need is a camera and a USB cable. This is achieved using the combination of gphoto2, ffmpeg, and v42loopback.

Make sure your camera make and model is supported. You will find a list of cameras supported by this method at
http://gphoto.org/proj/libgphoto2/support.php
Fortunately, my Canon cameras are all supported. You will need a supported camera and a USB cable to connect the camera to your computer.

Set your camera so that it does not automatically power off. On my Canon 6D Mark ii this is "Auto power off: Disable" on the wrench screen 2.

If you have back-button focus enabled, you need to set focus back the the half press of the shutter key. If you use back button-focus you already know how to do this. If you leave back-button focus on, you will get errors relating to shutter button half press.

If you don't have gphoto2 installed, you need to install it first.
sudo apt install -y gphoto2

If you don't have the video loopback driver installed, you need to install it first.
sudo apt install -y v4l2loopback-utils

If you don't have ffmpeg installed, you need to install it first.
sudo apt install -y ffmpeg

Plug in your camera via USB (if the camera mounts automatically, unmount it) by selecting it in your file manager (Nautilus if you are using Gnome) and right click, and select "Unmount" from the popup menu.

Enable and determine the virtual video device
First unload v4l2loopback so you can determine which device it is creating.
sudo rmmod v4l2loopback

Ignore any errors.

List all video devices so you know which one is next in line
ls /dev/video*
You will see something like
/dev/video0  /dev/video1
which indicates video devices already on my computer. If you see nothing here, then you have no video devices.

Activate v4l2loopback
Run
sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2

to activate the kernel module ('loopback driver') that enables the creation of a video device from your DSLR camera.

List all video devices so you know which one is the one to use
ls /dev/video*
You will see something like
/dev/video0  /dev/video1  /dev/video2
The last one will be the one used by the loopback driver, in this case video2.

TESTING
Now you can do some testing using gphoto 2.
List auto-detected cameras and the ports to which they have been connected.
gphoto2 --auto-detect

You will see something like:
Model                          Port
----------------------------------------------------------
Canon EOS 6d Mark II           usb:001,013

Capture the video and pipe ot out to the virtual webcam device
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2

That is it. Now you can go and add it to your source in OBS.

All simple, and all free thanks to Free and Open Source Software.
Comment: Same comment as earlier. Is it possible to access the camera microphone at the same time (and make it an accessible device) ?
Comment: Thanks for this awesome tutorial. It works flawlessly on my EOS 6D. How do I make autofous work?
Comment: Thanks, key was activated v4l2loopback with parametrs max_buffers and exclusive_caps


What's God's purpose David was talking about in psalm 57:2

Question: Psalm 57:2 says, "I cry out to God Most High, to God who fulfills his purpose for me." This is key in understanding God's purpose for your life. God has numbered your days and will fulfill every purpose He has for you. What is God's purpose David was talking about?
Comment: KJV '_that performs all things for me_' YLT '_who is perfecting for me_'
Answer: In the beggining of that Psalm, we can read in NASB

Prayer for Rescue from Persecutors.
For the music director; set to Al-tashheth. A Mikhtam of David, when he fled from Saul in the cave.

This was a prayer for aid. Why would David need aid? As the beginning also implies, David fled from Saul to a cave (1 Samuel 22:1-2).
Given the context, the purpose God would accomplish for David could be protection from his enemies and/or vengeance.
Answer: English Standard Version

I cry out to God Most High, to God who fulfills his purpose for me.

It is important to point out that the word "purpose" is not in the original Hebrew.
New American Standard Bible

I will cry to God Most High, To God who accomplishes all things for me.

who fulfills
גֹּמֵ֥ר (gō·mêr)
Verb - Qal - Participle - masculine singular
Strong's Hebrew 1584: To end, come to an end, complete
His purpose for me.
עָלָֽי׃ ('ā·lāy)
Preposition | first person common singular
Strong's Hebrew 5921: Above, over, upon, against
Not only the word "purpose" is not there, but also there is not even a noun. It is up to the translators to fill in the blank: God fulfills/completes/accomplishes ___ for me.
A similar occurrence is in Psalm 138:8a:
New International Version

The LORD will vindicate me;

English Standard Version

The LORD will fulfill his purpose for me

There is plenty of room for ambiguity here. David might not have been talking about a specific purpose in this verse. The rest of the psalms bear this out.

3 He sends from heaven and saves me, rebuking those who hotly pursue me ...
4 I am in the midst of lions; I am forced to dwell among ravenous beasts  ...
6 They spread a net for my feet—I was bowed down in distress.
They dug a pit in my path—but they have fallen into it themselves.

It is just a general sense of God's protection over David so that he could finish his jobs.

What’s God’s purpose David was talking about in psalm 57:2


Principle of Least Action Question

Question: Let's say we have a particle with no forces on it. The path that this classical particle takes is the one that minimizes the integral
$$\frac{1}{2}m\int_{t_i}^{t_f}v^2dt.$$
So if we graph this for the actual path a particle takes it is a straight, horizontal line on the $(t,v^2)$ plane. But couldn't we lessen the integral if we first slow down and then speed up near the end to create a sort of parabolic line that has less area under the $(t,v^2)$ plane? So why doesn't the particle take this path? What am I missing in my thinking?
Answer: You have to minimize the integral subject the the constraint that the initial and final positions $x(t_i)$ and $x(t_f)$ are held fixed.  In particular, $\Delta x = \int_{t_i}^{t_f} v(t)\, dt$ is held fixed.  If the particle slowed down than sped up as you suggested, the action would be less, but it wouldn't have a high enough average speed to cover the full $\Delta x$ in time.  You can play around with a few specific trajectories and check for yourself.
Comment: @GavinN. This is "arm-wavy" math, but it shows the basic reason why your thinking doesn't work: suppose you do some part of the path with velocity $v - \Delta v$ and another part with $v + \Delta v$. When you square those velocities, you get $v^2 - 2v\Delta v + (\Delta v)^2$ and $v^2 + 2v\Delta v + (\Delta v)^2$. The $\pm 2v\Delta v$ parts of the action might cancel out, but *the two $(\Delta v)^2$ parts don't cancel, they add.*
Comment: @GavinN. It would, but the time you spent going fast would get weighted heavily (because of the $v^2$) so you'd end with more action than if you'd traveled at the constant speed.  If you think I'm wrong, please suggest a specific trajectory that has less action than a constant trajectory with the same average speed.
Comment: Why not? If you graph both of the possible $(t,v)$ paths you have the right path being a horizontal line and then you could have the other path go up and down and back up with 1 "node" and 2 "antinodes" that has the same area under the curve that satisfies your position. With regard to the average velocity, if I drive 10000 mi/h to right before the finish line and slow down to .000001 mi/h or however slow and wait to have the correct average velocity wouldn't that satisfy the condition?
Comment: Ya I calculated some paths and I see what you guys are saying now. that is a good way of seeing it too alephzero.
Answer: You're missing that Dirichlet boundary conditions
$$ x(t_i)~=~x_i  \quad\text{and} \quad x(t_f)~=~x_i $$
are implicitly implied. The stationary action principle is not well-posed without boundary conditions.
Comment: I'm not sure what you mean, what about my proposal violates this?
Comment: Your proposal does evidently not observe the boundary conditions. You cannot just reduce the speed in the middle without consequences. Something has to give.
Answer: Your proposed path has a VERY LARGE action. As @tparker pointed out, you have to minimize the path subject to the constraint that the average velocity doesn't change. Now, the action is quadratic in velocity. A little fiddling around with the math should convince you that to minimize the integral of $v^2$ subject to the constraint that the average velocity doesn't change, you want the velocity to be constant. Intuitively, going fast for a bit raises the action a LOT (because velocity is squared) while going slow for a bit doesn't do much to lower the action (because velocity is squared).

Principle of Least Action Question


What DAL are Humans?

Question: I am no expert at the Development Assurance Process, but hypothetically speaking what Design Assurance Level (DAL) would a human pilot receive if they were classified as one (i.e. DAL A, B, C, D, E). It seems absurd to try and answer this question since the plane can't even leave the gate today without a pilot or pilots, but I am hoping to learn more about the DAL process thru any answers received.
Comment: "It seems absurd to try and answer this question..."  I agree.
Comment: Come on, at least tell us what DAL means.
Comment: @quietflyer see the DO-178 specification for definition of DAL (or quick summary here https://en.wikipedia.org/wiki/DO-178C)
Answer: I'm oversimplifying a bit, but more or less the DAL level of a piece of software is decided by asking the question, "What is the worst that could happen if this software fails to operate as designed?"  Note that "failure" in this case could mean that it simply stops working, but it could also mean that it does the wrong thing, like pitch up when it should pitch down. So for example,

The software that runs the in flight entertainment system.  Worst thing that could happen has no safety effect whatsoever, therefore level E.
The software that runs certain cockpit indicators, like the engine vibration display or engine oil temperature display: Usually considered a "major" safety effect, but not more than that, so level C.
The software that controls the engine thrust: if that fails to set the thrust according to the pilot demand, that could result in the plane crashing, so "catastrophic effect", thus level A.

It may be a little subjective, but I'd say that if we consider the pilot to be "software", if the pilot fails, the worst thing that could happen would be "Catastrophic" condition, and thus I would label the pilot as level A software.
Edits: clarified that DO178 applies specifically to software
Comment: "In flight entertainment system. Worst thing that could happen" - [Swissair 111](https://en.wikipedia.org/wiki/Swissair_Flight_111)?
Comment: @Zeus Swissair 111 was a wiring problem. In that particular case, that wiring *happened* to be for the IFE system, but the exact same problem could in principle have developed with any other wired system. Therefore, if anything, it stands to reason that you should apply the same reasoning at least to any wiring carrying significant voltage or power.
Comment: @Zeus interesting, I was unaware of that one.  In any case, DO-178C only applies to software.  There are separate regulations governing hardware. i.e. flammability and electric wiring don't fall under DO-178C.  I'll edit the answer to be more clear on that.
Comment: @aCVn, true, of course, but it shows that it's dangerous to think (and state unconditionally) in that vein. The _system_ has to be considered as a whole. We can even speculate what could happen from a software bug, assuming correct wiring: say, an infinite loop causing excessive power consumption for all seats at once -> failure of circuit breaker -> shedding of more critical load.

What DAL are Humans?


Farewell pizza for coworkers

Question: I am leaving my company and I am throwing a farewell party. It appears that there is no problem from the culture of my company, but I am wondering if it is a good idea to pay for my own going away party (ie, buying pizza). I would like to leave on good terms, with my coworkers and employer, would this be a good idea?
Comment: Ummm, sure?  Why would you think that you couldn't buy pizza for the team?  It would be more normal for the team to throw a farewell party for the departing individual.  But nothing says you can't have two farewells and no one has ever complained about someone offering them free pizza.
Comment: Ask your manager -- the custom may be that they buy -- but generally there's no problem if you want to feed the group.
Comment: Sound good. I instead buy a flower for all my coworkers the day I end my intership. Different color diferent meaning.
Comment: What country are you in? Here's nearly the same question: http://workplace.stackexchange.com/q/46276/2322
Answer: I think it would be a lovely gesture. You see, it's not too often that the departing worker buys the cupcakes or pizza. Usually the manager buys it for the departing employee. But in this case, it'd work out Ok if you had pizza + more.
So you'd get brownie points. It could possibly lead to some future gains, also.
So yes. Pizza is good.
Comment: I'd definitely agree with this - it's not about the reference (as suggested in another answer, it's about saying thank you to your team, and they'll likely give you a leaving gift anyway... so you'll probably break even. It won't necessarily have any major gain, but it's nice to leave as friends and it may mean you're remembered more strongly in the minds of co-workers: say if they're asked if they know any other `whatever job you have`'s
Comment: +1, however check with your HR director first.  You never know what there policies are.
Answer: Definitely
In case, your co-workers are coders, then they would remember you for life. (If you add coffee in the treats list, then you've struck the chord there!)
If not, then still you would be remembered, everyone loves pizza.
On a serious note, I would also advise you to have a nice talk(about anything) with all of them before you leave, so that they would be happy to come forward to offer help in the future (or maybe future gains too like @Adel wrote).
Answer: I'm going to go against the grain here and say this sounds horrible. If you have to "buy" (so to speak) your way to get good references then there is a serious problem here. What I think is going on here is that you're excited to leave and you're not thinking straight. My advice is if this costs you more than 25 dollars, I would pass as it seems a bit too excessive just to get a reference.
Comment: I think you're missing the point. The OP isn't suggesting that they have to do this in order to get a reference, they're asking if it's culturally accepted generally.

Farewell pizza for coworkers


How to compare goverment bonds to generic money market position?

Question: I know that the bonds are higher risk investment so I'd like to compare the bond funds/ETFs with the market sweep offered by account to decide on proper mix. However I'm confused of how to read ETF prospect about expected return - what number is the expected return (i.e. barring the change in interest rate, default etc.) in dividends (assuming no change in interest rates I guess)?
Comment: This seems like kind of a complex "question". You may want to focus it more.
Comment: @TylerDurden I tried to focus it more but it's possible I don't know enough to ask the right questions.
Answer: Bonds might not be simple, but in general there are only a few variables that need to be understood: bid, coupon (interest) rate, maturity, and yield.  Bond tables clearly lay those out, and if you're talking about government bonds a lot of things (like convertibles) don't apply (although default is still a concern).
This might be overly simplistic, but I view ETF's primarily as an easy way to bring somewhat esoteric instruments (like grain futures) into the easily available markets of Nasdaq and the NYSE. That they got "enhanced" with leveraged funds and the such is interesting, but perhaps not the original intent of the instrument.
Complicating your situation a bit more is the fee that gets tacked onto the ETF. Even Vanguard government bond funds hang out north of 0.1%. That's not huge, but it's not particularly appealing either considering that (unlike rounding up live cattle futures), it's not that much work to buy US government bonds, so the expense might not seem worth it to someone who's comfortable purchasing the securities directly.
I'd be interested to see someone else's view on this, but in general I'd say that if you know what you want and know how to buy it, the government bond ETF becomes a lot less relevant as the liquidity offered (including the actual "ease of transacting") seem to to be the biggest factors in favor. From Investopedia's description:

The bond ETF is an exciting new addition to the bond market, offering
  an excellent alternative to self-directed investors who, looking for
  ease of trading and increased price transparency, want to practice
  indexing or active bond trading. However, bond ETFs are suitable for
  particular strategies. If, for instance, you are looking to create a
  specific income stream, bond ETFs may not be for you. Be sure to
  compare your alternatives before investing.
Comment: +1 though added bonus of ETFs though is diversification. I presume that bond ETF has a wide range of maturity dates in them so $100 or so do create effectively a bond ladder. On the other hand in case of manually created bond ladder you need to invest more. That may be a problem for accounts with limited resources - for example using recommended on Investopedia minimum for bond ladder you need to contribute for 2-6 years to IRA/HSA full amount and spend all of it on bonds (probably unwise split of stocks/bonds at the beginning).
Comment: @User I just think, boiled down, if you're at that level where you're comparing yields and time horizons it's going to be hard to justify the fee. I think bond ETFs sit more correctly with someone who is sitting on a retail brokerage account and can pick from (a) stocks (b) a 0.0000001% interest rate cash account and (c) bond ETFs. Not a lot of thinking involved, quick to do, easy to get out of. By the sound of your analysis you're more sophisticated and don't get much of the abstraction offered by the ETF instrument.


Southwestern Mandarin: what does 欛新床/铺新床/压床 imply?

Question: 欛新床
《成都方言》

喻指小男孩或未婚男青年睡新床:~又叫"压床"。亦作"铺新床"。

Why only boys? or unmarried men? What sort of implications are buried in this word?
Comment: unmarried men, and younger than bridegroom, there are somethings bridegroom can tells this boy to help him being an adult.
Comment: Suggested edit: there's nothing to do with a language. It's more about asking a cultural customs
Answer: What needs to be understood here is that 欛新床 or 铺新床 is not just talking about making a bed or changing the sheets - but is specifically referring to Chinese wedding customs where the "new bed" is made for the newlywed couple.
Baidu 百科 has the following article: 压床(民间婚庆习俗) which explains:

压床又称压喜床,压新床等,中国汉族婚俗之一。青年男女结婚的头天晚上,新郎家要请儿女双全的老人把床铺好,然后新郎请一个或者两个弟弟和自己一起在新床上就寝。压床的人也有条件限制,不是任何人随便就能压的。首先,压床的人必须是小于新郎的青年,一般都是自己的亲弟弟,或者是叔伯弟弟和姨表弟弟。如果在自己的亲戚范围内没有这样的人选,新郎也可以找同村的朋友和要好的同学。压床人的第二个条件,必须是未婚青年。

The night before the couple-to-be get married, the entire family is supposed to make their bed after which the groom will chose one or two of his younger brothers to have a sleep over. The persons that the groom may choose from is limited, not just anyone can spend the night with him. First, the person must be younger than the groom, usually he will pick his own fleshly younger brother or his younger male cousins. If none of his relatives are applicable, the groom may find a friend or classmate from his town. The second requirement is that the person must be unmarried.
The article also states:

对娶亲的人来说,压床是一件吉利的事情。

This custom is thought to bring good luck to the new couple.
and don't forget:

如果男孩儿在压床的时候,不小心尿在了新床上,这是吉利加吉利,人们更是欣喜异常。

If during this custom the boy chosen to stay with the groom accidentally pees on the bed, this is considered luck upon luck and people will be even more delighted.
Answer: This custom is about the offspring of a new couple, especially to have boys in the future. In the past, only male members of family could inherit property. This is the reason why it is a boy.
Before marriage, each couple would have a new bed in their room. There is a ceremony to fix the bed in the room. After this ceremony, no one touch this bed before marriage except asking a boy to piss to an urn on the bed. It symbolises that a baby make bed wet. Nowadays, a boy jumps twice and eats nuts on the bed instead. This prompts the new couple to have baby as soon as possible, and have many offspring in the future.


Who do I contact to have the property line marked?

Question: I'm looking to install a fence on the property line, and I was wondering who do I speak to about having it marked?  Thanks!
Comment: Just an aside, usually, you aren't allowed to install a fence right on the property line.  It typically needs to be at least 1 foot inside your property.
Answer: The official answer is find a local land surveyor and hire them to do a property survey.
However, you can do a bit of research on your own, and may be able to figure out where the property lines are well enough to get by without hiring a surveyor, which can cost $250-1,000+, depending on the size of your property and how complicated the boundaries are. Note that you and you alone will be responsible for the cost of moving your fence if you get it wrong though.
Property corners are usually marked by a piece of rebar driven vertically into the ground. There's often a brightly colored plastic cap on top as well. If you're lucky, the text description may even be legible.

You can get a good idea of where to start looking by getting a copy of your plat at your local courthouse.
Tools you'll need:

metal detector (or a very strong magnet on a stick, as DMoore suggests)
shovel (I'd recommend a drain spade, but you can get by with most any shovel)
compass
100' tape measure

Then go about finding your property corners. They should be fairly easy to pick up with even a cheap metal detector, as they usually aren't buried very deep, and are made of a giant metal bar. Try triangulating off of known features, like curb or street corners. Roads often have centerline markers embedded in them as well that you can reference.
To keep from having a bunch of obvious holes in your yard, cut a plug of soil around the suspected marker location by digging the shovel in a circle to cut the sod.
Source: I used to be a land survey technician for a few summers in college.
Comment: Yes.  I use a stud finder magnet taped to a stick.  Sounds ghetto but find the bars in a few minutes.
Comment: @DMoore That's a genius solution! Sure beats buying a $50+ metal detector.
Answer: Depends how obvious it is.
If there are clear markers (stone bounds, iron pipes, etc) just walk out and pull a string between them. Your deed should describe the corner markers, though they can be tricky to find if you don't know what you are looking for. A stone bound, incidentally, is usually about a 3x3 or 4x4 inch square(-ish) chunk of stone - it may have a hole drilled in the top surface for fancier jobs to mark the precise corner. It may be down at ground level and covered with grass, or it may stick up a few inches or a few feet. In cities and suburbs it may be incorporated in  or next to the curb or sidewalk.
Another type of marker sometimes seen is a "PK" nail or more generically a surveyors nail - but the ones I've met normally do have "PK" inside a rectangle on the head - this it usually driven into a hole in a rock, though in more unfortunate cases it may have been driven into a tree (those often turn out to be troublesomely impermanent.)

If the line is murky, you may need to hire (usually you can split the cost with your neighbor if the line is actually unclear) a licensed surveyor. Try to make sure that at the end of that you have clear markers so you don't have to do it over.
If you are not in dispute or otherwise actively hostile with your neighbors, it's often a good idea to discuss the project with them anyway - and they may be aware of boundary markers that you are not, if they exist but are not obvious. If you both agree on where the boundary is you generally don't really need a surveyor, but a surveyor will help to make sure that everything is on the up and up if there is any room for dispute.
One final suggestion (even though you are putting in a fence) - plant something that lasts a long time (in the Northeastern USA, plain yellow daffodils are a good choice) near each boundary marker and/or along the line. They'll give you a clue every spring as to where the corners (and lines if you plant along them) are. This is a whole lot easier to spot than a rusty iron pipe in brown leaves. A fresh coat of paint on the markers themselves every couple of years can also be helpful.
Comment: Even if you're on very good terms with your neighbor now, you still should get the property line properly determined if they're not able to point you to the markers.  A fence that straddles the property line is a ticking timebomb that can detonate at any point in the future; most commonly when you and your neighbor have a falling out or one of your homes goes up for sale.
Answer: Your town/city/county should have that information on file, as it's likely that a survey was required for the sale of the property.  Depending on where you are, you might have gotten a copy of the survey when you bought the property.
Comment: The survey is only of use in this case if you can tie it into the physical corners. Everything in the survey is normally also in the deed - the process of surveying is largely that of connecting the deed description to the dirt (and the finer/more subtle points, at least out east where the original property description might be a tad vague or inaccurate by current standards) have to do with resolving "as described" and reality.
Comment: @Ecnerwal The survey should tell you exactly where to look for the irons (or at least one iron), which mark the property.
Comment: Which may be several houses away from yours.


Sitecore Powershell script for moving bunch of fields to template section

Question: We are trying to refactor few of the Sitecore templates. We need some help with powershell script. Is there any way to pull bunch of fields (around 70-80) to different template sections.
Manual pull is taking lots of time. Can we do this through powershell?
Answer: Let's say you start with a template like the following:

Then the following script will move items to a newly created section like this:

Using this sample, you can build in whatever logic you want. Keep in mind that if you are wanting to move fields between templates then you need to change the inheritance first.
<code># Get the template I want to change
$templateId = "{F8BC7158-5A2F-40FE-A7D9-453229EC325E}"
$selectedTemplate = Get-Item -Path "master:" -ID $templateId

$currentChildren = $selectedTemplate.Children
$count = $currentChildren.Count + 1

# Add a new template section
$templateSectionId = "{E269FBB5-3750-427A-9149-7AA950B49301}"
$newSection = New-Item -Parent $selectedTemplate -Name "Section$($count)" -ItemType $templateSectionId

# Move fields
foreach($currentChild in $currentChildren) {
    $child = $currentChild.Children[0] | Initialize-Item
    Write-Host "Moving $($child.ItemPath)"
    Move-Item -Path $child.ItemPath -Destination $newSection.ItemPath
}
</code>


Is there a way to show the total number of individual messages sent in a Google Hangout?

Question: I use Google Hangouts quite a ridiculous amount and I'd like to know if there's a way to show how many individual messages are sent between users in a Hangout conversation.  Is this at all possible?  If so, how can I do it?
Answer: I think that at this time is not possible to get a reliable number of posts sent as Google didn't make available as:

the Hangouts web UI doesn't have a messages counter.
the Google+ Hangouts API is intended to be used to develop apps to be used with video calls and it doesn't have a class for messages.
the Hangouts web UI only loads the most recent messages.
messages could be deleted
messages could not be recorded if the history is disabled.
Answer: There isn't an easy way to count the individual chat messages are sent, unless you want to go through your history and manually count, which is cumbersome.
The closest solution I know if is to view your chat history in your Google Account Dashboard: https://www.google.com/settings/dashboard
The "Gmail" section of this dashboard will provide a summary of all of your Gmail activity, including your chat history.
The chat history summary number is how many chat conversations you've had. I'm not sure how they calculate separate chat sessions between the same two people over time, but it'll give you a rough snapshot.


How can I prevent the backup camera from turning off in a Volkswagen Passat 2014 when going backward at over ~30 km/h?

Question: When using a Volkswagen Passat 2014 and going backward, I notice that the backup camera turn off when I start gaining speed (over > ~30 km/h). How can I prevent the backup camera from turning off?
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/133174/discussion-on-question-by-franck-dernoncourt-how-can-i-prevent-the-backup-camera).
Comment: You could always install an aftermarket head unit and (probably) an aftermarket reversing camera. If you're seriously getting into the sport of reverse racing, you'll need a gearbox mod as well. Have fun...
Answer: It's set in the ECU in the "Park/Steer Assist" module and controlled by an adaption channel called "Switch-off speed for parking assist" IIRC and you can change the value there (ironically jwh20 was correct in their initial guess - it's usually 15kph from the factory), the value has both lower and upper bounds that you can't go beyond (5kph -> 20kph).
This isn't something you can access through a menu in the car itself - if you want to change it you need something like VCDS, OBDeleven or Carista.
I seriously doubt those upper and lower bounds can be changed without some seriously major effort changing the firmware - and while 20kph might not sound like much, but firstly driving in reverse at speed is a bad idea in general, and trying to do it from a reversing camera view in lieu of a actually looking behind you is heading towards just plain dangerous.
Comment: @davidbak - er, movies aren't real life?
Comment: @davidbak part of the reason you see high-speed reversing sequences in movies is because the difficulty and associated risk/danger makes for dramatic viewing. Additionally many of the purported speeds you see them hit in the movies aren't even possible in an unmodified road car - reverse typically has similar gearing to first so you'll top out at around 30mph
Comment: I see people backing up at _very_ high speed all the time.  Yes, they're in movies, but, so?
Comment: obviously i understand about movies, thank you, maybe I should have added ;) to make my meaning clear
Answer: I want to offer more on the frame challenge, that you just shouldn't.
What you are doing is bypassing a convenience feature that refuses to support you being more unsafe.
Start by considering what a reversing camera can't do for you. It can't give full context. You only see what a small fisheye camera (usually low down on the rear) sees - and that is not enough for safety.
For example, cams are optimised for slowish reversing, so they are fisheye/distorted. They are usually low down, and miss or de-emphasise entire risk areas at the flanks and sides. More than a short distance they distort and de-emphasise rear objects too.  They miss overhanging objects (that stick out higher up perhaps). They don't show more distant objects in perspective. In fact they can't show you what's going on more than immediately behind. They mislead as to distance. They don't show lateral risks,such as dangers arriving from the sides, including for example people running from the side to go behind you.
Also these sound like places other people can go. Where wider awareness really matters at times. Driving is about risk reduction not just speed. You only need to hit one person, once, in 60 years.
Looking at a rear cam is one part of a picture. Its not all - and at any speed you're discussing, its far from enough to ensure safety.
Which brings up the other, more serious question.....
You can't reverse at speed unless reversing for some distance, and you describe the context as "large areas". Sounds like people aren't excluded from these "large areas".
If looking over your shoulder or keeping an eye on your main and side mirrors is difficult or inconvenient for a sizeable reversing manoeuvre, enough that you'd rather forcibly bypass a safety limit on the comparatively poor, limited and unsafe-at-speed rear camera, then you need to ask yourself if you are actually able to drive safely full stop, let alone at speed.
Update:
You added in a comment above, that "higher objects CAN be seen in the rear view mirror - the trunk doesn't block them.  You can face forward and see BOTH the camera view and the rear view mirror, at least in my car."
Your argument here seems to be completely untenable in a safety context.

Either:You are adamant that you indeed watch your rear view mirror anyway, at the same time, to watch for higher objects and things that are out of view of the parking cam but in view of the mirror, so these aren't a problemThen logically you don't need the rear cam to work at speed. After all the only time you want it for reversing at speed, is a time when anything relevant visible via parking cam is as easily or more easily seen in the mirror you say you would be using to address this risk. Because it seems, your main wish in this question is to use the parking cam to avoid a wall, or other large features behind you, and all such features would be much more visible in the mirror you are also looking at, as well.
Or:In any other case, my point about having sight of your context stands.
Comment: Frame challenges occur when the core of the question itself is misplaced/misdirected somehow - and especially if it's for safety reasons. What's important is that the issue may objectively be an issue in the real world, not just something like say, "you'll go to hell in the afterlife" for example. It's only "opinion" in the sense that, say, "driving on bald tyres is unsafe" is opinion. Meaning, modding your car to facilitate high speed reversing in what sounds like it could be public spaces, relying on the built in parking cam for safety vision, should not need a PhD to know needs challenging.
Comment: Not downvoting, but this is entirely opinion and does not address the question in any way?
Answer: At the risk of getting downvotes for answering a slightly different question from what is asked, (putting aside the other not-quite-answers of "don't drive so fast" and "don't drive in reverse"), the simplest method of having a camera feed while driving your car at high speed in reverse is probably to simply buy your own camera. You probably won't be able to have it display in the built-in console, but you would be free to have it always active, with whatever field of view you choose (and you can install multiple ones for a range of views).  You would even be able to see behind you when not in reverse, so this might be a useful alternative/supplement to the rearview mirror during normal driving.
Comment: At a guess, over your shoulders and also, all mirrors. To be aware of views that show the wider flanks and context, not just the low down fisheye view of a parking cam. If you can't, then you need to ask yourself if you can drive safely full stop, let alone at speed. I may add more in an answer.
Comment: @FranckDernoncourt If you're driving at speed in reverse while looking at a camera, safety is clearly not a major consideration for you.
Comment: Thanks, that'd work too, and it would be a good opportunity to improve upon the built-in camera's mediocre quality, which would increase the safety.
Comment: @Sneftel what do you want me to look at?
Comment: @FranckDernoncourt My wild guess is, that Sneftel - and I and a lot of others - want you to not treat your car as a toy. And not going full-speed in reverse whatsoever, camera or not.
Your camera will not show you anything when going above 30 mph in reverse. Don't think of this as a fault or malfunction, think of it as something that should never happen, and that is why the equipment stop working.
It's not the equipment that is failing, it's the driver.
Answer: Your root problem is a cognitive bias.
It's really difficult to understand "safety" when accidents happen rarely.
All minds are hardwired to learn about things by direct experience.  So when something happens to you, it burns in, and you never forget it.  Your mind does that automagically; even animal minds do it.  The "lizard brain" as it were.
But auto accidents of a particular kind don't happen often enough for you to directly experience the consequences of mistakes.
What distinguishes humans from animals is the ability to understand risk in an abstract manner - e.g. from an NTSB safety report...  From the advice of others... When the safety lesson contradicts your desires.
That is the problem.  Direct experience is the only compulsory teacher.  It is impossible to learn anything in the abstract unless you want to learn. Denial prevents learning.
Consider how you have reacted to the cautionary answers here.  This is the "recipe for disaster": rejecting abstract safety information merely because it is inconvenient.
This doesn't mean "do not do things", it means "find the safe way to do things".  I'm A-OK with high speed reversing.
You need your peripheral vision to back up safely
Because the most important information about unexpected traffic comes from beyond the fairly narrow wedge of a camera.
And the most concerning "traffic" is actually pedestrians, bicycles, skateboards, that kind of person. A person who has absolute right-of-way over you, in most cases - which means there is simply no way to escape liability for a collision.
Having to tell a court "I was nose-down in instruments, and not looking" will only be an enhancer for civil and criminal liability.
That means your head needs to be turned around full 180 degrees, shoulder twisted way over - yeah, I know the position.  I once occasionally drove a railroad inspection truck. Try reversing at 60 kph for a half hour. Oh yeah, you get stiff!  You won't hit any trains if everyone does their job, but hitting trespassers in an inspection car is not OK, and other inspection or MoW units may be sharing your track window.
All such movement is done on the simple rule: Be prepared to stop short of half the distance you can see.  If the other person is doing the same thing, an accident is impossible.  That is my axiom when driving a car, and that changes driving in surprising ways. Peripheral vision is essential to it, due to the X-factor of walkers, skateboarders, bicyclists and the like.
Answer: I'm sure it's tied in with the speedo signal from the transmission.
Being a relatively recent model I think you'll find that the display is controlled by the ECU which determines that the car is in REVERSE and is going < 30 kph.  These messages are passed between the ECU and the display via the CANBUS.
To override this (safety concerns aside - let's assume you know what you're doing) you will need to do one of two things:

Intercept the CANBUS signal between the ECU and the display module and re-write the signal that says TURN-ON or TURN-OFF so that it's on when you want it and off when you don't want it.  This is going to be somewhat technical so depending on your skills it may not be practical.

Intercept the speedo signal from the transmission and "fix" is so that it returns 0 when the transmission is in "R".  This will take a bit of engineering as well but probably less complicated.  The speedo output from the transmission should be fairly easy to find and a parts diagram of your transmission will likely show it as a replacement part.  You could then find some "R" signal, perhaps from the shifting mechanism.  Often there will be LEDs that light up or a switch signal that says "R".

Yes, both of these are somewhat technical but the folks at VW surely didn't consider your use-case when designing this system.  In fact it's clear they intended the display to be OFF when going > 30 kph in "R".
Comment: My bad, I see now that the OP said 30.  I'll update my answer.  Thanks!
Comment: Thanks for the clear answer! How did you find that the threshold was 15kph?
Comment: Got it, thanks, 30kph was an estimate, I don't know the exact value. I thought you were looking at the car's code directly :)
Comment: I don't have access to that, sorry.
Comment: Notwithstanding the insanity of driving more than 30 km/h in reverse except in a controlled stunt environment, would a car with either of those modifications be legal to drive?


Thermochemistry: What is the difference between the calculation of bond enthalpy and Hess's Law

Question: I know that Hess's law is an indirect way to find the heat of reaction using the known heat of reaction of 2+ thermochemical equations, thus the formula is delta heat of reaction = enthalpy of formation (product)- enthalpy of formation(reactant). But then, bond enthalpy also finds the change in heat of reaction with the formula: change in heat of reaction = bonds broken (reactant) – bonds formed (product). If it's negative, it's exothermic, and if positive, it's endothermic.
I am confused at the relationship between these 2 concepts since they are rather opposing each other.
Answer: You are confused as to why we take "reactants minus products" when calculating the enthalpy of reaction based on bond enthalpies.
Consider as reference state all your reactants and products in their atomic states, that is, with all bonds broken. Forming a bond releases energy, so the reactants and products all have a negative enthalpy $$\Delta H = -\sum\Delta H_\text{bonds}$$ with respect to this reference state. The enthalpy of reaction remains $$\begin{align*}\Delta H_\text{rxn}&=\Delta H_\text{prod}-\Delta H_\text{reac}\\ &= -\sum\Delta H_\text{bonds,prod}-\left(-\sum\Delta H_\text{bonds,reac}\right)\\ &= \sum\Delta H_\text{bonds,reac}-\sum\Delta H_\text{bonds,prod},\end{align*}$$
so the inconsistency you've pointed out is just the neglect of a minus sign.
Answer: ΔH of a reaction in terms of bond enthalpies = Σ bond enthalpies (products) - Σ bond enthalpies (reactants).
Therefore if the products are at a lower energy than the reactants, the reaction would be exothermic therefore ΔH would be negative.


Does Keynesianism increase the incentive to invest?

Question: Lets say you invest $1billion in a city in recession. The investment will have a multiplier, boosting the value of your investment. Thus if keynesianism was correct there would be an increased incentive to invest during recessions
Comment: I'm voting to close this question as off-topic because this is someone who is interested in an argument, not an answer. My bet is that it's the same ignorant troll that has created fake account after fake account.
Comment: Your question includes a flawed assumption: why would you assume that you'd recapture any significant portion of the additional output Because math. Have fun refuting keynesianism
Answer: Yes, the big success of Keynesianism was uncovering that there is an incentive to invest in a demand-led recession, from the perspective of the whole economy, because of the multiplier.
Just as you say.
However, there is no incentive to invest for individual profit-maximising firms, for exactly the reason dismalscience gives: the investment stimulates general demand; but (in general) very little demand of that newly-stimulated demand is for the particular good or service being invested in.
It is this gap between the sum of preferences of all maximisers of individual utility, and the preferences of the sum of all of those actors, that Keynesian investment fills.
Answer: Your question includes a flawed assumption: why would you assume that you'd recapture any significant portion of the additional output? Let's say that the multiplier is .05, so that for your billion dollar investment (let's say the you build a new factory), others in the city increase their total spending by \$50 million. What fraction of that \$50 million do you suppose would be spent on the products produced by your billion-dollar factory?
If you're being even halfway realistic, you should assume it's 1% or less— so maybe you'd net an additional half-million dollars on an investment you made in a factory that you built for a billion dollars during a recession... when people are generally purchasing less than usual.
Suffice it to say, Keynesianism does not imply that this would be a good investment decision.


How do I remove an image completely from a posted question?

Question: I have posted a question "How do I use serialEvent() in a Processing language program?" and originally included an image, not realising immediately that it contains the precise GPS co-ordinates of my house. I remove the image by editing, but, of course it is still there for anyone to see who examines the editing. Please, as a matter of urgency, can the image be completely removed?, or the co-ordinates blocked out?
Comment: Whatever you do, *don't* post a question on Meta so that everyone who sees it will find your house ..... oh, too late ....
Comment: Folishly I panicked
Comment: It's not so bad, I've seen someone posted his username and password into a question and edit to remove it then...okay let's all panic.
Answer: Simply delete the image and flag the post for moderator attention. We can now redact revisions without bothering the community managers, so this will get processed as soon as a moderator sees the flag. A second moderator has to approve the redaction (to guard against mistakes being made), but the process is usually fairly quick.
Either use the Contact Us form to speak directly to the community managers or flag the post for moderator attention using the "other" option explaining that you'd like the old revisions of the post expunged from the database. In the latter case all we can do is pass the request along to the community managers - as they're the only ones who can do this.
In the meantime if you're really worried about people seeing the history delete the post and we'll restore it once the revisions have gone.
As to removing the image - I don't know if you can do that. You'd have to contact the team via the "contact us" form and ask them if they can remove the image. Include the url of the image on imgur so they know which one you want deleting.
Comment: where do I get updates about the question I flagged? I had flagged a question, and nothing seemed to change.
Answer: Use the "contact us" link in the footer to write to SE and ask them to remove the information. They are the only ones with the ability to do that.
You could also flag the post, but then a moderator would simply forward that request to an SE employee anyway.


Handle cutouts safely using a router

Question: I'm new to using a router and have been experimenting with basic cuts on a table. I have not tried a handheld or freehanded on the table. I recently did all the cuts to make a serving tray and I want to cut out the handles. My plan was to cut two holes with a forstner, jigsaw between the two and then clean it up with a router. What is the safest way to go about this? Table or Handheld? Bit type, size and technique?
Comment: As before drill out the ends it makes it easier, use a guide bushing and a template with a large surface to stabilize the router making srure to secure the router
Answer: There are many ways to do this, any of which can be made safe enough for the risk to be acceptable.  I'll outline how I would do it, but there are probably a dozen slightly different variants that would also work just fine.
I would use a template bushing on a plunge router with an oversized template to make the opening.
Start by determining the radius on the corners.  To my eye this looks like about 1/4", so use a 1/2" (diameter) bit.  Find a template bushing that is big enough to fit the bit inside and attach to your router's base plate (making sure it's centered properly - your bushing set should include centering mandrels that fit in your router's collet.)
Next you'll make a jig with a hole in it.  The jig's hole should be oversized in both directions by the difference between the diameter of the bushing and the diameter of the bit.  I'd make this template by ripping two strips of scrap to the height of the hole plus the offset, squaring the ends, and gluing them between two more longer strips of the same scrap.  Marking out the center points of the hole before you glue it up might be helpful in alignment later.
The jig can be attached to the work piece either by clamping or with double-sided tape.  If you plan on clamping try to make the jig big enough for the clamps to be outside of your router's base plate.  It's no fun having to stop to move clamps around.
If you don't have a plunge-able bit you will have to start with a pilot hole.  You might also want to hog out most of the waste to save wear on your router bit and make the cut a little safer and less tear-out prone.  If your work piece is thicker than 1/2" you'll want to make the cut in stages.  This will be a through-cut so make sure you're working on a sacrificial surface (and you don't plunge through it!)
Place the bushing against the inside surface of the jig, turn it on, and plunge the router into the work piece.  Move the router around the jig in a clockwise direction.  The router should be moved fast enough to avoid burning but not so fast that the motor bogs down or you feel like you're "forcing" the tool.
Remove the jig and run a bearing-guided roundover bit around both sides (again in a clockwise direction.)
Comment: If you want to include a diagram for safe feed direction here's one clear one, [linkee](https://i.pinimg.com/originals/3a/4a/11/3a4a113833f3bc8913f1bb30800202f6.jpg) (don't know the original source).
Comment: Yeah, definitely you do not want to risk climb cutting unless you really know what you are doing.
Answer: Routing an inside feature like this is going to be awkward on a table. I'd clamp this up with a jig and use the router by hand to shape it.
Alternatively, if you are already hogging most of the waste out with other tools anyway, you could shape it with a rasp.

Handle cutouts safely using a router


How to UV map low res textures.

Question: So what I want to know is how to UV map low resolution textures. When I was exporting my UV layout it said the size of the UV layout was going to be 1024x1024 but I need the textures on my model to be 64x64. I was wondering if I put my 64x64 textures inside this 1024x1024 UV map in an external image editor then re-imported that UV map with my textures, would that keep my textures 64x64? I doubted that so that's why I'm here asking how to UV map low res textures. I'm new to using blender so sorry if this is a really nooby question.
Answer: I think what Duarte was trying to say is that the resolution of the textures doesn't matter for the UV layout. UV coordinates are bound to the mesh, not to the texture.
You can create a 1024x1024 texture in blender, then resize it in whatever image manipulation software you use. For example I tend to create quite hi-res textures (4k and above) in blender, baking them and later resizing them in gimp to whatever size the final result should have. The only problem is that you are losing detail on your texture map, the UV layout fits perfectly, though.
Comment: Ok so, if I export the UV layout and then in an external image editing program I move my 64x64 textures to fit inside the uv layout image, the textures will still be 64x64? So when I export the UV layout, all it really is, is a reference for me when I'm in a image editor? Of course, I delete the reference uv layout after I'm done positioning my textures so they fit inside the UV layout.
Comment: Just scale down the 1024x1024 texture to 64x64. No scaling, no moving around.
Comment: The textures I'm using are already 64x64, i placed the 64x64 textures on top of the 1024x1024 uv map. If i were to scale down the 1024x1024 uv map with my 64x64 textures on it  they would be way to blurry afterward. Sorry if this is getting annoying.
Comment: Maybe you could post a screenshot? 64x64 is quite a small size for textures. Since this size doesn't contain much pixels the result will be blurry and it has nothing to do with the UV layout.

A diffuse texture is a digital image, nothing more. If you would downscale a photo (reduce its size from 4k to 128X64 pixels) it would also be blurred if you try to upscale it again.
Comment: http://imgur.com/8jYP6Qq
Comment: What I need is the textures inside the UV map to stay 64x64, now I know they will stay 64x64 but if I use the uv map for a reference and then save that file the textures will be saved in a 1024x1024 image and I can't have that. So should I upscale the 64x64 textures to 1024x1024 then apply those textures to the 1024x1024 uv map then down scale the entire UV map 10 64x64
Comment: also do you know how to export an obj file from blender with your textures on it?
Comment: One again: You don't "scale" uv maps, you scale texture images. UVs are bound to the mesh.

Create the 1024X1024 texture in blender, open it in gimp or whatever you use, scale it down to 64x64.

If you hand-paint it. I'd suggest you wait with the downscale until you're done with painting. If you want to bake something in blender, bake it to 1024x1024 then scale it down.

Sry, I really don't get the problem with it....
Answer: From my limited experience with UV unwrapping exported UV layouts are purely for reference purposes while creating your texture, you don't "re-import" them to Blender.
Texture coordinates (or the UV layout) is stored inside Blender on the mesh itself, the 1024x1024 image you export is used only for knowing what goes where while creating/painting your texture in whatever graphics editing program you want to use.
You can directly create a new image with whatever resolution you need (higher or lower) and use it as texture inside Blender without worrying about image size.
UV coordinates automatically adjust to whatever image size you choose, you only have to be careful to keep the same image aspect ratio so that your texture wont be stretched. As long as you maintain the same width and height proportion it should be fine.
Just  create a new 64x64 image, paint your texture vaguely respecting the exported UV layout (you can overlay it for reference) so that it matches the correct parts of the mesh.

How to UV map low res textures.


Is there parking near Kirby Cove, San Francisco, USA?

Question: I would like to get a nice view of the Golden Gate Bridge from Kirby Cove. I am wondering though if there is any sort of parking area near Kirby Cove. I am also wondering if it is jam packed for parking in July.
Answer: There's a fairly small amount of parking in two clusters along Conzelman Road near the visa point. From there you can hike down the trail all the way to Kirby Cove (be advised, especially for the way back up, that it's a fairly steep trail).
It may be somewhat rather, but some people only stop to take a few pictures, so if the spaces are full, you could wait a bit and take the space of someone leaving. Failing that, there's a bigger lot just after the underpass and you could walk from there. There is also more parking further down Conzelman Road, such as at the traffic circle or Hawk Hill. Visiting outside of peak visiting periods, especially weekends during the summer, may help avoid crowds and traffic.
Once you're done there, I'd also recommend going a bit further and checking out the lighthouse at lovely Point Bonita. Parking right near the trail to the lighthouse is very limited, but there are other spots in the area.
Comment: Too add to this. I ended up going there in July on a Saturday, and it was an overloaded zoo. It was very hard to find parking remotely close, and the roads were bumper to bumper, and the sidewalks butt to butt.
Comment: Thanks for the update @ScottF. A weekend during high tourist season does indeed sound like a busy time.
Answer: Disclaimer: I've only done this by bike. I've rented a bike a few times in San Francisco, crossed the bridge and rode up the hill. There are two main parking areas (I believe!) and in the times I've been it would seem likely that you'd be able to park, perhaps if you have to wait a bit for someone to leave after doing a bit of sightseeing. Also, you can park in places on the road up the hill but you might have to walk a bit.
You do get a nice view of the bridge from the top of the hill providing the fog hasn't descended.

Official information including a view you might see:

Some information also available on a tripadvisor thread.
Comment: +1 Important point about the fog. If you're interested in views, try to plan your visit around the fog. The [forecast map](http://weather.sfgate.com/auto/sfgate/geo/fogmap/index.html?query=fogmap) is at least marginally useful, but as a general rule during summer, if you head out there as the morning fog burns off (if the morning fog every burns off), you'll get at least some time before it comes back in the afternoon or evening. Or stick around and the views might be more interesting as the fog comes in (or you might see nothing).


Clustering large scale data in fine-grained clusters

Question: I've got large amount of data (e.g. 100K) and I want to cluster them in very fine-grained clusters (e.g. 10K). I look for an appropriate algorithm that uses the similarity function instead of whole data and also I can't compute whole similarity matrix because of data scale. Python implementation is appreciated.
Answer: You are facing some scalabiliy issues here. Most clustering algorithms run in $O(n^2)$ or worse (most hierarchical clustering are implemented in $O(n^3)$); many even have an $O(n^2)$ memory requirement.
The only algorithms with a better runtime that right now come into my mind are DBSCAN and OPTICS: with an appropriate index structure these can run in $O(n \log n)$ and only need linear memory. However, if you do not have an appropriate index they also will be in quadratic runtime. And I don't know if there is a good index structure for textual similarity. Furthermore, you cannot specify the number of clusters you want to get out. They are meant to find structure in the data, not just partition it "somehow". They also will produce noise points they do not consider to be part of any cluster.
And of course there is k-means. It's runtime is linear in n: $O(n*k*i)$. But since you plan to use a very high value of k, and in particular i*k>n will likely hold, you are essentially quadratic, too.
Furthermore, as you are working with sparse data, you will need a variation of k-means known as "spherical k-means". And even then, there is quite some doubt whether or not the results of k-means are very meaningful. The problem is that the means will no longer be sparse. They are not real "text" either, obviously. So to some extend they are quite anomalous. So in my opinion, k-means is quite okay if you just need to partition your data set somehow, but I do not consider this to be cluster analysis. It will no longer partition the data according to some inherent structure of the data that the algorithm identified. Instead, it just tries to optimize the mathematical criterion of the sum-of-squared-deviations, which often has an unclear relationship to whatever "structure" there is in the data.
As for performance: there are a number of ways to speed up k-means, but very few implementations support anything but the most basic Lloyd algorithm. For example, you can put your means into a index structure to get the cost of an iteration to $O(n \log k)$, which does make a difference for large $k$. However, again, this will likely not work with textual similarity. Then there is a variant that not only tracks the closest mean, but keeps the distances to all other means. By assuming triangular inequality, it can avoid recomputing distances by tracking if any mean moved enough to become the new closest mean. This will effectively bring down the factor $n$, but comes at $O(n*k)$ memory cost. And your similarity function probably will not satisfy the triangular inequality...
But the main problems is that we don't know what your goal is. If we had more information of what you are trying to do with the clusters, we might be able to point you at some more appropriate method. I hope that I indicated enought that while k-means will produce a clustering of the desired number of clusters, you actually do not have any guarantee that it is much better than splitting the data into random cells. Largely, because you would need a definition of "better" to be able to get a better result.
Comment: Thanks, I should be more clear about my goal. By clustering I want to do some kind of Co-reference resolution in text. That means as you said my similarity function doesn't guaranteed to be triangular. Specifying number of clusters isn't my preference but the gold clustering that I'm looking for should results fine-grained clusters. How can I use appropriate indexing for DBSCAN or OPTICS methods? I tried using *scikit-learn* implementation of DBSCAN, but It computes whole similarity matrix that I don't want.
Comment: You should try the DBSCAN implementation of ELKI. There is a Tutorial on adding a custom disance function: http://elki.dbs.ifi.lmu.de/wiki/Tutorial/DistanceFunctions
Indexing for distance functions with unknown properties is hard. Are you using cosine, or something more complicated? ELKI does have support for Cosine in R-tree indexes, but the acceleration may not be that good, because MBRs and Angles are too different concepts. Use STR bulk load.
Answer: I've had some success with using standard algorithms (e.g., k-means, etc.) and sparce matrices...are you familiar with those? There's a related StackOverflow question you may find helpful, but, basically, a sparse matrix is a compact way of representing a large matrix that is primarily zeros. Using these as a data type tends to help, as they bring a substantial memory reduction over using the full matrix. I know you asked about Python, but there are also some great resources for creating/working with these data types in R (e.g., the SparseM package).
Comment: My data is not matrix inherently, records are pieces of text and I can compute their similarity. Also I can't represent them with term-frequency vector in sparse matrix, because my similarity function completely differs from cosine or any other vector space model idea.
Comment: @nournia Okay, does your similarity function output a number? Do the numbers obey the triangle inequality?
Comment: I don't know, it may or may not support that criteria.


Testnet eWallet?

Question: Is there any eWallet available that works on the TestNet? I want to test some payments and so forth and sometimes I want to have an access to an online wallet, so I don't need to hassle with installing Bitcoin on various machines.
Answer: I have recently created a Faucet and an eWallet for the TestNet. It is very basic, but serves its purpose.
Comment: Unfortunately, every time I try to create a TestNet wallet there and then request a tiny amount to it (0.27 BTC looks like at last load), I get an error that reads: "We are sorry, but an error has occurred.

API error 5 (urlfetch: DEADLINE_EXCEEDED)

Back to main page.

Server code created by ThePiachu."
Comment: OK, seems to be working now. I tweeted @ThePiachu so maybe he fixed! One thing I noticed was that when the CAPTCHA was just the simple numbers on the side of a house (i.e., to use humans to improve Google Maps), the request did not work. However, once they were actual letters/words, they did. Could be entirely coincidental ..
Answer: I built a dedicated testnet wallet during a weekend hackathon
http://testnetwallet.com
Answer: Andreas Schildbach's Bitcoin Wallet for Android comes in a second variant that uses testnet, so you can have it on your phone or tablet with no hassle.

Testnet eWallet?


Submit a New Copy of List Item

Question: I have a SharePoint List that has an InfoPath Form template. I am encountering problem, I have a List Item and when Item is Approved I want to make a copy of it. What I did was when item is approved, a DCR button is visible and it allows the user to edit the document and make some changes. what I want is when the user hits the save button it creates a new item on the List, unfortunately, it just overwrites the list Item that I made and it does not create new List Item.
Answer: This is available when using a FORM LIBRARY (I'm currently trying to find a way with LIST ITEMS, but it doesnt look possible). On the Submit Data Connection you specify the Form name. Simply set the Form Name to a field on your form, and update that field to something else before submitting via the Data Connection. You now have two forms in your library, the original and and new one based on the original, all done from an InfoPath Form, rather than SharePoint Workflow.
Answer: You talk about a list and an InfoPath form. Is this a list form? Or is this a document library, since you mention a document? Or is this an InfoPath forms library? Please provide these details.
In any case, if you want to duplicate an item, you won't be able to do that from within the current item.
You can easily create a workflow with SharePoint Designer that creates a copy of the item if it is approved.
Comment: I am working with a Sharepoint List @teylyn.. Im sorry for the "document" term. As much as possible, I want to make use of the Infopath form to make a new List item with the values and submit it to List without overwriting the previous List Item. Hope you could help.
Comment: That cannot be done with a list form. You will need a workflow that starts when an item is changed. If the approval field = "Approved" create a new item in the list and populate it with the current item field values.
Comment: I see @teylyn. So I guess, I should make use of Library instead of a List for me to achieve this. Thanks for the help.
Comment: No, a library won't make a difference. Please read my comments again. Use a WORKFLOW in Sharepoint Designer to duplicate the item. You CAN duplicate a list item. But you CANNOT do that from WITHIN the list form. YOU NEED A WORKFLOW to duplicate the item.

Submit a New Copy of List Item


Does a pair of disjoint homotopic cycles in the dual separate the graph?

Question: Let $G$ be a graph embedded on an orientable compact surface of genus $g$ so that the embedding is cellular. Consider the dual of the graph $G^*$. Let $C_1$ and $C_2$ be disjoint cycles in $G^*$ that are homotopic to each other and let $E_1$ and $E_2$ be their corresponding edge sets in $G$ respectively. Is $G \setminus (E_1 \cup E_2)$ a disconnected graph?
Answer: Yes.  Let me write $\Sigma$ for the surface on which $G$ and $G^*$ are embedded.
Because the cycles $C_1$ and $C_2$ are homotopic, they are also in the same $\mathbb{Z}_2$-homology class.  So by definition, the symmetric difference $C_1\oplus C_2$ is the boundary of the union of some subset of faces of $G^*$; call this union of faces $U$.  (In fact, either $U$ or its complement $\Sigma\setminus U$ must be an annulus, but this isn't important.)
Because $C_1$ and $C_2$ are disjoint, the symmetric difference $C_1\oplus C_2$ is equal to the union $C_1\cup C_2$.  In particular, we have $C_1\oplus C_2\ne \varnothing$, which implies that both $U$ and its complement $\Sigma\setminus U$ are non-empty.  In other words, the subsurface $\Sigma \setminus (C_1\cup C_2)$ is disconnected.
Any path in $G$ can be viewed as a path in $\Sigma$ that avoids the vertices of $G^*$, and vice versa (up to homotopy).  Thus, the (graph) components of $G\setminus (E_1\cup E_2)$ correspond bijectively to the (surface) components of $\Sigma \setminus (C_1\cup C_2)$.  We conclude that $G\setminus (E_1\cup E_2)$ is disconnected.
The assumption that $\Sigma$ is orientable is never used.
Comment: Sorry, no.  But the observation that two simple disjoint homotopic non-contractible cycles bound an annulus (which gets you most of the way there) appears in David B. A. Epstein. Curves on 2-manifolds and isotopies. _Acta Mathematica_ 115:83–107, 1966.
Comment: Jeff, can you point me to a reference which contains this result?