Installing anaconda to different folder from home on Linux

Question: I want to install Anaconda to a different path such as /opt on my linux server, but I keep getting ERROR: File or directory already exists: /opt, even though there's no files or directory in there. It won't let me install unless I install it in the home folder, any ideas why and how to resolve this problem?
Comment: I had the same problem, I think I was pushing the space bar at the end, or the folder really was already there and I had to delete it.
Answer: You need to give also the name of the folder that it will create, like:
/opt/anaconda3

anaconda3 folder doesn't exist yet, but the installer will create it.
Answer: At the time of installation of the anaconda it will ask for the path where anaconda to be installed as follows:
Do you accept the license terms? [yes|no]
Please answer 'yes' or 'no':'
>>> yes
Anaconda3 will now be installed into this location:
/root/anaconda3

  - Press ENTER to confirm the location
  - Press CTRL-C to abort the installation
  - Or specify a different location below

Here we press enter if you want to install it in root/. But if you want to install anaconda into another dir. you can specify the path and anconda3 as the dir name in it as follows:
[/root/anaconda3] >>>  /opt/anaconda3

press Enter. You will see the following as the output in the terminal:
PREFIX= /opt/anaconda3
installing: python-3.6.3-hc9025b9_1 ...

It means it started installing the anaconda on the specified path/dir i.e. in /opt/anaconda3. complete the installation.
Answer: wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh
Miniconda3-latest-Linux-x86_64.sh -b -p /opt/miniconda3


BB drop vs BB height from stability perspective

Question: While I have heard that a lower bottom bracket tends to give more stability, I'm confused as from which point of reference yields such an effect, from the wheel axle (BB drop) or from the tire contact patch (BB height)?
Comment: It is perhaps worth noting that what influences the stability is the height of the center of mass (and perhaps the longitudinal distance of the tire contact spots, and the fork angle, and the longitudinal position of the center of mass which we'll all ignore, i.e., hold constant here). The height of the center of mass depends not on the BB height but on the saddle and handlebar height. The BB position is only interesting because the lower it is, the lower the saddle can be (while maintaining a sound leg geometry).
Comment: Does center of gravity of the rider really play a role on a bicycle? A bicycle is pretty much an inverted pendulum. Not a box (or ≥3 wheeled vehicle) where the stability depends on the width vs. CoG height. In the direction of travel it does influence how easy you go over the bars of course.
Answer: The conventional wisdom is you get more stability the closer you can get the center of mass to the contact patch. There are many other factors that could play a role in this than just the ones related to BB height (such as cargo placement), but the reason BB height matters so much by this reasoning is that the rider's body will typically be in a fixed position relative to the BB center. In other words, the rider positioning/ergonomics are conceptualized as not being affected by the BB height, but they are offset up and down in space by it. Thus, the ground and the BB center are the reference points.
BB height and BB drop are numbers with different meanings and uses that are both used to work with this concept.
BB height is the measure of the ground to the BB center given a specific set of tires. Thus, a BB height number by itself tells you everything about the BB's relationship with the ground, but contains no information about the drop number or the inflated diameter of the tire. (If you had one of those numbers additionally, you know the other.)
BB drop is the measure of the BB center's vertical distance away from a line drawn between the axle centers with a given headset. Thus if you know it, you know what the BB height will be with a tire of any inflated diameter. (You could also take it a step further and add the effect of rim width to the inflated diameter.) With a drop number you can answer questions like what is the smallest tire you can run while maintaining a target minimum BB height or what is the largest you can run without surpassing a target maximum. Framebuilders concerned with getting to the lowest BB possible while avoiding pedal strike will decide on a drop based on a chosen crank length, whereas mass-produced frames tend to have conservatively high BBs (low drop) to minimize the risk of pedal strike with a variety of crank lengths.
BB drop is a more straightforward number for comparing the design intentions of different frames. Using BB height number for the same purpose requires stipulating what tire was used to get there, because BB height contains no information by itself about the tire diameter.
There is a deeper conversation regarding some of the assumptions made in the premise of "lower center of mass = more stability." One is when and whether the rider position actually should be conceptualized as immutable in relation to the BB center. On inclines, in order to maintain traction a rider may need to shift their mass relative to the ground, leaving behind the notion that their mass is fixed relative to the BB center were they on a different bike with a lower BB. In turn, between two different frame designs that chose different BB heights for ground clearance needs, the higher one could have longer chainstays to mitigate this effect in the climbing direction, further muddying the viability of simple comparisons that only look at BB height/drop as a factor. These considerations are likely to weigh more on frame designs for technical as opposed to high-mileage, load-carrying, or recreational/utilitarian riding.
Comment: To add to your last paragraph, this gets even more complicated with full suspension bikes that lower varying amounts based on the amount of sag the rider prefers
Answer: The dimension I always see on spec sheets is BB drop, which isn't dependent on tire size.
Greater BB drop = lower bottom bracket = more stability
Answer: As others have stated, both numbers express how low the rider's/bike's  center of gravity is, so they both relate to stability.
Bottom bracket height inherently will vary with tire size. To provide BB height, the geometry chart would have to specify some sort of reference tire. The problem is that nominal tire sizes still vary in width and diameter when mounted, i.e. a 25mm Conti GP 5000 and a 25mm Michelin Pro Cup probably have different diameters. Moreover, the tire's size and diameter will vary depending on the rim they're mounted to, with wider rims (I think) increasing the diameter.
Furthermore, all-road bikes or road-oriented gravel bikes can be designed to accept up to, say, 40mm tires, but they can still perform nicely with 28-32mm road tires mounted. This would cause a pretty big change in BB height. With older road frames that would typically come with 25mm tires, with clearance for 28mm, the BB height might not vary as much.
Answer: Bottom bracket drop is what frame makers specify since bottom bracket height depends on the tire size.
However, what you should be using is the bottom bracket height. That's the parameter you're interested in, it specifies cornering clearance and stability. However cornering clearance also depends on crank length.
Usually for good cornering clearance on 700c (622mm bead seat diameter) wheels, BB drop is about:
215 - crank length + tire width

So for example on my Surly Long Haul Trucker where I use 170mm cranks and 28mm tires:
215 - 170 + 28 = 73

However, the Surly LHT has 78mm BB drop, so one can see it doesn't have practically any cornering clearance even for the 170mm cranks. The reason is that I'm misusing it; as a touring bike it's intended for larger tires. Actually I think the tire size ideal is 35mm for a touring bike and it has been designed to be usable for 175mm cranks too. Let's recalculate:
215 - 175 + 35 = 75

So it has 3mm more bottom bracket drop than what good cornering clearance would need. That's because it's a touring bike. A general purpose road bike would remove 3mm from the BB drop of this frame (plus assume maybe 23-32mm tires instead of 35mm tires, meaning BB drop would need to be much smaller actually).
Comment: When you factor in the variability of pedal widths and thicknesses, I can help but think that the 73 mm vs 75 mm clearance are essentially the same.


Did Lahiri Mahasaya defeat Swami Dayanand Saraswati in a debate in Kashi?

Question: I heard recently from a friend that the famous yogi named Lahiri Mahasaya had once debated with Swami Dayanand Saraswati in Kashi and successfully defeated the founder of Arya Samaj (An organisation which strictly rejects the concepts of murti puja, avatars and bhakti as well as some scriptures such as Puranas and Agamas). However, my friend was unable to quote from any authentic sources. Can anyone tell me the details of this incident and the source of this story?
Comment: Yes that happened
Comment: isnt it opinion based
Comment: primarily opinion based...
Comment: There was a great difference between Rev.Yogiraj Lahiri Mahasaya and Maharishi Dayanand Saraswati in the latter being merely a scholar of Vedic texts and not a realize soul.We just can't begin to even compare the two.
Comment: opinion based and unwanted.Did Dayanandaji stop preaching after this? If not, whats the gurantee that this is true?
Comment: @Partha There's nothing opinion-based here. I'm not asking whether it is true or not. My question explicitly says "what is the source of this story?" However, personally I do believe in the story.
Comment: @SuryaKantaBoseChowdhury Actually many such stories are constructed in hagiographies and so cross-checking is needed
Comment: Can you give source where arya samaj reject  tantras
Answer: Arya Samaj accounts don't mention such a debate, but this excerpt from the Yogiraj Charit, a traditional biography of Lahiri Mahasaya, describes him defeating Dayananda Saraswati in a debate on idol worship, in the course of which he magically silences Dayananda Saraswati's supporters.

I would to narrate an incident from the life of Yogiraj Rev. Lahiri Babaji. Once Shri Dayanand, the founder of Arya Samaj visited Varanasi. He was totally against idol-worship and considered himself to be brahmagyani i.e the self realized. He announced in Kashi that idol-worship was useless and should be stopped immediately and that God could only be realized through Veda-recital. He also challenged the scholars of Kashi to participate in a religious debate on this. He proposed that if he won, all the idols from the different temples of Kashi would be consigned to the Ganges. Everybody knew Shri Dayanand and his logical viewpoints. So no body came forward. The news spread like a wild fire. When it reached the king of Kashi, Yogiraj Lahiri Babaji was teaching the prince (as a tutor) in the palace. On seeing the worried face of the king, the legendary Yogiraj said "Do not worry, everything will be all right". The next day Sri Dayanand and Rev. Yogiraj were face to face at Dashashvamegha Ghat of Kashi in order to discuss the religious
issues raised by Sri Dayanand. Sri Dayanand asked his question "Is God formless or has God a form?".
  Rev. Yogiraj in his usual composure said "God has many forms but at the same time God has no form". Hearing this, the disciples of Sri Dayanand started shouting and used objectionable words aimed at Yogiraj. Yogiraj requested Sri Dayanand to exercise control over his disciples but Dayanandji could not discipline the hooligans.
  Indeed they wanted Yogiraj to concede defeat and make a retreat. At last Rev. Yogiraj told Dayanandji "Since you could not make them quiet so now I am trying to make them quiet". Having uttered these words Rev. Yogiraj closed his eyes. All of a sudden there was complete silence. All the hooligans who were shouting found themselves helpless, their mouth remained open and the jaw-movements stopped. Sri Dayanand was taken aback.
  At this moment Rev. Yogiraj said "Water does no have a form of its own but when it is transformed into ice, it has a form". In the same way so long as we try to perceive God through our sense organs,
God has various forms but when we transcend our sense-organs we realize the truth (in that light of soul and self-awareness) God is formless.
  This God has various forms but at the same time God does not have a form i.e. God is formless". Everybody was satisfied with this irrefutable explanation emanating from a realized master. Sri Dayanand had nothing to ask after listening to such a speech loaded with nothing but truth.
  At last Sri Dayanand requested Rev. Yogiraj to bring his disciples back to normalcy. Then Yogiraj ordered one of Dayanand´s disciple to bring water (the Gangajal) offered on Kashi Viswanath Shivalinga. When the water was sprinkled on the faces
of those hooligans by Rev. Yogiraj they came back to normalcy. Sri Dayanand left Kashi immediately.

By the way, this isn't the only time Dayananda Saraswati lost a debate; he also lost one to a Sri Vaishnava at some point, as described here.
Comment: Is this verse authentic or interpolated? I have not found any other source regarding this. Obviously though, Arya Samajis won't want to accept this fact regardless of its historicity.
Comment: @sv. I added a source, an Arya Samaj book.  It doesn't mention the fact that Madhavacharya was a Sri Vaishnava though.
Comment: "By the way, this isn't the only time Dayananda Saraswati lost a debate; he also lost one to a Sri Vaishnava at some point." - this is an unsupported claim. Needs a citation banner.
Comment: I checked the reference you just added and now you are misquoting it. It says the opponents followers thought Dayananda Saraswati had no answer after waiting for 2 minutes and left. But he gave a written response later. How is that losing a debate?
Comment: @sv. It's how the format of the debate worked.  He was given an opportunity to make a response and he didn't make a response in time.
Comment: You know any book which critically analyses the differences between Arya Samaj translation and that of griffith or others and proving how Arya samaj is wrong?
Answer: First off all let me clarify that rishi dayanda was not only a great scholar of Vedas and Sanskrit but also a self realized soul just like lahari mahasya. The meeting of lahri mahasya with rishi is not documented in any of his biographies one of which was researched  by  a Bengali and non Arya samajis pandit Devendra mukhopadhyay. The first and most authentic biography of lahrimahasya is written by pramhansa yoganda also did not mention of this kind of any meeting. Lahri mahasya was not a scholar of Sanskrit so his question of teaching sons of Kashi naresh is doubtful.It is well known historical fact that wnen rishi challenged the pandits of Kashi shastrath took place between rishi and various pandits and lahri mahasya was not present in that. This debate was organised by Kashi naresh though he was highly biased towards idol worship.Debate was not completed and in between miscreants attacked rishi.His life was saved by kotwal raghunath Prasad who was working under British government.After this debate also rishi challenged the pandits several times but they never came forward.Kashi naresh once called rishi to his palace and apologize for the misbehaviour.It is true that lahrimahasya was a great Yogi and possed many siddhis but let us not forget that he was a grasthi and rishi was akhand bhramchari so siddhis of lahrimahasya could never harm swami ji.Lahri mahasy become popular in Kashi when he was introduced to people of Kashi by Tailanga swami.Similar kind of false story was also fabricated related to Tailanga swami .He wrote a letter to swami ji and he left Kashi immediately. The true fact is that swami ji visited Kashi several time and challenged the pandits and scholars several time to prove idol worship according to vedas in which they completely failed. Even if we consider Tailanga swami and lahari mahasya greater Yogi than rishi then also they could not defeat swami ji because his view was based on truth revaled in Vedas by omnipotent God.No Yogi can go beyond the truth that is fact.Next is the historical background in which it is said that swami ji had many followers in Kashi at that time is totally false because he had only two or three followers in Kashi at that time.Now it is said that lahrimahasya silenced his followers why not he silenced the rishi because he was the main person behind the opposition of idol worship.All these historical events totally fabricated recently because till date pandits of Kashi are not able to prove idol worship on the basis of vedas .Due to this reason these false historical events are fabricated in names of Yogi's and saints of Kashi.
Comment: you written good explanation.
Answer: No. I do not think such a thing ever happened.Because

The ONLY authentic and detailed biography of Sri Shyamacharan Lahiri (Puran-Purusha Yogiraj Shyamacharan Lahiri written by Ashole Kumar Chattopadhyay, published by Amita Chatterjee) forewarded by the grandson of Yogiraj( Satyacharan Lahiri) does not mention any such incident. On the otherhand, the name of Dayananda Saraswati has been mentioned alongwith Sri Chaitanya, Nanak and Kabir in the same biography as great saints (page 135). About Sant Kabir, Sri Shyamacharan Lahiri writes : Kabirji appeared as Satya Sukrita in Satya yuga, as Karunamaya in dvapara yuga, Munindra in Teta yuga and Kabir in the Kali yuga(Ibid. page 118).He also says that Kabir is One with Brahman.
As per the great scholar of bengal late Srijiv Nayatirtha,

Dayananda was defeated by late Taracharan Tarkaratna, the sabha-pandita of Kashiraja and father of late Pramathanath Tarkabhushana. According to 'Satajivani', Dayanandaji was defeated at a garden near the famous Durga temple of Kashi on 17 November 1860 (page 197).

Reference: 1.Puran-Putusha Yogiraj Shyamacharan Lahiri by Ashoke Kumar Chattopadhyay.

Omkarnath Rachanavali, Mahamilan Math, Vol. 7. page 25-26.


How to implement INotifyPropertyChanged

Question: I need help implementing INotifyPropertyChanged in my own data structure class.  This is for a class assignment, but implementing INotifyPropertyChanged is an addition that I am doing above and beyond what the rubric requires.
I have a class named 'BusinessRules' that uses a SortedDictionary to store objects of 'Employee' type.  I have a DataGridView showing all of my employees, and I want to use my BusinessRules class object as the DataSource for my DataGridView.  The BusinessRules container is required for the assignment.  I have tried to implement INotifyPropertyChanged in this class, with no success.
The DataSource that I have working is a BindingList.  Presently, I am using that BindingList as a 'sidecar' container and setting that as my DataSource.  Every change that I make to my BusinessRules class object is mirrored to my BindingList class object.  But this is obviously sloppy programming, and I want to do better.
I have tried to implement INotifyPropertyChanged in BusinessRules, but when I set my instantiated BusinessRules object as the DataSource, the DataGridView shows nothing.  What I suspect the problem to be is with the NotifyPropertyChanged() method.  I do not know what to pass to this, nor what to do with what is passed in.  Most examples deal with changing a name, but I am more concerned when a new object is added to the SortedDictionary.
    private void NotifyPropertyChanged( Employee emp )
    {
        PropertyChanged?.Invoke( this, new PropertyChangedEventArgs( emp.FirstName ) );
    }

What do I need to change in order to get this working?  Will you explain why my attempt is not working?
I am notoriously bad about forming my questions on StackOverflow.  This is not intentional.  Please, let me know what other information you require, and I will provide it as quickly as I can.
Here is a link to my BusinessRules source code.
Answer: It will be very helpful if you read tutorials on how to implement MVVM.
You'd wanna have a base class that implements INotifyPropertyChanged interface. So all your view models should inherit from this base class.
public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected void RaisePropertyChangedEvent(string propertyName)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

// This sample class DelegateCommand is used if you wanna bind an event action with your view model
public class DelegateCommand : ICommand
{
    private readonly Action _action;

    public DelegateCommand(Action action)
    {
        _action = action;
    }

    public void Execute(object parameter)
    {
        _action();
    }

    public bool CanExecute(object parameter)
    {
        return true;
    }

#pragma warning disable 67
    public event EventHandler CanExecuteChanged;
#pragma warning restore 67
}

Your view model should look like this.
public sealed class BusinessRules : ViewModelBase

Here's an example on how to utilize the RaisePropertyChangedEvent.
public sealed class Foo : ViewModelBase
{
    private Employee employee = new Employee();

    private string Name
    {
        get { return employee.Name; }
        set
        {
            employee.Name = value;
            RaisePropertyChangedEvent("Name");
            // This will let the View know that the Name property has updated
        }
    }

    // Add more properties

    // Bind the button Command event to NewName
    public ICommand NewName
    {
        get { return new DelegateCommand(ChangeName)}
    }

    private void ChangeName()
    {
        // do something
        this.Name = "NEW NAME";
        // The view will automatically update since the Name setter raises the property changed event
    }
}

I don't really know what you want to do so I'll leave my example like this. Better read different tutorials, the learning curve is a bit steep.

How to implement INotifyPropertyChanged


General questions of curiosity

Question: Would it be appropriate to post a message in stackoverflow asking about specific resources one might recommend for learning/tutorials or even game-related methods to learn a subject? (or, is that out of bounds or off-topic?)
Comment: No, that's not really suited to a Q&A site. From the help page: *"You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page."* How to learn something, or requesting resources wouldn't constitute a question about a problem that you face, it's a discussion / poll / resource request post, not an actual question.
Comment: Thank you for the response. I assumed this to be the case, but I thought I would throw it out there. Where might one go (similar to SO) to answer such questions? Any ideas?
Comment: Google for "X forum" where X is the topic you wish to ask about. Chances are you'll get a lot of hits regardless of the topic.
Answer: No. No. No.
Resource questions are entirely off-topic, not just on Stack Overflow, but essentially all of the network.
We call them shopping questions, see the Q&A is Hard, Let's Go Shopping! blog post about them.
Comment: Thank you for the blog post. I figured there must be something out there that particularly addresses this.

General questions of curiosity


GRUB doesn't load up

Question: http://paste2.org/nHkIgA56 <<< most recent (Look at this one)
I am currently running duel boot between Ubuntu 16.04.1 and windows 10 using GRUB.
One day I just booted up the BIOS and poked around but saved no changes, then the GRUB just stopped loading.
I ran boot-repair(recommended) on Ubuntu live-session for first time and fixed the issue
http://paste2.org/vMghmvC1 <<< successful first try (for reference, not important)
(1) GRUB loaded up when restarted (success)
(2) boot up Ubuntu with all my previous settings still there (success)
(3) restart comp from Ubuntu and GRUB loaded up (success)
(4) boot up Windows (success)
(5) restart comp from Win and GRUB loaded up (success)
(6) checkout BIOS and restart, GRUB didn't load and boot straight to Window (failed)
(7) restart comp windows boot up directly skipping GRUB (failed)
I tried adjusting boot order with no success and also tried replicating the previous boot-repair method on Ubuntu live-session with no progress.  Windows just boot up directly without GRUB displaying.
One thing I find odd in BIOS on HDD0 password is "frozen" as oppose to superviser and user password is "set" or "clear"??
Comment: Have you set a supervisory password and enabled trust on Ubuntu/grub .efi boot files? Is UEFI/BIOS resetting to defaults not saving configuration? Acer Aspire E15 will not dual boot, many details Trust settings in step 35
http://askubuntu.com/questions/627416/acer-aspire-e15-will-not-dual-boot
 Have you upgraded to newest UEFI from Acer. Some older threads mention downgrading to get things to work, but newer ones say to upgrade to newest UEFI works.
Answer: Simply Hold The shift key right after the machine splash screen.
please clarify your question if my answer isnt helping

GRUB doesn't load up


How do Hogwarts candidates disappear from their muggle lives?

Question: Neighbours, schools and government systems will assume a missing child if they move out of their homes to Hogwarts. How do they keep their old identities in sync with going to a place unrecognised by muggles?
Comment: They're not missing...they're in a private boarding school.
Comment: For the record, thousands of children in the UK go "missing" each year. For the most part, they're simply being moved overseas or elsewhere in the country.
Comment: "Neighbours, schools and government systems will assume a missing child" - no they won't. That's not how it works.
Answer: Going to Hogwarts is no different from going to any other boarding school.  They disappear during the school term and reappear over the holidays; it would be easy for parents to explain that they are at a boarding school.  For example, the Dursleys made Harry tell Aunt Marge that he attended St Brutus's Secure Centre for Incurably Criminal Boys.


Is there any threat to the results of our effective field theories from unknown higher energy theories?

Question: We use renormalization arguments (and experiments) to change the couplings of a theory and suppress the higher energy physics (saying things like "whatever the fundamental theory, this will be true of the low energy theory."). And we then get some set of fields, correlation functions, etc. My question is just about the possibility of, say, a theory of quantum gravity that compromises the renormalization arguments we'd been using to determine the sensitivity of EFTs to the space of possible high energy theories. So, perhaps the actual theory wasn't included in the high energy theory space?
Comment: For one, we know EFTs are useful because we have experimental data to compare its predictions with (and dispel any serious doubts about its usefulness). Theory must explain data, not the other way round.
Comment: There is no 'right' theory when one talks about EFTs. The Schrödinger equation is not predictive for $p<m$ while the Dirac equation is (because it is relativistic). But it doesn't mean that one is right and the other is wrong; they are both *useful*, in their own regimes of validity.
Comment: @Avantgarde Interesting! I wonder if someone might respond by asking "how do you know that you've found the right theory, when other theories might explain the data just as well?" And what the response to them would be.
Comment: I might be misinterpreting you here, but I meant to include the regimes of validity in that question. So, we have a low energy theory of quantum gravity valid at scales below the Planck scale. And then someone poses the question I first asked and the one I asked in response to you.
Answer: Physics theories model experimental data. Starting from the very successful Maxwell equations solutions, which model macroscopic electromagnetic behavior, the the solutions of Schrodinger's equation which clarified the spectra of atoms, to the good fit of the present standard model of particle physics to almost all data accumulated from the 1960s, physical theories are an encapsulation of a great lot of measurements, if the are successful. They are successful if they can predict new measurements correctly. If they are not falsified, they are considered validated and standard.
Thus , if a possible higher energy theory for quantum gravity does not embed the lower energy effective field theories, it might be a competing theory for gravity, but not for a theory of everything, in effect it will be a different effective theory.
A theory of everything headed by quantum gravity should embed all the validated by data effective field theories, otherwise it is falsified as a theory of everything.
The data trumps mathematics. Of course it might mean that nature has not given us a theory of everything
Comment: Thanks for the response, @anna v! Going along with your answer, I guess I'm trying to ask whether anything specific to the high energy theory could compromise the claims our EFTs make at the scales/energies they're defined at. So, the low energy theory of quantum gravity, or quantized GR, makes some claims about dynamics at low energy. If someone tells us that "the high energy theory might not even be a quantum field theory, and so you can't use the RG flow to say how sensitive your theory is to the high energy theory," are they justified? Or do we just invoke the empirical data agreement?
Comment: In general, we are in the stage of reseach where mathematics has to be used to model nature, not words, as in older times, as with mathematics we can look to consistency with data. A chariot pulling the sun is a nice fairy tale in our age, it was considered a working proposition three thousand years ago. So "...and so you can't use the RG flow to say how sensitive your theory is to the high energy theory,"  is equivalent to a chariot in the sky. Only if the statement has hard mathematics that model data will be even considered. (just searched what RG flow is btw, too many abbreviations ).


1x9 wide range cassette

Question: I am curious to find out if anyone has figured out a viable solution for a 1x9 wide range eg; 11 to 46 or 11 to 50 setup without using a derailleur hanger extension? I have a FS mtb and am not too concerned with large steps between gears. It's currently a 9 speed hg401 11 - 36 with a Shimano RD-M370 long cage and with the B screw all the way out I have a solid 10mm between the RD pulley and cassette in 1st gear. I don't want to go with more speeds unless there's a less expensive solution than replacing only the cassette and possibly rear derailleur. I can't find a 10, 11, or 12 speed groupset for less than $150ish and that's a cheap setup.
Answer: The Microshift Advent is a 9 speed derailleur that they say is rated to a max cog size of 42-46, with a capacity of 47, so it should be fine for an 11-46 setup. Only compatible with their shifter according to them, so it might not come in under your budget if you include the cost of cassette, derailleur, and shifter, but it's preobably pretty close.
Comment: I was looking at that groupset in 10 speed and with a decent 10 speed chain is almost $200. That's not by any means expensive but this is a cheap used bike that I just bought for playing around on the Denver area trail system. I only paid $100 for the bike so I'm trying to not spend a lot on it because if I stick with it I'm going to invest in a decent bike. This one wasn't bad in its day but it's an 08' with crappy suspension components. I serviced the forks the best I could without a proper kit with the wipers and seals etc, the rear strut is ok but still a cheap model. It's a good starter.
Answer: Sun Race makes a wide range 9-speed cassette the CSM980 which is an 11-40T. That's pretty good range and the cassette is quite inexpensive (looks like aprox $35 USD after a quick google). If you need a bit more space you can get a longer b-screw.
Next cheapest option would be grabbing an inexpensive wide range 10-speed cassette (Sun Race being the usual option) and an old long cage 10-speed Shimano derailleur and shifter (and 10-speed chain obviously). Depending on where you source parts this could be fairly inexpensive. You may need a longer b-screw. There are lots of guides on old forums on doing wide 1x10 setups (that was quite popular before 11 and 12 speed became accessible).
More expensive but an amazing deal would be a brand new Shimano M4100 group. It can be found overseas for around $100 USD with derailleur, shifter, cassette and chain. The cassette options are 11-46T or 11-42T. The derailleur may have the serial scratched out (as is often the case with bulk oem parts being sold likely against their contract). I think retail pricing is over 2x that price.
Answer: Well, I have it working fairly well. In hindsight I wish I would have gone with the complete Microshift Advent setup but that's how it goes for me being a stubborn miser. I got a Sunrace 11 to 46t 9 speed cassette. My existing rear derailleur works but I did have to use a hanger extender. I also had to get and modify a steel hanger because the aluminum one just couldn't take the load of the shifting with the additional length.
I had to remove some material from the steel hanger to make it fit the dropout and it still sits at a different angle which puts the derailleur mount a little further toward the rear of the bike and I think a little higher as well but with the b-screw all the way in I have just enough clearance so that it doesn't crash in the lower gears. I may remove a little more from the hanger next time I have it apart back there or if it starts crashing with use/wear so that it puts the mount hole closer to where it should be.
But if I don't have any issues I may just leave it where it is because of the last section of the cable. In order for the cable to not seem like it wants to kink where it goes into the barrel adjuster I had to use a longer than usual section of housing back there to provide adequate travel of the rear derailleur with the longer travel from the wide range cassette. With the derailleur positioned further back and upright it eases this condition and allowed me to shorten up that last piece of cable so that it's tighter to the frame and less likely to get caught on things out in the wild.
Comment: Update, I did have to install a chain guide on the chainring to keep it on. It was fine on normal road and paved trails but on more demanding and uneven dirt trails it did come off a couple of times. The guide solved this issue.

1x9 wide range cassette


DC motor spun clockwise then counter clockwise creates AC current?

Question: I am making a generator with a DC motor but the style of turning the rotor would be clockwise and then counter-clockwise, and I would want to capture as much current as possible so I hope it could be turned into AC current somehow.  If so how?
Answer: Well, if you reverse direction you will have an AC voltage at the motor terminals, frequency proportional to the period of reversal, peak amplitude proportional to peak shaft speed. It isn't necessarily sinusoidal unless the shaft speed is sinusoidally driven. This is assuming you are talking about a DC brush motor?  A brushless DC motor will give you an AC voltage at the terminals if you drive it in either direction.  Frequency and amplitude will be proportional to shaft speed.
I don't get the link between capturing as much "current" as possible and converting the output to an AC voltage, maybe you could explain a little more about what you are trying to accomplish?
Comment: I am trying to harness the energy of a bolt (that I would attach the motor to) that spins rapidly clockwise and then changes direction and slowly spins counter clockwise back and then changes direction again and cycle repeats.
Comment: OK, that part is clear, but what are you trying to do with the output of the motor? Charge a battery? Just not clear on why you want AC vs. DC, since for most purposes you're just going to have to convert it to DC anyway.
Comment: yeah I am trying to charge a battery.  But since the motor changes direction, I thought that that creates AC yet DC is needed for charging a battery.  AC would be unpredictable I would think based on the inconsistency of the speed of the spinning bolt, which is why I asked, because rather than only getting DC when the motor is turned clockwise I thought it would be more efficient to get the current generated from clockwise spinning as well as counter-clockwise spinning in AC
Comment: I see-  What you want to do is put a full-wave rectifier on the output to change the AC to DC, probably followed by a large electrolytic capacitor to smooth out the DC voltage.  Then you have a shot at a stable DC source you can use to charge a battery.  You could use a Schottky diode bridge for better efficiency if the output voltage of your motor isn't too high.


What is the true way to determine time parameters from semilog graph?

Question: I have experimental nuclear magnetic resonance data that describe T2-relaxation of the nuclei in the sample of interest. The experimental points obey bi-exponential dependence: I = I1*exp(-t/T2_1) + I2*exp(-t/T2_2), where I is current intensity, I1 and I2 are intensities which represent fractions of two T2 components - T2_1 and T2_2. The purpose is to calculate T2_1 and T2_2. To calculate T2_1 and T2_2, I fit bi-exponential equation mentioned above to experimental data points. But in order to ensure that calculated T2 values are true, I'd like to build semilog graph. For this, I take natural logarithm of experimental intensities, and thus the vertical axis in the graph is now in ln(I). Then, in obtained semilog graph, I need to divide points into two parts: first part of points will be fitted by linear equation y1 = C1 - t/T2_1, and the second part of points will be fitted by linear equation y2 = C2 - t/T2_2. And here I have two variants of how to do this fitting. The first variant is just to fit each part of data points with linear equation with corresponding initial guesses. And the second variant is the following: first, I fit the second part of points with equation y2 = C2 - t/T2_2, i.e. 7 points as you can see in the attached images. Thus I found C2 and T2_2 from fit. Then, using equation y2 = C2 - t/T2_2, I find ln(I) values for time values corresponding to the first part of points (i.e. first 3 points as you can see in the attached images). After that, I subtract these extrapolated ln(I) values from first three experimental ln(I) values. Let's call these new values as ln(I)1, ln(I)2, ln(I)3. Finally, I fit these 3 points with equation y1 = C1 - t/T2_1 and find the parameters C1 and T2_1. Could you please tell me, which variant of calculating T2 values is true? Please find attached two images which show the difference between two mentioned methods of calculating T2 values.
Answer: I would say that neither of your two methods is strictly correct, but your 2nd method would result in a more correct result than your 1st method. The problem with your 1st method is that you can't say that the first part of the signal decay is strictly associated with only the $T_{2 1}$-type decay process. In truth, both decay processes, $T_{2 1}$ and $T_{2 2}$, are simultaneously occurring both before and after the "kink" in the data. You seem to be tacitly assuming that the observed decay in the data before the kink is only associated with type $T_{2 1}$ decay, and that the data after the kink is only associated with type $T_{2 2}$ decay, but that's not so. Both decays are occurring throughout the displayed time interval, as indicated by the equation that you yourself wrote down of I = I1*exp(-t/$T_{2 1}$) + I2*exp(-t/$T_{2 2}$).
Your 2nd method at least recognizes the fact that type $T_{2 2}$ decay is occurring in the first time interval and tries to subtract out that contribution, but the problem is that type $T_{2 1}$ is also occurring in the second time interval, so strictly speaking it isn't correct to assume that red lines shown in your fits reflect pure type $T_{2 2}$ decay. There is also a little bit of type $T_{2 1}$ decay in the 2nd time interval. In practice, though, the type $T_{2 1}$ decay shown in your plots is so rapid that there is probably very little error in just fitting the 2nd time interval and assuming that you've measured $T_{2 2}$ from that, so that's why I say that the 2nd method is probably much more accurate, even though it's not rigorously correct, either.
If you want to be rigorously correct, you would have to do a least-squares fit of the entire set of data points shown to the function I(t; I1, $T_{2 1}$, I2, $T_{2 2}$) = I1*exp(-t/$T_{2 1}$) + I2*exp(-t/$T_{2 2}$), where I1, $T_{2 1}$, I2, and $T_{2 2}$ are the fitting parameters.
Comment: Thank you! Initially I fit the function I(t; I1, T2_1, I2, T2_2) = I1*exp(-t/T2_1) + I2*exp(-t/T2_2) to the entire ser of data, and thus I obtained values for fitting parameters I1, T2_1, I2, and T2_2. But my supervisor told me that I should fit y2 = C2 - t/T2_2 to the second part of points, then extrapolate this fitting line for the time values corresponding to the first part of points, then subtract extrapolated values from the first part of points, and finally fit y1 = C1 - t/T2_1 to these new points.
Comment: But I have doubt regarding this method, because T2_1 value obtained using this method (when subtracting extrapolated values from the first part of experimental points) is further from the truth than the T2_1 value obtained using the method when subtraction is not applied (Top graph in my main post). I.e. if I just fit first part of data points with linear equation, I get T2_1 value that is close to the truth.
Comment: In the first comment: when I wrote "But my supervisor told me that I should fit y2 = C2 - t/T2_2 to the second part of points, then extrapolate this fitting line for the time values corresponding to the first part of points, then subtract extrapolated values from the first part of points, and finally fit y1 = C1 - t/T2_1 to these new points.", I meant that I should do these steps in semilog graph, i.e. taking natural logarithm of intensity values.
Comment: @Leonid - I think that the method that your supervisor is suggesting should give a fairly accurate result because the T2_1 decay is so rapid that its contribution to the signal is nil after the first five points. So you can regard the following points as being pure T2_2 decay. The results you get for the decays by this method should agree very well with the full entire data fit method. You wrote that you used the entire data fit method that I suggested. So how well did the T2_1 and T2_2 decays agree with the decays that you obtained using your supervisor's suggested method?
Comment: The 1st method which you described (no subtraction used) is incorrect because the slope of the data points in the first part of the decay before the kink is a function of BOTH the T2_1 decay AND the T2_2 decay. That's the point of your supervisor's suggestion to do the subtraction. By subtracting out an appropriate amount of signal from the data points of the first amount of decay, you take out the influence of the T2_2 decay and are left with new data points which more accurately reflect pure T2_1 decay.


How can I make the Galaxy S3 detect media on my sdcard?

Question: I have transferred some mp3s onto my sdcard using samba but the operating system doesn't seem to automatically detect them as it would if you copied it using MTP or whatever.  How can I force it to detect them?
Comment: do they show up after a reboot? If so you probably just need to get the media scanner to run. See the answer to this question: http://android.stackexchange.com/questions/9449/how-do-i-play-mp3s-from-my-dropbox/9451#9451
Answer: My S4 wouldn't recognize music on my external SD-card. You can fix this on your S3 by going to settings> more > storage > remove SD-card. Wait till it says 'You can now safely remove your SD-Card' then remove the card out your phone. Clean your RAM and then put it back in again. Wait a few seconds till it's succesfully installed and your card will be visible. I.E for music open your music player and it'll all be there. Make sure the files aren't in too many subfolders or your phone will not find it and show it in your music player.
Have a nice day,
Answer: Run the following shell script on the command line, either via SSH or adb.
<code>#!/system/bin/sh<br/>

export ANDROID_ASSETS=/system/app
export ANDROID_CACHE=/cache
export ANDROID_DATA=/data
export ASEC_MOUNTPOINT=/mnt/asec
export ANDROID_ROOT=/system
export BOOTCLASSPATH=/system/framework/core.jar:/system/framework/core-junit.jar:/system/framework/bouncycastle.jar:/system/framework/ext.jar:/system/framework/framework.jar:/system/framework/android.policy.jar:/system/framework/services.jar:/system/framework/apache-xml.jar:/system/framework/filterfw.jar
export EXTERNAL_STORAGE=/mnt/sdcard
export LD_LIBRARY_PATH=/vendor/lib:/system/lib

am broadcast -a android.intent.action.MEDIA_MOUNTED -d file:///mnt/sdcard
</code>
Source: Can I trigger a media scan via the command line?
Alternatively if you prefer a UI I find Force Media Scan ideal. You do not have to reboot your device for these.


What does an 'organic' letter mean?

Question:
simultaneous (adj.) [:]
      1650s, from Medieval Latin simultaneus, perhaps from simultim "at the same time," extended from Latin simul "at the same time" (see similar (adj.)), or from simul with ending abstracted from Late Latin spontaneus, where the -t- is organic. [...]
Answer: It means that in spontaneus the t belongs to the root of the word, it's an organic, natural part of that word, while in simultaneus the t and the whole ending -taneous was abstracted from spontaneus and added to the word simul 'together'.
Comment: Note that talking about "letters" is a category error. The whole discussion is about sounds.
Comment: In this case, phonemes that are part of morpheme stems, or not. So the root is _spont-_ (ending in /t/) in one case, but _simul-_ in the other.

What does an 'organic' letter mean?


Windows ToolBar-dockable application

Question: How to create a windows toolbar-dockable application - like Winamp Desk Band - in .NET?
Answer: It sounds like you want to create an AppBar.
I suggest you first check out the AppBar implementation included with the Genghis package. I couldn't say if it's any good since I never used it, but it looks promising.
Manually, you would have to use a few Win32 API calls to reserve/free the screen space and achieve the effect you're looking for, as detailed in this article.
Good luck!
Answer: C# does Shell, Part 3
http://www.codeproject.com/KB/shell/csdoesshell3.aspx
AppBar using C#
http://www.codeproject.com/KB/dotnet/AppBar.aspx
Answer: As a commercial alternative, see the ready-to-use ShellAppBar component which supports all cases and secnarios such as taskbar docked to left,right,top,bottom edge, support for multiple monitors, drag-docking, autohide , etc etc.

Windows ToolBar-dockable application


Per-site Meta reputation updating... slowly

Question: I answered a question on Stack Overflow and it got an upvote. After a great several minutes I went to Meta Stack Overflow, and was surprised that my reputation was still 10 less than main, indicating that it was not up to time. Dear me it's been a quarter. Then I tested on another site and it seems to have the same problem. How can that happen?
Comment: No bug here. The cache might be for one hour. You can start feature request asking to reduce the time, e.g. to 5 minutes, but I don't really see the point.
Comment: @ShadowWizard You must have been the *de facto* living database of MSE.
Answer: It has always been this way - the per-site metas don't update reputation on their main sites fast.
The reason is presumably the load on the server. Especially on the bigger sites like SO, synchronizing the reputation of all users must be an arduous process. But this synchronization does not affect the functionality of the site much. Only if a user crosses a reputation threshold, does it affect their ability to take actions on the per-site meta.
So, it is quite reasonable for the per-site metas to not synchronize the reputation levels too often.


How to integrate Rasa Chatbot into website?

Question:
I have installed Rasa Core and NLU in my computer and after training
  and build the models now my chatbot is ready but I'm not getting clear
  documentation or way to deploy or integrate with a website.
I have 'Rasa' named folder and 'venv' virtual environment. I tried to
  put it into a website but they are blocking the files. So what is the
  method to put the Rasa chatbot into the website for 24/7 live chat?
Comment: This link might be helpful:  [Rasa deployment](https://rasa.com/docs/rasa-x/enterprise/deployment-environments/)
Comment: @Sociopath as a beginner I'm not getting those exactly, can you simply the way how it should fix the problem?
Comment: If you have core and nlu separate then you need to upgrade soon. After >= v1.0, core and NLU server have been merged.
Check this out on how to use rest APIs to create your own UI for your website: https://rasa.com/docs/rasa/user-guide/connectors/your-own-website/#id2
Comment: @jainmiahshaik did you find a solution? there's no tutorial or good documentation for deployment on a live website using rasa-nlu
Answer: For connecting your chatbot to a website, try using https://github.com/botfront/rasa-webchat i.e. "A chat widget to deploy virtual assistants made with Rasa or Botfront on any website." You'll need to add something like
socketio:
  user_message_evt: user_uttered
  bot_message_evt: bot_uttered
  session_persistence: true/false

to your credentials.yml. See https://rasa.com/docs/rasa/user-guide/connectors/your-own-website/ for further details on connecting to your own website.
In terms of deployment, the recommended way to deploy a rasa chatbot is using Rasa X using either docker-compose or kubernetes/openshift. The easiest way would be to use the one line deploy script.
Answer: https://rasa.com/docs/rasa/connectors/your-own-website/#id2
after training your bot run the command
rasa run --enable-api --cors "*"
Add the REST channel to your credentials.yml:
rest:
  # you don't need to provide anything here - this channel doesn't
  # require any credentials


Remote connection to DB instance from fresh formatted system?

Question: I have 1 win7prof  fresh system. Now I want to connect to a DB instance remotely via sqlcmd/any other way. My req is  to connect and execute select query? is there any method/software needed to be installed in fresh win7prof system to access the instance.? kindly let me know what to do for access and use manipulation operations ?
Answer: I checked this out and the latest available standalone for SQL Server Management Studio is a 2008 version here.
Thanks to @AaronBertand, the process of obtaining the SQL Server Management Studio 2014 involves clicking the download button for the full SQL Server Express 2014 and then you will be offered a choice of only downloading the Studio (see here - with thanks again to Aaron Bertrand). Detailled instructions available here.
If you just want a command line client, then check out this post.
Comment: There should be a standalone installer for SQL Server Management Studio Express 2014 [here](http://www.microsoft.com/en-us/download/details.aspx?id=42299) or for 2012 SP2 [here](http://www.microsoft.com/en-us/download/details.aspx?id=43351). These will be better than 2098 for two reasons: (1) they are full functional (lots of restrictions in the 2008 version) and (2) if the OP is managing any versions > 2008, the 2008 client will not be capable of performing some tasks that it isn't aware of...
Comment: Maybe I haven't understood how Microsoft do things (wouldn't be the first time :-) ), but your link gives the entire SQL Server Express - I couldn't see a Management Studio Express 2014 download on that page (2008 Management Studio is available there). Do you have to start the process of downloading the 2014 Express, then to be offered the Management Studio choice as a standalone?
Comment: No, see http://dba.stackexchange.com/a/73919/1186
Comment: So, it appears that Microsoft does indeed make life a bit counterintuitive. They've decided not to release the Management Studio as a separate download. However, it can be installed separately on launching the SQL Server Express download. I'll update and clarify my answer. Thanks for that.
Comment: Well, that's not quite accurate. When you click Download, there is an option to select just a Management Studio installer ([see this](http://i.stack.imgur.com/twNOv.png)). The setup program, though, is generic, and doesn't *know* that the package is meant to be Management Studio only.


Is the "clear" button still necessary in a contact form?

Question: I'm putting together a basic contact form for a standard business/company site. First name, last name, email, phone number and message. I was tempted to put a "clear" button to clear the form and I thought to myself is this necessary. IE puts the clear marker at the end of each field. Is the clear button necessary for the contact forms?
Comment: After reading Devin's answer and your comment on it, I realize there could be a need for a clear button. Browsers can fill in forms automatically and how many users know how to undo that? I can see it being usefull for a contact form but not really for surveys. Maybe you can share a bit of your research to give the question more context and get better answers.
Comment: Thank you. I simplified the question. Hopefully that will help.
Answer: Well, it was old almost from its own conception. Think about this: how many times will you need to clear ALL info in ALL fields of a form? Now ask anyone you know and you'll probably have a very basic research study that will propably yield an absolute result: NEVER.
And like I said, even at the beginnings (well, almost) of web applications this was considered an useless element. As early as year 2000, Jakob Nielsen advocated for the ban of the clear and reset buttons, with some caveats. And of course, that article is old and some of the views on that article aren't very valid nowadays, but still worth a reading. See what he said about the cancel button:

Cancel: Use Sparingly
The Web is not an application environment, and it usually doesn't have
  dialog boxes. Instead, the Web is a navigation environment where users
  move between pages of information. Since hypertext navigation is the
  dominant user behavior, users have learned to rely on the Back button
  for getting out of unpleasant situations. Whenever users arrive at
  pages they don't want, they slam their mouse directly onto the Back
  button.
Because Back is such a strong behavior on the Web, it is usually not
  necessary to offer explicit Cancel buttons. If the user asks for
  something but doesn't want it, then you can be sure that it's Back
  button time.
Offer a Cancel button when users may fear that they have committed to
  something they want to avoid. Having an explicit way to Cancel
  provides an extra feeling of safety that is not afforded by simply
  leaving.
Cancel is mainly useful for multi-step dialogs where the user has
  progressed past one or more pages with actions. At this time, pressing
  the Back button will not undo these actions and it would be better if
  the user would click Cancel.
Of course, one cannot rely on having the user click Cancel , even if
  it is offered, so the back-end logic must be able to handle abandoned
  multi-step dialogs where the user decided to leave through the use of
  the Back button. This added complexity is one of the reasons I don't
  recommend trying to implement advanced applications inside a Web
  browser. It is better to use another form of Internet-enabled
  applications.

Also, the clear button adds some complexities to the flow:

the cancel/clear button in forms users may accidentally click that button and there's no confirmation messages to cancel that action, which adds a lot of frustration
it adds an additional level of friction, because there's another possible action, making the user guess why is that there
affordance is confusing: what are you going to clear? what are you going to cancel? what are you going to reset? See how all these words are used for the same button, yet they all do and serve for different purposes. Now think that the user has seen all these option many times, sometimes well used, sometimes not. What are you going to use that doesn't add friction to the experience?
finally, what problem does the clear/cancel button solve? What additional benefits provide?

In short, it's quite easy to see that button is quite useless, as long as you don't need to use it where Nielsen mentions (multi-step forms, upload/download data and such, in that case you'll need a CANCEL button rather than a CLEAR button)
Comment: The first three people I surveyed have used the clear/reset button. Including me that would bring the total up to four. Your assumption doesn't hold up.

Nielsen's argument doesn't support yours, he never says the clear/cancel button is a useless element. While his argument is based on the theory that the web is not an application based environment (There was no google at the time) he also that the user would prefer the back button. This would take the users away from the form I would like them to fill out.

There are too many flaws in your answer to be accepted or even to fit into a comment.
Comment: Your first point about the cancel/clear happening accidentally; this is a major pain and I would do anything to avoid the potential of this. If the user really wants to clear out the form they will simply refresh the page
Comment: Read the "Reset" part of the article, which is the closest to "clear", although they're not exactly the same. I added the cancel explanation for cases in which you actually may need the button. For *Reset (clear*), here's Nielsen's advice: **Reset: Don't Use**
Answer: It depends on your situation; a simple one page contact / enquiry form does not need a reset form. Why would you need to reset anything since nothing has been stored yet. If you really need to start over, you could always just refresh the page.
However, if you have a form consisting of multiple pages, the filled in fields have most likely been stored in for instance a session. In that case you should offer a reset button as of the second page.
I would say it depends on wether or not any data has been saved yet that can be cleared.


MatSnackBar: Colors have no effect

Question: I have trouble adding a CSS class to MatSnackBar.
this._snackBar.open('✔ Saved', '', {
  duration: 3000,
  horizontalPosition: 'right',
  panelClass: ['snackbar-success']
});

.snackbar-success
  background: $success
  color: #fff

It used to work before but since I have updated Angular Material to 17.0.4, it doesn't work anymore. I now have updated to 17.0.5 and it still does not work.
Basically, the CSS class is getting added but it has no effect. It seems as if it is being added in the wrong place.
This is what i see in DOM:

display: none !important works but in my case I am using colors. I tried color, background, background-color, and all of them with !important but none of them worked.
Am I doing something wrong or is this a bug?
Answer: Here how you can change the colors of mat-snackbar:
.mat-mdc-snack-bar-container.snackbar-success {
  --mat-mdc-snack-bar-button-color: #fff;
  --mdc-snackbar-container-color: #28a745;
  --mdc-snackbar-supporting-text-color: #fff;
}

Comment: Thanks! `--mdc-snackbar-container-color:  $success` did not work for me. I have changed it to `--mdc-snackbar-container-color: #{$success}` and now it works fine.

MatSnackBar: Colors have no effect


Where is the best place to perform a run-up at a busy airport?

Question: If you wait to perform a run-up at the end of a taxiway at a busy airport you will probably not make many friends.  Some airports may have designated run-up areas or have runways designated for general aviation but at those that don't would it be acceptable to do a run-up on the ramp before you taxi?
Comment: If you at an unfamiliar airport, you can ask the FBO or your instructor. At my airport we can do run-ups at any unoccupied part of the ramp (just don't blow rocks/dirt at aircraft/people).
Answer: In my humble opinion it is best to ask the FBO for their practices or do it at the ramp with precautions as not to hurt or disturb anyone or anything.
On the Taxi way you might run into difficulties returning to the ramp in case something does not look or perform right during run-up. When in dout I ask Ground for advice.
Comment: At the end of the taxiway is better, as plugs can foul during a long taxi out to the end of the runway. And at some airports it is pretty long. Runup at the end gives a last chance to get the engine hot and clear them up prior to taking the runway.   At Nantucket for example, if you are parked near the intersection of 15 and 24, but are taking off to the northeast on 06, then you would taxi almost the full length of 24, past the airport and FBOs and other general parking.  Plenty of time for plugs to foul, especially if you had forgotten to lean out the mixture while taxiing, for example.
Answer: Most airports have a place to pull off left or right near the end of the runway to allow turning towards the runway (maybe not quite perpindicular at small airports) for the runup before pulling up to the hold short line. If not, there is typically enough room to at least turn & hold short while running up to not blast the guy behind you.
If you have a problem after that, you can likely get clearance to taxi down the runway and pull back nearer to where you started to find an FBO for help. Or back to parking if the FBOs are closed. Non-towered airport, wait for the runway to clear, then announce and pull out and taxi to where needed.
At smaller airports, there will be a place, maybe nearer parking and parallel to the runway, where you can runup before taxiing, or backtaxiing, to the end of the runway for takeoff.  9B1, Marlboro, MA, is one such airport. The paved runup area is above the word MARLBORO, or out in the grass north of the runway.
https://www.google.com/maps/place/Marlborough,+email@example.com,-71.510151,255m/data=!3m1!1e3!4m5!3m4!1s0x89e38b0e6861ee6d:0xc7e9aa4b55f5afc4!8m2!3d42.3459271!4d-71.5522874


How is Boba Fett alive?

Question: In Return of the Jedi, Boba Fett falls into the Sarlacc pit and we hear an audible belch from the pit. However, Boba makes an appearance in The Mandalorian season 2, and it's revealed that the next season will be about him and set at some point after the events of RotJ. So how is he alive if he was eaten by the Sarlacc?
Comment: Is "retcon" an acceptable answer, because I think they've yet to fully explain it (if they ever do). Wikipedia covers the retcon, but it contains no real explanation short of what we see on screen. https://en.wikipedia.org/wiki/Boba_Fett#The_Mandalorian
Comment: probably ave to wait until The Book of Boba Fett, but I want to know too! :D
Answer: As I remember, C3PO translated something whch Jabba said as meaning that people fed to the sarlacc would be slowly digested over a thousand years.
So Jabba claimed that victims of the sarlacc would take many centuries to be digested.  And I think the implication was that they would somehow be alive and in pain for those many centuries.
I don't know wheter Jabba was telling the truth, but as far as I remember the sarlacc didn't bite Boba Fett but simply swallowed him whole.
So Boba Fett was still alive and conscious when he entered the throat of the sarlacc, and might not have been killed or knocked unconscious when he stopped falling into the sarlacc.
If Boba Fett was alive and conscious inside the sarlacc, he would have his armor on and been carrying his weapons.  And if being digested was painful he would have been even more highly motivated to use his tools and weapons to escape from the sarlacc.
The main problem with imagining that Boba Fett escaped from the sarlacc sometime after entering it is that the sarlacc's digestive tract would probably not have much or any oxygen to breathe.  Thus Boba Fett might have had only a few seconds of consciousness before becoming helpless and dying soon after.
Of course if the sarlacc did somehow keep its victims alive for a millennium, Boba Fett could have taken years to find a way to escape from it.
As I remember, the fight at Jabba's sail barge lasted for a few minutes after Boba Fett flew into the sarlacc's mouth, which is more than enough time for someone to lose consciousness and die from lack of oxygen.  Boba Fet t was not seen escaping from the Sarlac during that time.
But the camera angles changed a lot during the battle. During that time the camera switched from a wide view to a narrow view, and back again, many times. And the direction that the camera pointed at changed many times.  The mouth of the sarlacc was not visible all during the battle.
So it is possible that Boba Fett landed inside the sarlacc, reorientated himself, and turned on his jet pack again and zoomed out of the mouth of the sarlacc when the sarlacc's mouth was not in view of the camera.
Boba Fett might have zoomed upwards for hundreds of feet and then descended, again off camera, and landed some distance from the sail barge behind a large sand dune.  And maybe he was so shaken from the experience of being inside the stomach of a man-eating monster that he just collapsed helplessly on the ground for a long time, and didn't recover his composure until long after the battle was over.
According to Wikipedia:

Fett appears extensively in the Star Wars Expanded Universe of novels, comic books, and video games, dating to as early as the newspaper comic strip and Marvel's Star Wars series produced concurrently to the original Star Wars trilogy. In April 2014, these works were rebranded by Lucasfilm as Star Wars Legends and declared non-canonical to the rest of the franchise.[26][27][28]
Works such as Dark Horse's Dark Empire series (1991–1992) describe Fett surviving the sarlacc.[3] A 1995 anthology story by Daniel Keys Moran narrates some of his time in the sarlacc, and a 1996 story by Dave Wolverton narrates how Dengar finds him and restores him back to health. In the comic Boba Fett: Twin Engines of Destruction (1997),[c] while Fett recovers after being freed from the sarlaac, he is impersonated by a bounty hunter named Jodo Kast, whom Fett then hunts. Four Boba Fett comics set several years after Return of the Jedi were released between 1995 and 2000.[d] Fett encounters Han Solo in a short story set 15 years after the events of the same film,[29] and fights side by side with him in The New Jedi Order: The Unifying Force (2003), set a further decade later. He also appears in the e-novella Boba Fett: A Practical Man, set 20 years after Jedi. In the Legacy of the Force series (2006–2008), set some 35 years after Jedi, Han and Leia's daughter, Jaina, asks Fett to train her to help her defeat her corrupted brother, Jacen.[e]

https://en.wikipedia.org/wiki/Boba_Fett[1]
So in the Star Wars expanded universe, there is at least one account of Boba Fett surviving the sarlacc.  The expanded universe was once considered to be canon, but has been declared Star Wars Legends.
It is possible that the canon explanation - if one is ever stated - for Boba Fett's sarlacc survival may be identical to the one(s) in some Star Wars Legends stories.  Or it may be totally different.  Or it might resemble the Stars WArs Legends account(s) in some ways and not in others.
Answer: In the Bounty Hunter series of books from the EU, Boba Fett blows up the Sarlacc, and Dengar nurses him back to health.
In The Book of Boba Fett, we are shown Fett using his flamethrower to burn through the stomach of the Sarlacc.
Comment: Hello and welcome to Movies & TV Stack Exchange! While your answer is helpful, it would benefit to have a source and/or provide more specific information (such as the episode title/number) or even mention that this shown in a flashback sequence, etc.

How is Boba Fett alive?


Will I go through immigration/need a visa if I don't have checked luggage?

Question: I have a cheap flight booked to Bangkok that connects in Mumbai where both legs are seperate bookings.
According to the website I booked it through (kiwi) I will leave the transit zone in Mumbai and need a transit visa but through my research it seems you only leave the zone if you recheck luggage or go to a hotel or something like that. I will only have hand luggage and my stop is only a couple of hours so no hotel required.
Will I still need to go through immigration?
Comment: If this is booked as a self-transfer, you may find that the first airline considers your *final destination* to be Mumbai irrespective of your luggage arrangements. So you could be denied boarding unless you have the right travel documents to enter India
Comment: Do you have a passport that allows visa free or visa on arrival in India?
Comment: For a more specific answer, please edit your question to include your citizenship, where you would be arriving from, the airlines involved (ideally the specific flights), the times of arrival/departure, the respective terminals.
Comment: Email the handling agent at the departure airport and ask if they'll let you board with this itinerary without papers for entering India
Comment: Not passing from immigration doesn't necessarily mean you do not need a (transit) visa. Also consider delays. And you are welcome in this site. I just checked the Mumbai airport website and ... good design but they avoid to provide information (for sure nobody care about content: transit you are required to look transit faq, which do linkt to the wrong section, but the transit section repeat the question mostly irrelevant to transit (and repeat again the same question, just to increase the number of questions)
Comment: Related: https://travel.stackexchange.com/a/171372/30703
Answer: Assume you will not be let onto the first flight unless you have the right to enter India, as that is the standard for most airlines.
Whether you need to go through passport control, customs (even without hold luggage you may be checked) and check-in and security depends on the actual airport and in some cases the combination of flights.
I am not familiar with the airports in India, but it is quite common world wide to send all passengers on incoming flights through immigration, and have them re-enter the airside of the airport after checking in for the next flight.
You might be lucky and stay airside, but you will still need to be allowed into India, as the airline can not be sure you will be allowed on your next flight and they are responsible for you entering or leaving India.
Comment: Correct, having luggage or not has nothing to do with your permission to enter a country legally.
Comment: Since when is it "quite common world wide to send all passengers on incoming flights through immigration"? In my experience, the opposite is the case for major airports, especially hubs, with the US the only major exception that comes to mind.
Comment: @Relaxed, recently we have had a few questions about transfering in the UK in airports other than Heathrow and about Ireland, in which cases the incoming passengers had to leave the airside area. I think I have heard it about Australia as well but I am not certain there. And in Paris (I think CDG airport) you have to go through immigration if you are unlucky with the terminals. And those is only the ones I have heard about, enough to warn OP that it might happen.


web3 js php implementation

Question: Is there any way to communicate with ethereum through php ? what i want is to get Smart contract details from contract address like Contract token name, decimal, abi, balance, tokens supply symbols etc. till now what i know is web3.js is a official library to interact with ethereum but there is no implementation in php. I have limitation i cant use js, only option that i have is php.
Let me know if there is any web3.js implementation or any other way to interact with smart contract through php.
Answer: There is currently
https://github.com/digitaldonkey/ethereum-php
and more recently
https://github.com/web3p/web3.php
Answer: web3.js doesn't communicate with the Ethereum network directly. Instead, web3.js connects to an Ethereum node running on the user's computer such as Parity, MetaMask, Mist or just geth. This node in turn communicates with the Ethereum network.
You cannot use web3.js with PHP, because it is written in and for JavaScript only. There is no official implementation of web3 in PHP.
You will have to use PHP to communicate with a local Ethereum node. I recommend doing this through its JSON RPC interface. You can find the documentation here:
https://github.com/ethereum/wiki/wiki/JSON-RPC
There's a small library for easily doing this in PHP here, although it is two years old:
https://github.com/btelle/ethereum-php
Comment: tbelle's Ethereum implementation is outdated and not maintained.

You might have a look into  https://github.com/digitaldonkey/ethereum-php

https://ethereum.stackexchange.com/questions/13826/php-library-for-ethereum
Comment: Waht is a "official implementation"?
The recommended Library had hist last Commit in "Commits on Sep 12, 2015". It not maintained, outdated and therefore totally useless.
Answer: After trying some of the php libraries available on Github, I ended publishing my own web3 php library.
Web3-php is a little bit outdated (doesn't support ABIv2) and has problems on transaction signing. And Ethereum-php requires php8 and wasn't an option for me.
Here is what worked for me:
https://github.com/drlecks/Simple-Web3-Php
Answer: As @Jesse Busman said, not PHP library to use web3 API. Also, using JSON-RPC only will limit your app and make it more complicate for you to code what you really want, which is mostly token interaction. Lot of things you can do with web3 that you cant through JSONRPC!
web3.js is what you look for, and I don't recommend PHP  for building ETH Dapp.
Comment: Can you explain why don't recommend PHP or is just a personal opinion? Please justify your recommendation.

web3 js php implementation


How to get Facebook likes count for a Facebook page?

Question: I am making GET request to Facebook graph API like:
https://graph.facebook.com/Yahoo?fields=likes
It is returning the likes count even if I am not logged in.
But for URLs like: https://graph.facebook.com/CaraSutrasPage?fields=likes
I am NOT getting the Facebook likes when I am not logged-in. The reason here is, this Facebook page is age-restricted.
From this question, I tried including the User access_token like:
https://graph.facebook.com/CaraSutrasPage?fields=likes&access_token=CAAGRLGYz...User_access_token
But this works only when that user is logged into developer.facebook.com site. After logged-out it is returning <code>"Error validating access token: This may be because the user logged out or may be due to a system error."</code> message.
I want to get the Facebook likes for a list of Facebook page URLs(e.g. https://www.facebook.com/TheRedheadBedhead and https://www.facebook.com/pages/Sexational/382577001850507?ref=hl) which are stored in database. I have not idea about which are age-restricted and which are not!
Is there any way if I can get the likes count using FQL?
I am looking for a way to get the facebook likes by any method: GET request(e.g. https://graph.facebook.com/CaraSutrasPage?fields=likes), POST request or FQL!
Any help is highly appreciated!
Answer: You can simply hit the url and pass your pageId and token
<code> https://graph.facebook.com/<YOUR_PAGE_NAME>/?fields=fan_count&access_token=<YOUR_ACCESS_TOKEN>
</code>
It will return a Json object.


What credibility indicators can be used for a new web app?

Question: I understand that when you have an app which you launched an year back or so, its pretty easy to get testimonials from your users which then works as 'credibility indicators' when published on your website. They work in your favor and convert more visitors into your customers. But I want to know if there are any credibility indicators which you can use with a new web app or website?
Answer: Supposedly trustmarks actually do have some influence on consumer confidence. Though all the whitepapers I've seen that claim this are also published by VeriSign and similar trustmark vendors. However, if you trust these claims, then a VeriSign, BBB, as well as a trustmark from your SSL vendor (perhaps an EV SSL cert) might help establish confidence.
Though to be honest, I've seen a lot of really sketchy sites that bear a ton of trustmarks, so I don't put much stock in them, especially as many dedicated trustmark vendors don't actually vet their trustmark recipients, and there's no way for consumers to report trustmark wearers for bad business practices. However, with BBB and VeriSign, there is at least the brand recognition factor.
Which brings me to the next method: brand recognition. If you can get some major clients early on, then you can display them prominently on your front page. This was done by Haulix when digital promos was still a very new thing. They had the major labels signed onto the service from the get go, which gave indie labels the confidence that reviewers and other press contacts would actually use the service if they signed up for it.
Likewise, if the app is developed by a well-known software publisher, or made by the same people as an established app, then that would be another way to bank on brand recognition.
Alternatively, you could send invites to notable internet personas and web press so that you can get their endorsements to put on the homepage. There are many news sites out there that cover web apps and new web startups, and an endorsement from them can go a long way for many different reasons.
Lastly, your app should be well designed. There are a lot of apps out there that might be quite useful and a great value, but they don't get much use simply because the app looks crappy and amateurish next to professionally designed sites like FourSquare, Twitter, Amazon, etc. And a poor design isn't just a lack of marketing sense, it can be indicative of a true lack of professionalism and competence. Many such sites have poor UX design and potentially even more serious problems. I mean, it's a bit like seeing a restaurant or store that has a sign made from spray-painted cardboard. If they can't afford professional signage, then who knows what other corners they're also cutting.
Even though many sites like Google, Amazon, Craigslist, etc. have succeeded despite their poor initial designs, those days are long gone. There are plenty of professional web app developers out there today like 37signals who know how to deliver, not just useful features, but a polished, well-designed user experience. So if your web app is poorly designed, users will just move on to a product from a more professional web studio.
Answer:
Get quotes from early adopters and beta users. Journalists, bloggers, beta users, and well-known individuals in the field your app targets are good sources of testimonials; they don't have to come from long-term users.
Mine twitter to see what people are saying about your app. Pull the best quotes onto your homepage under a header such as "What people say about X" or "Read the buzz".
Get feedback from users as early as possible. Even if a service is new, you can collect feedback early on and use it to build credibility. Be sure to feature customer feedback that shows the benefits for using your service. e.g. "Service X saves me 20 hours a week!" is probably better than blanket statements like "Service X is great!"
Use statistics as social proof as soon as they become substantial. 37signals-style "Millions of people use Service X to manage their sock collection" builds trust and credibility. You could substitute "millions" for "thousands" as soon as you reach two thousand users.


Did Clark's (Kal El's) glasses increase the power of his heat vision?

Question: In Superman II Lois jumps into the Niagara River to test her theory that Clark is actually Superman. Clark uses heat vision to break a branch off of a tree in hopes that Lois can use it as a life saving flotation device. Did Clark's thick, thick lenses provide assistance to his heat vision? If not, how did his glasses not get melted or destroyed? They were not a part of his original uniform.
Comment: Understand question is about the movie.  Just offering some general info and I did qualify the comment with "doesn't help with the movie".  It was a comment, not an 'answer'.
Comment: In the original comics, I believe the lenses in the glasses were made from a window of the ship that brought Kal-El to Earth.  Doesn't help with the movie because that ship had no such window :)
Comment: My question is about the movie.
Comment: Oh got it. Didn't mean to sound rude. There is a "comic book guy" lurking around here who seems to think that parts in the script which were left out of the film are relevant.
Comment: Depending on what the heat ray vision is exactly, it may not affect glass at all while still being able to cut trees. (Just like sunlight shining into your window will warm up things inside, but it won't warm the window panes.)
Answer: It's just a plot hole and there's no real explanation for it, other than one someone could just make up (ie super-focusing micro-heat vision). Something similar happened in the first episode of Lois and Clark. It's best to just ignore it.
And the beauty is, you can if you watch Superman II: The Richard Donner Cut. It's a 2006 recut of Superman II by the original director, who was replaced during filming of the second movie. In this version there is now a similar themed scene in the Daily Planet building at the start of the movie, which covers much of the same ground, so much of the Niagara Falls stuff has been chopped out. It's worth a look, if you haven't seen it already.


If I charge my mobile from different charger what happens?

Question: My charger is lost so I am using a charger with an output of 5.5v and 0.6A. My real charger  gives an output of 5V and 0.7A. Will the other charger damage my phone?
Comment: That question does not raise the concern about the extra half Volt.
Answer: No, it will not damage your phone. As long as it's a micro USB charger, it will be fine.
5.5V is fine, I've had success with 6 Volts from a homemade charger, and you won't meet voltages higher than 5.5V on a micro USB charger anyway. Extra Volts are dangerous, so it's good to be cautious but 5.5V will not do any harm.
The current rating (Amperes, A) does not count; if it's too low, the phone may charge slowly or not at all, but higher rated chargers will not do harm.
Comment: So as a higher water pressure would tear your faucet off the wall, so would a higher voltage damage your phone; but plus half a Volt is not high enough to do harm. Extra amperes don't matter as it's a maximum they write; the actual current is determined by the phone (or how much it opens the tap). If it needs too much, it can overexcercise the charger, making it overheat, but the phone won't be damaged.
Comment: Hi, this is something I know nearly **nothing** about, and I was curious. Would a higher amperage not burn it out if it is too high, or is it regulated by the device? I'm just thinking out loud, the micro USB on Samsung devices looks like it was soldered in by a blind cat and I've seen devices burn out. So, the device being ok, the Volts/Amps don't matter?
Comment: Think of voltage as the force pushing the current in the wire. An extra half a Volt doesn't matter, the phone has an internal regulator which can cope with little higher voltages. Don't go much higher, though, (like 9V) as it can damage your phone.
Comment: Amperes mean how much current is flowing. The ampere rating written on your charger means how much current it can supply. Think of it as the tapwater: the force pushing the water out is constant, but if you only open the tap a little, only a little water flows. But if you keep opening the tap more, you'll hit a point where the water flow will not increase; this is the charger's amperage, or current rating. The more Amperes a charger can provide, the better - a phone will only draw as much current as it needs.
Comment: If anything, a too low current rating can be harmful, not for the phone but for the charger - it can overheat and malfunction.
Comment: Excellent, many thanks for that! Very interesting to read, and something that is worth knowing. Much appreciated.


Publishing from IDE removes wildcard mapping in IIS7 in classic mode

Question: I have an ASP.Net app that I deploy to a IIS 7.0 server in classic mode.
I use the publish feature from the Visual Studio IDE. Every time
I perform a publish, the wild card mapping is removed. Anyone know
how to prevent this?
Thanks!
Answer: The wildcard mapping is stored in the application's web.config. You could create the mapping and then copy the section from the system.webServer->handlers section into your dev web.config.
Or you could use a Web.Deploy project to setup the web.config exactly as it needs to be for deployments.


CakePHP Observe field for validation check(already exists)

Question:
i have already user observe field in cakephp 1.3 Now i want to do the same thing in cakephp 2.0
I have one form.there is a one field named email. When user insert email. onblur there is a popup one message that displays "email already exists" or "right"

for that i have write below code in my projects. the below code is my add file code
<code><?php $options = array('url' => array( 'controller' => 'users', 'action' => 'is_exist'), 'update' => 'email_exist');
        echo $this->ajax->observeField('UserEmailId',array('url' => array( 'controller' => 'users', 'action' => 'is_exist'), 'update' => 'email_exists'));  ?>
</code>
In my controller i have created one function like
<code> public function is_exist($id = null)
    {
    $result = "yes";
    $this->set('existdata',$result);
    }
</code>
i have also created is_exists.ctp fiel in view/uers.
 i dont know  why its not working.
i did the same thing in Cakephp 1.3 and its working file but not in cakephp 2.0
can anyone tell me how i implement this ?
thanks in advance
Answer: because ajax helper is not supported in cakephp 2.
you need to learn how to implement it using the js helper
check this link : js helper


How can I know why I am blocked from doing questions in the wp development stack?

Question: How can I know why I am blocked from doing questions in the wordpress development stack?
When I have a question I make one, what is wrong with that? All the questions are just questions I have? So I do not understand the why and for me makes no sense.
Have read that I will need to improve all my questions that I had made in the past. But I dont see nothing to improve, they are reasonable questions that I had. MAKES NO SENSE!!!!
Answer: Almost 40% of your questions are deleted or closed. You've asked some off-topic questions (syntax errors, WooCommerce, Elementor), and there is rarely any debug information or other visible research effort. You can do better!
The automatic question ban kicks in when too many of your questions are deleted or closed, and when there are too many downvotes from different users. The exact details are a secret.
We have a very help page about this topic that explains how to fix this issue.
Please do not create new accounts to circumvent the question ban. This would be a serious violation of our rules, and we'd have to block your main account.
Comment: Thanks for the reply, I will try to do better. but the questions are closed once the answer has been achieved. Honestly I feel sad for this. Once that I try to answer 10 times more than the doubts I have, and 30% of my questions I had been the one to find the solution that works for me of course. I thank to everyone that I had help me. I had review the 23 questions I posted and I cannot agree with this. happy coding to everyone.
Comment: I am giving this the right answer because I feel that I got the right feedback...


Power Query Windows authentication with Odata feed

Question: I am currently trying to find a way for a customer to connect with Power Query (plugin for Excel) to access their published Odata-feed (which is hosted by Microsoft NAV 2013 R2).
For security reasons the NAV server is set to only accept Windows as an credential type. This means that the current user credentials on the client is passed on to the webservice.
The problem: The users of the system is often off site and working on another domain with a VPN connection to the NAV-environment. With that said Power Query does not pass the "correct" AD-information to the published Odata-feed which means that the user is not authorized.
I am looking for a way to change which AD-credentials that are sent thru Power Query and then to the Odata webservice.
The users have no problem typing in the webservice adress in a web browser and type in the Windows credentials when prompted and access the feed. But in Power Query there is no option for typing in custom Windows Credentials when refreshing the data.
I've tried with WebAPIKey and Basic authentication. But since the NAV-server/Webservice is set to only accept Windows authentication I'm in the dark..
Any thoughts?
Answer: I got this answer from Curt Hagenlocher (Moderator on Technet)

I'm afraid this isn't something we currently support, though we have
  considered implementing it. We do loosely track feature requests and
  use them to prioritize future work.

(https://social.technet.microsoft.com/Forums/en-US/03c529ba-5f20-4bc1-84de-35cc91e7c1a6/power-query-custom-windows-credentials-authentication-with-odata-feeds?forum=powerquery)


Applications of fakeroot and chroot

Question: Why are there two utilities chroot and fakeroot when both can fake a privileged access to the user?
Answer: chroot actually does something very different from fakeroot. it stands for "change root" and means you can run a process which has the '/' directory mapped to something different than the system. In most cases, this is an operating system installed on a different drive or partition. Within that chroot environment, the root privileges are actually real, in fact chroot can only be accessed by privileged processes. Fakeroot just gives a process the illusion of root access when in reality all files created by it will just belong to the original user.
Answer: Only fakeroot will "fake priviledged access to the user".
Invoking chroot can enable some user to run commands with regards to some root (/) directory tree different from the one currently in use on the system.
Let's say that the desired root directory stands in /mnt then, in the chrooted env, firing /foo/bar will in fact launch /mnt/foo/bar and have bar behaving as if /mnt was the real root directory.
BUT, of course, if the user does not get appropriate access rights to /mnt /mnt/foo and /mnt/foo/bar then… it won't just make it.
User does not automagically become root (user) or even a fake root user. Only the root base directory is changed.
BTW chroot utility comes with the coreutils package which is necessarily part of the most basic linux distribution. You generally need it when installing a new system from within another one.
fakeroot will create an environment in which the user can act as if it were root regarding file manipulations.
By "fake", you should understand that this will only be valid within that environment. For any other user, for the system itself… and for yourself after exiting, nothing will have changed. Let's consider some example inspired from the man page :
$  whoami
me
$ fakeroot /bin/bash
#  whoami
root
# ls -ld / (note that this is the original (real) root directory)
drwxr-xr-x  20 root     root         1024 Jun 17 21:50 /
# chown me:users /
# chmod a+w /
# ls -ld /
drwxrwxrwx  20 me    users        1024 Jun 17 21:50 /
# exit
$ ls -ld /
drwxr-xr-x  20 root     root         1024 Jun 17 21:50 /

BTW contrarily to chroot, fakeroot comes as part of a package you'll need to install specifically. You generally need it when archiving files to be deployed on other systems with user id 0.

Applications of fakeroot and chroot


Messy top layer with PETG filament?

Question: I'm having issues getting PETG to print nicely. I have encountered pretty much every issue because when I fix one thing another issue pops up. I see people saying that you should "just copy your PLA settings", but that definitely did not work for me, with issues from bed adhesion, stringing, globbing, and especially issues with the top layers. At the moment I am getting very decent quality prints from PETG, however the one issue that remains is the top of the print.
Infill looks fine, it is printing fast, so that is where I would expect the filament to glob to the extruder. But that happens on the very first top layer. The printer goes over the honeycomb, and the filament gets oozy and starts forming in globs on the edge of each inner wall. This takes a few layers to print over, and even after 5 layers at 0.25 mm layer height it has holes.

Software: I am using Slic3r PE 1.41.2, on Repetier Host 2.1.3.
Printer: Wanhao DI3 or Monoprice Maker Select Plus.
Filament: Amazon Basics branded Navy Blue PETG.
Settings:

40 mm/s print speed,
0.2 mm layer height,
70 °C heat bed,
235 °C hot end,
15 % honeycomb infill,
20 % - 50 % automatic fan speed.

I would like to solve this without increasing infill percentage because the parts are already quite dense with 15 % honeycomb and I don't want to waste material and time.
Comment: Welcome to 3DPrinting.SE!
Answer: Five top layers should normally be more than enough to create a seamless top layer.
Indeed, PETG prints a little differently than PLA. It requires a higher hot end temperature, less part cooling (to improve sticking to previous layers), a higher build plate temperature and usually care in choosing the right initial layer height. Once the printer  needs to create the top surface layers, too much temperature, too less cooling and too low of an infill percentage can cause the top bridging over the infill to fail. Your settings seem to be fine except for the low percentage of infill, 15% is very low.
Other possible causes could be under-extrusion and too fast printing, but in this case the low infill percentage is probably the main reason. To get a better top layer you could first try to increase the infill percentage. If you go to 20 or 30 % infill, you would only marginally "waste" filament. More filament and time is wasted when whole prints fail as of a bad top layer.
Comment: 15% infill usually works fine for every plastic type, is it really too low for PETG? I am using Slic3r's Honeycomb infill, and each cell (approximated as a circle) is about 6 millimeters in diameter. PETG can't bridge 6 millimeters?
Comment: @spikespaz Usually this should not be a problem, but clearly one of the parameters you use is causing this to happen. 6 mm should be doable. Unfortunately, your settings seem okay, similar to what I use. Only I always have higher infill.
Answer: I have been having the same issue with PETG when printing but I have found that if I slow the printer down to 50% speed that left me with a perfect top layer. I have a 20% infill with 4 top layers and at 50% speed I am printing at roughly 32mm/m. I am sure that will help give you better top layers.
Answer: If you're using Slic3r, check what line widths it's using. By default it extrudes with dynamic widths up to considerably wider than the nozzle size. PETG is only borderline-printable at 40 mm/s with 0.4 mm line width and 0.2 mm layer height. If Slic3r increased some of the line widths to 0.55 mm or so like it typically does, you're likely getting underextrusion, and need to either go slower, constraint the line width narrower, use thinner layers, or find some way to increase the amount of material you can push through the nozzle per unit time (maybe going hotter or using a higher-power hotend).

Messy top layer with PETG filament?


Are there any kittens to attack for no apparent reason?

Question: I recently got my Goobbue Sproutling and the description says,  "Has been known to attack kittens for no apparent reason". Now I'm wondering: are there any kittens in FFXIV for my Goobbue to attack? Or is this just flavour text?
Answer: Although there are a few kittens in the game -- the Cait Sith Doll minion, for example, as well as a significant portion of the playerbase -- they can all rest easy for now, because the Goobbue Sproutling doesn't appear to have any special behavior around kittens, barring any exceptionally well-hidden easter eggs. While a similar description also appears in the German flavor text, the game's other two languages don't make any mention of kittens at all.
If you're curious, the French flavor text roughly reads "be careful not to get your fingers bitten," and the Japanese is something along the lines of "word is that the cost of feeding him is nothing to sneeze at."
Comment: Ahh it is a shame, I figured if they add that you can do /sit next to a bench, and actually sit on the bench. They would add something like this aswell. Thanks :)


Can I use shortage instead of "material in short supply"

Question: Can I use "shortage" instead of "material in short supply".
For example, "The other two shortages will be pulled in next Monday", I mean the other two items in short supply now will arrive next Monday.
Thanks in advance.
Comment: I have not come across the expression **pulled in** in that context although I've seen frequent reference to **making up** a shortage.
Comment: Can you provide more context? As of now, your sentence looks incomplete. When you use "shortage", it isn't clear what is in shortage.
Answer: When you say "shortage" you are depending on the context to clarify what you mean.
Generally a shortage is a lack of something, not the thing that is lacking. Since there is a simple alternative "items in short supply", I would use that alternative.
Comment: Thanks. Do you have other way of indicating the thing lacking?