Can a non virgin have a church wedding?

Question: A friend of mine who is a Christian made a mistake and lost her virginity before marriage.  According to the rules of the Assemblies of God denomination, can she still have a church wedding?
Comment: Which 'church' are you enquiring about ? The question needs to be scoped as different Christian groups will view this matter differently. Some do not treat marriage as a 'sacrament', for example. Some would argue that a woman had 'married' by giving herself. Paul speaks to 'virgins' and 'widows' - none other. Separated women he calls 'unmarried'.
Comment: Then an edit would be appropriate @Nina so that contributors may be  aware of it. I have  added the appropriate tags for you.
Comment: Assemblies of God church. It is a pentecostal church
Comment: @Nina Welcome to C.SE.  I edited the question as an example for you since when different denominations have different answer, we require the questions to clearly narrow the scope so answers can be objective.
Answer: Can a non virgin have a church wedding?
The short answer is yes.
Although virginity before marriage is highly recommended and it is encouraged by the Scriptures, it is not an absolute necessity.
Even widows may get remarried according to St. Paul.

To the unmarried and the widows I say that it is good for them to remain single, as I am. But if they cannot exercise self-control, they should marry. For it is better to marry than to burn with passion. - 1 Corinthians 7:8-9

But because of the temptation to sexual immorality, each man should have his own wife and each woman her own husband. - 1 Corinthians 7:2

But if they cannot exercise self-control, they should marry. For it is better to marry than to burn with passion. - 1 Corinthians 7:9

I personally do not know of any denomination that would refuse a Church wedding based simply on the fact that one or the other (or perhaps both) are not virgins. There may exist one, but I do not know of any such denomination.
Comment: Certainly she should go to confession first.  (I would recommend this before marriage anyway!)  In any denomination that considers marriage a sacrament, you should want to come to the altar in a state of friendship with God so that you can receive the grace of that sacrament.
Comment: @workerjoe True for those Churches that have that opportunity as part of their sacramental life.
Comment: virginity before marriage is not highly encouraged, it is instructed and required on both sides. Both the man and woman.
Answer: This is such a great Question.
I'm Pentecostal and so are our kids.
Anyways my kid Fornicated and they have a kid on the way. We told them to get married because it was the right thing to do. We called the church to see if they could have a wedding there and the 2nd in-command pastor told us that what he is about to say came from the main pastor.
They said that if they want a wedding at the church it would have to be private in the pastor's office or if they wanted a big wedding it would have to be in a different venue but the main pastor could officiate it. They said since they fornicated that they broke a sacred vow that God will deal with them as the church has a standing rule of not marrying people in this situation for about 30 years.
Wife is very upset and we tried to plead our case. It's still going through the process and will try to figure out what will happen.
I will update this answer as we go along
So as to answer your question I think it depends on the church's rules
Answer: As the answers show, there are (small) differences between denominations.
I have met people, Christians, most definitely not Catholics, who were convinced that by having intercourse, you are married. So their point of view was that at the moment one looses ones virginity, one is married. And the consequence would logically be that the church marriage, of not with the one you had your first intercourse with, would be adulterous. Interestingly enough, they didn't draw that conclusion.
But I think most denominations I know of, do not teach that virginity is an absolute prerequisite for marriage. It may be preferable for the first marriage, but as in most (all?) denominations widows can remarry, virginity can hardly be demanded. That does not mean that the circumstances of that first intercourse can't be a problem. The other answers explain this in enough detail I think, so I will not be repeating that. Only some specific catholic details: confession should me done with a priest in our church. Marriage itself is a sacrament administered by the man and woman, with a priest or a deacon as witness on behalf of the Church. Entering marriage in a state of (mortal) sin doesn't nullify the marriage, but it is not a very good start. No priest or deacon will, or at least should, assist in a marriage if the state of grave/mortal sin is public, but he can never make it public by not allowing the marriage.
Comment: While there may be occasional people who believe this, I've never encountered an actual Christian group who believed this. Since the group will be deciding who gets married, they are the ones who count. Do you have an example?
Comment: As I said: "I have met people, Christians…". I did not say they represented any kind of group or official teaching of any kind. So what example are you asking for? I don't think the names of individuals who expressed this belief are of any use?
Comment: As I said, individual Christians don't make marriage rules so their views aren't relevant to the question.
Answer: We first of all need to understand that chastity is a requirement. Part of holiness is keeping your virginity till marriage. And so it is actually a sin to have sex before marriage.

9 Or do you not know that the unrighteous[a] will not inherit the
kingdom of God? Do not be deceived: neither the sexually immoral, nor
idolaters, nor adulterers, nor men who practice homosexuality,[b] 10
nor thieves, nor the greedy, nor drunkards, nor revilers, nor
swindlers will inherit the kingdom of God. 1 Corinthians 6: 9-10 ESV

And not just sexual immorality but every other sin is stopping us from being with Jesus in eternity. And this has been since Adam and Eve. However, this is just why Jesus died for us.

8 But God demonstrates his own love for us in this: While we were
still sinners, Christ died for us. Romans 5:8 NIV

So Christ died for us that what is sin may still be sin but imputed on Him so we may now be forgiven and have a chance at doing it right. We have all sinned and that is why Jesus died for us. If I am to list my sins down, stackExchange will run out of disk space. So the short answer then becomes; Yes! a non-virgin can get married in a church but under the following conditions:

9If we [freely] admit that we have sinned and confess our sins, He is
faithful and just [true to His own nature and promises], and will
forgive our sins and cleanse us continually from all unrighteousness
[our wrongdoing, everything not in conformity with His will and
purpose]. 10If we say that we have not sinned [refusing to admit acts
of sin], we make Him [out to be] a liar [by contradicting Him] and His
word is not in us. 1 John 1:9-10

When we have admitted our wrongs and confessed to Him, and then accepted Him to be Lord and Saviour of our lives, then our sins are forgiven and so it is ok to bring your marriage before God in church or even at home with a priest. However, if we do not do this and we go on acting it is ok, then we reject His forgiveness and we are still in sin and so will not even make sense to go to church.
My question then becomes, why does she want to get married in church? If its because she is a Christian and has accepted Jesus in her life and confessed her sins (NOT NECESSARILY TO A PRIEST) but to God and allowed the Holy Spirit to lead her then Hallelujah if not and its just for the fun of it, I do not know.

11 And such were some of you. But you were washed, you were
sanctified, you were justified in the name of the Lord Jesus Christ
and by the Spirit of our God. 1 Corinthians 6: 11 ESV

I hope this helps.
Comment: Yes she is a Christian saved by grace through faith. She has given her heart to the Lord Jesus. Can she wear a veil and cover her face?
Comment: Honestly, this could have either answers but I would say yes. If Christ forgives us, He really does and we get to start afresh as though nothing ever happened.

Can a non virgin have a church wedding?


Is it possible to limit export feature class in ArcSDE to only some users?

Question: I'm trying to manage user and their privileges in ArcSDE and sql server 2012. I can privilege the select and edit a layer for users. I can use just two privileges but i want to permit export feature class capability for some users.Is it possible to permit and revoke export feature class for users ?
Comment: This is often asked, and simply not possible. Any user with SELECT access can export data in a multitude of ways.
Answer: It is possible but not easy. you should write custom ArcObject code to disable any tool or command that exports feature data. And off course you should manage users with a custom user manager application to set their permissions (enable/disable feature export)
Comment: And you'll need to eliminate access to the database client from anything but ArcGIS, and to prevent the user from downloading any application which could access the database directly,...  In fact, you *can't* prevent a determined user with SELECT permission from accessing the database rows and writing them to ASCII. You can strip all access except though proxies, but then users are unlikely to be able to accomplish necessary tasks, and still an experienced user could use the image service for heads-up digitizing.
Comment: This will **not** prevent export, just make it slightly more difficult.
Comment: Off course Many other things must be disabled too, like, Python window, model builder, search dockable window. But it is possible to prevent the export. Vince, I've done this before!
Comment: @FaridCher I don't want to use Arcobject solution.Thanks anayway


Why should one perform an extraction with multiple small portions of solvent as opposed to one large portion?

Question: I'm performing a liquid-liquid extraction on a 1 l water sample for GC analysis. The procedure calls for three extractions with 50 ml of dichloromethane. Would one extraction with 150 ml produce a different result?
Comment: Most definitely yes.  Qualitatively, you can perform a casual experiment to observe the difference the next time you wash your hands in a bathroom that offers paper towels for drying.  Compare how dry your hands get when you (a) pull three paper towels off all at once and dry your hands with them all at the same time; versus (b) pulling three paper towels, one at a time, tossing each paper towel after it feels like it's not getting your hands any drier.  (b) will get your hands dry much more effectively.
Answer: The important thing is the distribution ratio (for the extraction of a metal) and the partition coefficent for the extraction of a given chemical species. This can be used for a first approximation calculation.
The distribution ratio is the total metal concentration in the organic phase (grams of metal per litre) divided by the total metal concentration in the aqueous phase.
If we consider a batchwise extraction where a litre of water bearing x mg of a metal is extracted with an organic solvent. Assume that the distribution ratio is 2. We can do the calculation for the extraction.
The phase ratio (ratio of the volumes of the two phases) is 1, call this theta.
Theta D / (1 + (Theta D)) = the fraction extracted in each stage.
If D is 2, and theta is 1 then we will extract 66 % of the metal.
As an alternative, if we use one litre of water and extract this with 0.5 L of organic phase, then with D = 2 and Theta = 0.5 then we will extract 50 % of the metal.
If we repeat the extraction with another 0.5 L of solvent then we will recover 50 % of the remaining 50 % of the metal. Thus we will have recovered in total 75 % of the metal.
If instead we were to extract the 1 L of water four times with 0.25 L of water then in the first extraction we would leave 66 % of the metal in the lower phase. The easy way of working out the amount left in the aqueous later after n extraction stages with the same D and theta valve is to use
{1 - ( D Theta / {1 + (D Theta)})}^n = fraction left in raffinate. In solvent extraction raffinate is the term for the aqueous layer after an extraction has occured.
This gives me about 20 % left in the aqueous phase after four extractions with 0.25 L of solvent.
It is important to understand that the solubility of the substance is not what you should consider it is the distribution ratio or the partition coefficent which is needed.
If you were to take a dilute solution of DEHPA (150 mM) in aliphatic kerosene and to shake this with 0.1 nitric acid containing a small amount of Fe-55 with no stable iron as iron(III) then you might get a D value of 100 for arguments sake.
Now the organic phase can only extract 50 mM of iron per litre as to extract one iron atom three DEHPA molecules are needed. If we were to repeat the extraction experiment with a solution of 56 grams of iron per litre (roughly 1 moles per litre of iron) spiked with a little Fe-55 then we would measure a far lower distribution ratio.
This is due to loading of the organic phase.
Equally when you extract a large amount of an organic substance into an organic solvent the solvent properties of the organic layer at the end will be different to those of the pure solvent.
For example if I have 1 litre of water saturated with hexanol with 500 ml of water saturated hexanol floating on the top. Then if I was to add 500 ml of ether and then shake it. I would have a different Kd for hexanol to that which I would have if I was to shake a dilute solution of hexanol in water with ether.
I hold the view that the formula used above for the system with a D value of 2 will only hold perfectly true when the concentration of the metal is zero. This is why radioactive tracers are so useful for academic solvent extraction experiments. This is becuase they allow the measurement of distribution ratios with a zero metal concentration. The concentration in moles per litre of a 1 GBq per litre solution of Fe-55 will be very small.
The half life of Fe-55 is about 2.7 years, thus I have calculated that this very radioactive stock solution will contain 205 nanomoles of iron if the only iron atoms present are Fe-55. The best way to make the iron-55 would be to bombard managense with protons with a cyclotron and then to separate the iron from the manganese by solvent extraction or some other separation method.
I would in a lab expect to be able to run a solvent extraction experiment with only 700 Bq of Fe-55. If we assume that I was to shake 700 microlitres of aqueous phase with 700 microlitres of the organic phase. I would then be able to sample 200 microlitres of the two layers with a pipette.
If we assume that the highest distribution ratio I was to measure was 100 then I would expect that at the end of the shaking that the aqueous layer would contain 10 Bq per ml. If I was to sample 200 microlitres and to put this into a LSC vial and then to count it. Assuming that 100 % of radioactive decays will result in a count in the LSC machine then I would in one minute get 120 counts. If I was to count until I had 10000 counts (1 % error due to count number) I would have to wait about 83 minutes.
For a D value of 10 I would be able get 10000 counts in less than ten minutes for the least radioactive liquid phase. Thus it should be clear that with a radiotracer it is possible to measure the distribution ratio with less than 1 nanomole per litre of metal present.
Comment: By the way, you can use MathJaX for equations - it has mostly the same syntax as LaTeX, if you are familiar with that. see e.g. https://chemistry.meta.stackexchange.com/questions/86/how-can-i-format-math-chemistry-expressions-here


Can you play multiple cards together of the same number but different colors?

Question: During an Uno game, can one player put multiple cards of the same number but not the same color on top of each other, with the first card the same as the previous one in the Discard Stack?
Answer: You may only play a single card each turn and note the rules mention playing "a card" not multiple.
Rules

You have to match either by the number, color, or the symbol/Action. For instance, if the Discard Pile has a red card that is an 8 you have to place either a red card or a card with an 8 on it. You can also play a Wild card (which can alter current color in play).
Answer: What you are referring to is a common house rule in Uno, that you can play multiple cards of the same value in a single play.  This is not in the official rules of Uno, and as such, there is no canonical answer other than "this is not allowed".  However, having played under the house rule, it usually goes like this:

You can play multiple cards of the same value as a single play, even if they are different values.
The bottom card must match the value or color of the previous top of the stack, but beyond that, you choose the order of the other cards that you play.
If the cards are numeric, there is no effect other than you having played multiple cards.
If the cards are a special effect, that effect is applied multiple times

Draw 2 or Draw 4: the value adds together, so three Draw 2's means draw 6 cards
Skip: skip a number of players equal to the number of skips played
Reverse: reverse a number of times equal to the reverses played; this equates to no effect with an even number of reverses and a regular reverse effect with an odd number

You can't go out on a play of multiple cards.  You must keep one of them in hand, declare "Uno", and then try to play it next turn.

This house rule has the advantage of allowing players who have gotten many extra cards to have a better chance of coming back (as the more cards you have, the more you will likely have with the same number).
I have typically seen this house rule played with the additional rule:

If someone plays Draw 2s or Draw 4s against you, you can add any number of Draw X card of the same type to pass it on to then next player, with your cards adding to the total needing to be drawn (ex. someone plays two Draw 2s against you; you can play one Draw 2 to make the next player draw 6 cards).


What's the proc chance of the Savage Strike perk?

Question: In the One-handed perk constellation (skill tree), there's a perk called "Savage Strike". The description claims that "Standing power attacks do 25% bonus damage with a chance to decapitate your enemies." What is the probably of to decapitate your enemies?
Answer: According to IGN it is 10%
Tho the 10% chance sounds about right,here is where it gets confusing,ingame you can use console command "show/set decapitationchance" which shows you the value of 40%,to be even more confusing the 40% chance is the same whether you are lvl 1 or level 60 with savage strike perk.
Which means that perk savage strike and finishing move decapitation work independently.Which does make some sense since savage strike indicates that it must be Standing power attack to trigger decapitation,where in contrary people say that they managed to get decapitation while sneaking,crouching,moving,without power attack...
Telling you where exactly those 10% fit in to the finishing moves would be just me guessing.
You should read more about finishing moves and see for yourself.


Can the Incredible Hulk die?

Question: In this question some users pointed out that the Hulk cannot age or ages really slow in relationship with normal people, which makes him an immortal.
But my question is this: Can he die in a battle?
Answer: The simple answer is yes, but it varies how it is possible.
In the one-shot comic "Hulk: The End" written by Peter David, Hulk is almost invincible. He survives a nuclear holocaust when no one else does. Although, Bruce Banner is not invincible. He dies and hulk realizes he cannot transform without dying also. From the synopsis:

Suffering a painful heart attack, Banner realizes how much his punishment resembles that of Prometheus, the Last Titan; condemned to stay forever alive even while animals devour him, speculating that the Hulk's suffering is Earth punishing him for humanity's sins as the embodiment of the nuclear wars that destroyed Earth. As he dies, the Hulk's persona arises in his mind. [...]
The next morning, the Hulk somberly sits outside the cave, musing in his inner monologue: "Banner is gone...got rid of him last night." As he remembers the confrontation, he realizes that if he were ever to change back to Banner, he would die also.

In the Lou Ferrigno version of Hulk, there was a TV movie called The Death of the Incredible Hulk. Hulk falls from a exploding plane and dies on the ground. Although in true comic style, "there was talk of another Incredible Hulk television movie which would resurrect the character." Unfortunately, Bill Bixby (who portrayed Bruce Banner) dies before that ever happened.
In the comics Tales to Astonish #90 & 91, the Abomination is created and kills Hulk. He is revived shortly after though.

In the Old Man Logan comic series, Hulk kills and eats Logan. "Logan recuperates within Banner's stomach and bursts out, killing him." See below:

In Thor #73 (The Reigning Part 5), Thor kills the Hulk and others. Although, I believe at the end of The Reigning story arc Thor turns back time. This gallery has several pages from that issue, such as the one below. Thor also snapped Hulk's neck in a What If? issue that I couldn't find.

Other characters have supposedly killed the Hulk, such as Deadpool, Red Hulk (Rulk) and Galactus. But they were all in "what if?" type comics, and I couldn't find solid details online. I found evidence that Hulk killed Red Hulk (not the opposite), but this stands to reason if one hulk can die, the Hulk could die.

More recently, Hulk was killed by Hank Pym in What If...? Season 1, Episode 3 by entering his body with his Ant-Man suit and increasing Hulk's cells using pym particles until he exploded.
Answer: In The Avengers, Banner said that he had tried to kill himself, but it didn't work.

In case you needed to kill me, but you can't! I know! I tried!... I got low. I didn't see an end, so I put a bullet in my mouth... and the other guy spit it out! So I moved on. I focused on helping other people. I was good, until you dragged me back into this freak show and put everyone here at risk! [Bruce Banner in The Avengers]

There are many theories on how you could possibly kill him, such as ripping out his heart or decapitation, or he could be killed by another super being like in a few of the comics. Other than that, though, I have found no evidence that Bruce Banner/The Hulk can die.
Comment: I'm sure he could not survive being launched into the sun or going through a black hole.
Comment: @Jason: You should look at Nullbreaker's answer, Hulk survived a black hole.
Comment: @DrakeSAN I hear you on the Lore comic evidence but sometimes don't you want to say "Hey, that Lore is just dumb."? That "black hole" looks ridiculous like a tornado. A modern sci-fi comic would not depict a black hole like that as nearing a black hole results in an exponential gravitational difference between atoms which turns everything into string cheese, even Hulk, as he's made of atoms too, Lore aside. I just blasphemed but in this case, I have to.
Comment: Depending on how is written. The Hulk has a regeneration rate even greater than Logan. He should be able to regenerate from a single cell.
Answer: He can die but he's awfully difficult to kill. Brute strength doesn't work, at least it hasn't for many, many years. Certain forms of magic can kill him. During World War Hulk someone used a wishing machine to kill hill but he was immediately brought back to life. Zeus turned off his healing factor and his ability to get stronger and nearly beat him to death. Red Hulk removed his gamma energy and reverted him to Banner. That also happed in Infinity 6 though the effects were temporary and I was under the impression Banner wasn't attacked because he would revert back to Hulk.
Hulk survivng a black hole :

Also nuclear explosions are said to be hotter than the sun and Gladiators heat vision is said to be hotter than the core of a star, Hulk has survived both.
Answer: I have only seen the Avengers Assemble film but based on that it seems like he is pretty much unkillable.  He was able to take a dozen ships concentrating fire on him specifically without seeming to be injured.  He grunted with effort and frustration as he was being overwhelmed but did not seem to show any pain.
Banner was not able to kill himself buy shooting himself in the mouth, the Hulk just spat the bullet out.
However, this does not mean he is invincible.  He could, for example, be thrown into space which would render him useless although alive.  Perhaps he could be frozen etc?  It is not clarified whether Banner could be injured (say blinded) which might render the Hulk less effective.
He can be stopped by a resourceful opponent but in terms of brute force he is a serious presence.
Comment: Could the divebomber give any hints on how the answer could be improved?
Answer: The Hulk can but can't die. In a certain comic Hulk (Bruce Banner) kills Red Hulk (or Rulk). It proves that he can die but only by someone of equal invincibility such as Hulk vs. Rulk. By Avengers' logic he is invincible because Banner shot himself in the mouth and I quote "the other guy spit it out," so unless a godly or equally invincible force is acted upon the Hulk, he is unkillable.
Comment: Hello and welcome to the Stack Exchange. Quick note: "The Hulk can but can't die" is not a good start to an answer. Plus you are mixing canons by referencing the comics and the MCU (which **do** differ). I'd suggest checking out the [Tour](http://scifi.stackexchange.com/tour) to understand how to better ask and answer questions here. It's not a typical conversational forum. Please don't be discouraged, we were all new here at some point.
Comment: Having said that, keep in mind a more detailed answer was already accepted. (Note the green check-mark above for Matt's answer from Dec 13, 2013 at 18:02.)
Answer: Yes he can, but he is almost invincible to anything. Bruce Banner doesn't want to be the Hulk and he can't change it, when he gets mad he transforms. Basically, the Hulk is almost impossible to beat and some say he's immortal but I do believe that Bruce Banner ages when he's not the Hulk so Bruce Banner is not immortal so it's kind of like a Dr. Jeykll and Mr. Hyde.
Answer: I have been reading into this all night after reading the World War Hulk series and wondering if he could die. It was said by one of the super beings that Hulk, even if disintegrated, would reform due to the intense healing. So beheading is out.
The best solution to the Hulk would be someone with the Phoenix powers, preferably Rachel Summers who commanded the power at it's strongest, to simply disintegrate him, absorb his life force and then cast the particles to every end of the universe. That would be the end of Hulk for a very very long time.
Answer: A gamma or nuclear bomb, can kill him if he is right in the place of explosion, that is how Hulk killed the Maestro, who is way more powerful than him. I think the key is in the overpowered abilities, there is a point where too much power is concentrated and a body, even hulk's can not retain it.
Comment: Can you add some references?
Comment: J.Ryder that is no longer the case. During Aaron's run Hulk stood in the heart of a gamma bomb and only lost his hair and eyebrows (Incredible Hulk 6 & 7, 2012). During the Agent of Time arc (Indestructible Hulk 15), Hulk took the same gamma bomb that created him and became the Uberhulk - an incarnation that starts with double the base power of a normal Hulk. During the Marvel Knights arc (issue 4) Banner Hulks up after getting caught in a gigantic gamma bomb then minutes later takes another gamma bomb then reverts back into Banner although at this point his enemy has died so maybe that is why
Comment: Not really. The Hulk has survive Nuclear explosions. You need something more destructive. A trip to the sun might do the trick nicely.
Answer: Thanos beat him in the infinaty gauntlet but thanos had the infinaty gems and was deemed a god, hence him beating most of the marvel universe up at the same time.
Answer: Will edit to add the page, but in Punisher kill the Marvel universe, the Punisher does kill Hulk, with a arrow in the eye.
However, it does not count as it is a "What if" where almost all this alternate universe is affected by a zombie virus.
Comment: The Punisher Kills the Marvel Universe is an out of universe "What If?" type tale and therefore doesn't count.
Comment: @Monty129: I ll edit to make it more clear : )
Answer: Listen guys It really is just impossible to kill the Hulk. No matter what happens whether he gets hit by a gamma bomb or cast to all the ends of the universe one way or another he will still return as the Incredible Hulk.
Comment: Welcome to scifi.stackexchange! Matt's answer provides some canonical evidence that Hulk _can_ die. Do you have any sources, that Matt is wrong and Hulk didn't died then? Btw: Sources are always most welcome around here!
Answer: LOL. I know how the Hulk can die, from my opinion hulk can die easily when he was in human form. Trust me, you will think that what Bruce Banner said in Avenger is true ( that he can't die):

"I put a bullet in my mouth, and the other guy spit it out"

From what I can think of, Bruce Banner still can die, but in a crazy way. What if Bruce Banner in human form exploded his head with a grenade or even with c4? Or he chopped his head off with a katana? I'm pretty sure that these incidences would end with the Hulk's death.
Comment: Do you have any evidence to support this? Purely speculative answers aren't generally accepted on this site.
Comment: Yes please provide your factual evidence references for these fictional fantasy characters.

Can the Incredible Hulk die?


SSD Heat Performance

Question: I'm currently searching for a good boot drive for a desktop.  Is heat an issue for an SSD?
Comment: http://superuser.com/questions/348066/will-an-ssd-help-prevent-laptop-overheating/348076#348076 - for desktop drives, you will see a reduction in heat, but the amount of heat from hard drives is negligible compared to other system components (e.g. CPU, GPU, motherboard).
Answer: SSD's produce less heat than a regular hard drive. So no, not really.
I would say that heat isn't an issue for regular hard drives either. Not in a desktop environment anyway.
Comment: Agreed, although my previous computer had silly hard drives, dual 15.3k rpm scsi disks that definitely increased my cooling load.
Answer: I don't know if SSD produce less heat.  Not according to this:
http://benchmarkreviews.com/index.php?option=com_content&task=view&id=299&Itemid=60&limit=1&limitstart=11
But remember these are 2.5" SSD.  I bet 3.5" HDD would produce more heat.
EDIT
Yup, according to this: http://www.codinghorror.com/blog/archives/000748.html
3.5" HDD produce a lot more heat.  So if you are using SSD on the desktop, you don't even need a fan on it.

SSD Heat Performance


Why would I use Windows Server over Linux?

Question: Is there any specific reason (besides software compatibility) to use Windows Server over Linux? Does it have any innate advantages over Linux as an operating system? I don't see the point of paying extra for Windows Server when I can set up a Linux box for about 75% of the price, if not less. Am I wrong to think this? Is it worth the money?
Comment: This question was asked and closed earlier:  http://serverfault.com/questions/11724
Answer: I try not to comment in 'holy war' discussions, but I'll try to be completely neutral here.
As a sysadmin, I'm a pragmatist. I use whatever works best for what I do. In my infrastructure, I have somewhere between 75-100 Linux machines and two Windows servers. They're the domain controllers for my active directory domain, which I use to authenticate the rest of my Linux machines.
There are directory servers available for Linux that would do what the Windows machines do for me, but it costs the company less to buy licenses and use Active Directory than it would for me to learn to install, configure, and administer those services. There is probably Windows software to perform the other 98% of what I do in Linux, too.
It's cheaper for the company to use what works and what we know, rather than what might work and what we don't know.
Comment: +1 for pragmatism.  Active Directory is a major plus for windows, but if Samba 4 is ever finished and lives up to its billing, I'd certainly look at it if I was creating a new domain.
Comment: I know! I'm really looking forward to v4. It should be a much bigger change from 3-4 than 2-3 was
Answer: Simple answer - for Group Policy.  I don't have sufficient Linux exposure to know if there's an equivalent, but I do know that the sheer wealth of useful information available about Group Policy is hard to beat.
Of course, if you don't need Group Policy you are free to make your own choice.
Comment: +1 for GP ... AD and Group Policy allow for relatively good client security and management.
Comment: Much of the functionality in group policy is not necessary or can be implemented differently on Unix or Linux.  Many of the underlying problems that Group Policy solves are peculiar to Windows because user identity is very heavyweight and permissions are complex on that platform.  Presenting a single system image with uniformly applied security is much easier to do with Unix or Linux.
Comment: I hear this a lot, but nobody ever gives any concrete examples of how you can do similar things in Linux/Unix.  It's always hand waving and "if you don't know, i'm not going to tell you".
Comment: that's because GP is a lot of things - from access perms, to allowed apps, to dhcp settings. You need to say which you want if you require an answer. For a general replacement, look at http://www.centrify.com/directcontrol/grouppolicy.asp
Answer: Choosing between Windows or Linux doesn't depend on the software itself. They both have their strong and weak points. The trick is to determine the most important needs for your site and determine the right solution based upon your needs, not just because some OS has better advantages than some other one.
Linux is free but it's a bit harder to use for inexperienced administrators. It's not that the Linux software is difficult to understand but that there are so many things to choose from. Some of it is great, most of it is good and some is bad.
Windows costs a bit more and leaves you with less choices. Which is a good thing for software. It might sound weird, but less choice makes people more specialized in the few choices they have.
You often hear complains about the bad security of Windows. Unfortunately, security isn't a software issue, it's a people issue. Windows becomes especially weak when people forget to apply updates or forget to install and update a good virus-scanner and firewall. You need those too but there are many Windows administrators who are too lazy or too inexperienced to keep their system secure. It's a problem with Linux administrators too, although Linux administrators tend to be more motivated to do a good job. If the system administrator knows what he's doing, both Windows and Linux will be secure enough for your needs.
Answer:
I don't see the point of paying extra for Windows Server when I can set up a Linux box for about 75% of the price, if not less.

You just answered you're own question. And with Ubuntu server installation wizard/process, you can get it set up practically in a few minutes which should make it 1% of the cost of a windows server.
Comment: But if none of the hardware administrators have any Linux experience, it will take them a lot of time learning to use Linux. In these situations it's simply less expensive to purchase a single Windows licence than to have your administrators go out for some Linux class for a few days.
The costs of a server are small compared to the required man-hours. But once you have an experienced Linux administrator, the costs should go down again...
Answer: When your choice of OS is not dictated by the functionality or the hardware you are going to use it for than there are a couple of extra criteria to consider:
- Is it well supported in your environment
- Is it cost effective
- Does it perform well
If none of these matter, than go with whatever you fancy.
Windows/Linux/Solaris/BSD/AIX/VMS/etc everybody has their pet OS and the best OS for you is the OS you think is the best OS for you. Of course I have my preferences (and that is usually anything but Windows) but I am realistic enough to see that there are enough criteria where I would chose windows above anything else.
Answer: This discussion will be closed by an admin shortly.
Jihadi concerns aside, the only answer is to use what is best for your business. Be pragmatic, use the best solution to solve a problem. You never know, it may not include using Windows or Linux.
Personally I try to avoid windows, but if it was the best fit, I would use it.
Answer: My production servers are all on Linux. All needed services can be set up on it and I don't really see any other reason to use Windows Server then Support. But with Linux you have a community of people that help each other and lots of HOWTOs on the web.
Maybe the compatibility is an advantage in the beginning. The set up of Windows Server should be faster then the Linux one, but on a long run I wouldn't trust trust Windows about safety and reliability.
Answer: I would use windows server only if explicitly required by the customer, or if I think that I as a vendor will have less support hassle since customer staff knows only windows.
Answer: It all depends on what your server is going to be servering your users. In general I would say you get what you pay for, what you don't pay for you will have to work for instead.
You have to be more precise on what your criterias are or this will turn on a religious war sooner than you think.
Answer: I think there are three main reasons to use Windows in preference to Linux

If you have Windows specific software then Windows is the best platform to run it.  Most vendors of server-side Windows software will probably not support it on Wine, although they would tend to support it on a VM.
If your network staff are familiar with Windows you will save on retraining costs if you stick with Windows.
Quite often a Windows based solution will be the best tool for the job.  Where you have the option of running equivalent software on Linux or Windws the Windows based solution may simply be the best for your requirements.  In this case it makes sense to use it unless you are in the position of having Unix skills available but no equivalent Skill base in Windows.


How to add an application specific service contextual menu for an automator created service

Question: I have just created a service for my text editor.
I would like to be able to add a services item in the text editor contextual menu when right clicking.
Can this be done?
Answer: Depending on your service restrict it to your text editor while creating the service in Automator and save it to ~/Library/Services/.
Example:

After selecting some text, the context menu offers the service "fiona-babbles":


NN Architecture for the detection of "sparse" Objects

Question: I have a document digitalization task where I want to detect technical drawings from images. These Images mostly consist of objects made up of combination of shapes like lines, circles and rectangles. See this example: .
What I want as the result is a detection of all "objects" in this image like e.g. switches, wirings and devices that are present.
I already tried multiple network architectures like:

YOLO
DeepLab
UNet (for Pixel based classification)

Generally I observe that all these approaches work well for small objects but have big problems with "bigger" objects due to their "sparsity". I guess thats not surprising if you consider the nature of CNNs.
One one hand my task seems simple due to things like

high contrast
limited set of shapes (or "poses") for the different objects

But I think CNNs all have problems with the "sparseness" of the objects as its only the boundary that is detectable and the inner is often empty.
Has anyone here an Idea which architectures to try or links to papers to read for these kinds of problems?
Ideally I would like to get the list of objects as output but I am unsure how to encode this in the NN as e.g. YOLO does this by an approach that would not work in my scenario, I think (merging all "inner" boxes that show the same object).
Thanks already!
Answer: Have you looked at Deformable DETR? These Transformer models are extremely good at detecting big objects because of the Global Attention mechanism.
Comment: Thanks, I will have a look later to see if this could improve my results


What is the probability that at least 3 people have the same birthday in the same year

Question: Consider a group of size 40. What is the probability that at least three
members of the group were born in the same month and in the same day (same birthday)?
Ignoring leap years.
Comment: http://math.stackexchange.com/questions/25876/probability-of-3-people-in-a-room-of-30-having-the-same-birthday
Answer: Calculate the number of possibilities for everything that doesn't make the cut.
Here's what doesn't make the cut:

All birthdays different
Exactly $1$ pair the same; all others different
Exactly $2$ distinct pairs the same; all others different
...
Exactly $19$ distinct pairs the same; all others different
Exactly $20$ distinct pairs the same

Line the $40$ people in a row.
If all birthdays are different, there are $365$ possibilities for the first, $364$ for the second, all the way to $326$ for the fortieth.
In other words,
$$P(0) = \prod_{n=0}^{39} (365-n),$$
where $P(0)$ is the number of distinct pairs that are the same.
Now, let's look at $P(5)$.  Let's choose the five birthdays $_{365}C_5$ and arrange them chronologically.  Pick a pair from the lineup $_{40}C_2$ for the first birthday, another for the second $_{38}C_2$, all the way down to the fifth $_{32}C_2$.  Then, for the people that are left, there are $360$ possibilities for the first, $359$ for the second, all the way down to $331$ for the thirtieth.
In other words,
$$P(5) = {365 \choose 5}\left[\prod_{n=0}^4 {40-2n \choose 2}\right] \left[ \prod_{n=0}^{29} (360-n) \right].$$
By extension,
$$P(n) = {365 \choose n}\left[\prod_{m=0}^{n-1} {40-2m \choose 2}\right] \left[ \prod_{m=0}^{40 - 2n - 1} (365-n-m) \right].$$
Then, the probability you want is
$$P = 1 - \frac{\sum_{n=0}^{20} P(n)}{365^{40}}.$$


Why didn't Germans simply set Fury on fire?

Question: While watching Fury the other night, aside from stunning visuals and great acting I've noticed something rather peculiar. Considering Fury depicts the end of war by which time Germans should've seen enough and developed tons of fighting experience, why didn't they simply set the tank on fire? This would seem like the easiest and most intuitive solution to me.
Comment: @Dannie use a Molotov Cocktail, the Finnish used them to do that against Russian Tanks invading Finland. Other nations also used similar weapons against tanks. The Sherman burnt so well it was known as the 'Ronson' a popular brand of lighter or a 'Tommy Cooker' by the Germans.
Comment: How do you set a tank on fire?
Comment: You can either kill the people/crew inside the tank with a grenade. But as the movie went through, the crew did lock them self inside the tank
Answer: Because it is an unrealistic movie scene.
Yes, the Germans were extremely good in taking out tanks with improvised means. And a lone tank needs movement to be effective against infantry, else it is dogmeat. There was one incredible situation where Audie Murphy (read the Wikipedia entry) did such a stunt by standing in a burning tank destroyer and using a 0.5 gun to mow down everything the Germans sent against him, but he was really in completely different weight class as soldier.
Otherwise, the Germans would simply encircle the tank and destroy it with

Molotov cocktails. They work best if they burn on the top and they will suffocate/smoke out the engine/crew. This is the reason tanks need movement and/or protection from other tanks to make a small target and if hit, present the least vulnerable sides.
Throw a handgrenade into the cannon pipe.
Use a flamethrower against the openings.
Bind several handgrenades together to form a bundled charge and place it under the tank bottom to use it as improvised tank mine.

The movie is simply said highly unrealistic.
Comment: I'd like to add that in my opinion THAT scene is highly unrealistic. From what you stated in real life the crew would know all this and never even consider staying in the tank as they would die for nothing, plus the Germans acted completely idiotic simply throwing themselves at the front of the tank. Even with the surprise they would be clever enough to retreat, take ground and just circle it, at the very least to hit it from behind. Apart from all that the rest of the movie is quite realistic, I think. I saw a YouTube video of a real tank operator confirming other scenes were exactly right.
Answer: I am not completely sure, but I think that a reaction to the success of Molotov cocktails in the Finnish-Sovjet war was to change the design of air intake and exhaust to point downwards, so that burning petrol would not run into the engine. So in 1944 it was more difficult to set a tank on fire then in 1940.
However, once you get really close to a tank with broken tracks, you will find a way to destroy it. The British home guard was trained in doing so, the Germans in Fury probably only learned that to destroy a tank you shoot it with a panzerfaust. In the film we see that the troop is low on anti-tank grenades, and when they use it, they miss. So it is reasonable to assume that the Germans are highly motivated but poorly trained Volkssturm, who try to solve a problem by beating there head against a wall.
Comment: It was confirmed by Brad Pitt's character that the Germans were an SS platoon.
Answer: if you set a tank on fire from the outside, it wont burn. the only real way to set a tank on fire is to puncture its fuel tank and light it(this usually happens when a cannon round or an anti tank rocket round strikes the rear any where the fuel tanks are. a grenade with enough force can achieve this (german bk 2h))


Correct magnitude spectra of a cosine DFT?

Question: I've just started my course on DSP and haven't laid my hands on MATLAB yet. I was wondering if the plot of the magnitude spectra was correct for the below shown $x(n)$:
Answer: HINT:
As mentioned in the comments you're missing one component. See it this way,
Using Euler's formula you have:
$$\cos\left(\frac{2\pi k_0 n}{N}\right) = \frac{\exp\left(j\frac{2\pi k_0 n}{N}\right) + \exp\left(-j\frac{2\pi k_0 n}{N}\right)}{2}\tag{1}$$
And using the DFT definition, you have:
$$
X[k] = \sum_{n=0}^{N-1}x[n]\exp\left(-j\frac{2\pi k n}{N}\right)\tag{2}
$$
Plugging equation $(1)$ in $(2)$ you get:
$$
X[k] = \underbrace{\frac 12\sum_{n=0}^{N-1} \exp\left(-j\frac{2\pi (k - k_0) n}{N}\right)}_{\rm yours} + \frac 12\sum_{n=0}^{N-1} \exp\left(-j\frac{2\pi (k + k_0) n}{N}\right)\tag{3}
$$
Your plot got only the one with the under-brace.
EDIT:
Using geometric series, equation $(3)$ can be written in the form:
\begin{align}
X[k]=\frac 12\sum_{n=0}^{N-1}a^n + \frac 12\sum_{n=0}^{N-1}b^n
\end{align}
Where
$$\text{with}\quad a = \exp\left(j\frac{2\pi (k_0 - k)}{N}\right)\quad\text{and}\quad b = \exp\left(j2\pi\frac{-(k_0 + k)}{N}\right)$$
In the first summation you get $0$ everywhere except for $k = k_0 + pN \ \forall \ p\in \mathbb Z$ where you get $N$ (summation of $1$s). In the same manner in the second summation you get $0$ everywhere except for $k = pN - k_0\ \forall \ p\in \mathbb Z$.
Comment: Yes agreed . I'd like an explanation without the math.Here is how I see it : In the dft definition the summation yields a non zero value only for k=ko (the basis function e^(-j2 πkn/N) will have frequency equal to that of function being analysed for k=ko) . I don't understand how the summation will yield non zero value at k=N-ko
Comment: @asr please see my edit.
Answer: The broader principle is that the DFT of any real signal is conjugate symmetric between the bottom half and the top half.  This can be understood in more of a conceptual manner by observing that a DFT bin value is the calculation of a weighted set of N Roots of Unity, where the signal value is the weighting factor and the bin index is the skip size traversing the roots.  The signal is wrapped around the circle $k$ number of times for the $kth$ bin.  Skipping ahead $N-k$ roots is the same as skipping backward by $k$ roots, which is then simply a wrapping in the opposite direction.  Therefore, the center of mass will also be in the opposite direction which happens to be the complex conjugate.
This means for every real valued signal, the bin value at index $k$ is the complex conjugate of the bin value at $N-k$.  This is how robert bristow-johnson could tell you that you were missing a value without doing any math.
I have written a blog article "DFT Graphical Interpretation: Centroids of Weighted Roots of Unity" to explain what I mean by the "wrapping" above.  I don't think you will find it anywhere else.  The reason the magnitude value is 1/2 can be clearly seen in Figures 2 through 6.
I hope this helps.
Ced
Answer: you're missing the frequency component at $k=N-k_0$.
Comment: Could you explain how you arrived at that without the mathematics
Comment: A cosine always has symmetric spectrum.
Comment: Hopefully someone will correct if I'm wrong but to explain why they are two components, here's my understanding.  (I'm new at this also ). When you use 0 to N-1 in a DFT, you are impliciitly making the frequency spacing from 0 to $2 \pi$. So the   $k = k_{0}$ component represents one frequency  and the other represents the same  frequency but at $2\pi - k_{0}$. So, they are really the same frequency which is why the magnitude of each  is $\frac{1}{2}$. If N instead went from -N./2+1 to N/2, a similar thing happens but, in that case you'd be going from $-\pi $ to $\pi$.


Can't figure out how to set up java debug adapter Neovim

Question: I've been getting into Neovim more and I quite like it so far. I need to use java for university in a couple months so I've been setting that up. I've gotten java to run pretty good, but I'm running into issues setting up the debugger.
My config is based off kickstart.nvim, I cloned it a couple weeks ago and decided to go off on my own from there.
I tried to follow a guide to setup the java debugger  after a bit of trouble shooting I managed to download java-debug and vscode-java-test using mason (which was 10x easier than the way they did it, I had a lot of issues). Afterwards the guide said to put the following code in a file, which to my knowledge attaches jdtls to the buffer.
...

local HOME = os.getenv "HOME"

-- Debugger installation location
local DEBUGGER_LOCATION = HOME .. "/.local/share/nvim"

-- Debugging
local bundles = {
  vim.fn.glob(
    DEBUGGER_LOCATION .. "/java-debug/com.microsoft.java.debug.plugin/target/com.microsoft.java.debug.plugin-*.jar"
  ),
}
vim.list_extend(bundles, vim.split(vim.fn.glob(DEBUGGER_LOCATION .. "/vscode-java-test/server/*.jar"), "\n"))

local config = {
  ...

  on_attach = require("config.lsp").on_attach,

  -- If you don't plan on using the debugger or other eclipse.jdt.ls plugins you can remove this
  init_options = {
    bundles = bundles,
  },
}
...

I tried to change that code and put it in my own config, with a notable change being that I changed the path vim.fn.glob() gets because it didn't line up with the files I had, the result of that is the following (from line 500 in init.lua in my config if anyone wants to see that)
local HOME = os.getenv "HOME"

local DEBUGGER_LOCATION = HOME .. "/.local/share/nvim/mason/packages"

local jdtlsBundles = {
  vim.fn.glob(
    DEBUGGER_LOCATION .. "/java-debug-adapter/extension/server/com.microsoft.java.debug.plugin-*.jar"
  ),
}
vim.list_extend(jdtlsBundles, vim.split(vim.fn.glob(DEBUGGER_LOCATION .. "/java-test/extension/server/*.jar"), "\n"))

local serverSettings = {
  -- clangd = {},
  -- gopls = {},
  pyright = {},
  -- rust_analyzer = {},
  -- tsserver = {},
  jdtls = {
    init_options = {
      bundles = jdtlsBundles
    }
  },

  lua_ls = {
    Lua = {
      workspace = { checkThirdParty = false },
      telemetry = { enable = false },
    },
  },
}
-- Setup neovim lua configuration
require('neodev').setup()

-- nvim-cmp supports additional completion capabilities, so broadcast that to servers
local capabilities = vim.lsp.protocol.make_client_capabilities()
capabilities = require('cmp_nvim_lsp').default_capabilities(capabilities)

-- Ensure the servers above are installed
local mason_lspconfig = require 'mason-lspconfig'

mason_lspconfig.setup {
  ensure_installed = vim.tbl_keys(serverSettings),
}

mason_lspconfig.setup_handlers {
  function(server_name)
    require('lspconfig')[server_name].setup {
      capabilities = capabilities,
      on_attach = on_attach,
      settings = serverSettings[server_name],
    }
  end,
}

Then finally the guide says to copy the following code in a file /lsp/init.lua so I assume that's to setup the lsp.
function M.on_attach(client, bufnr)
  ...

  -- Configure for jdtls
  if client.name == "jdt.ls" then
    require("jdtls").setup_dap { hotcodereplace = "auto" }
    require("jdtls.dap").setup_dap_main_class_configs()
    vim.lsp.codelens.refresh()
  end
end

From my understanding the last function in the previous code block does that, so in the on_attach function that it calls I copied this code directly. (line 480 in init.lua in my config).
Kickstart.nvim itself already has some setup done for nvim-dap, copying it all here seems overboard but this seems like the relevant part:
        require('mason-nvim-dap').setup {
            automatic_setup = true,

            handlers = {},

            ensure_installed = {
                'delve',
                'java-debug',
                'vscode-java-test',
            },
        }

as far as I remember I never changed this, but 'java-debug' and 'vs-code-java-test' aren't in base kickstart.nvim so I may have added those and forgotten.
From this point, the guide suggests things should be working, which they half are. When I'm in a java project, pressing F7 does give me a few windows that seems to be debug related (albeit that they're empty) however if I try to continue/run the debugger I get the error no configuration found for `java`. You need to  add configs to `dap.configurations.java` (see `:h dap-configuration`) The guide suggests to run the command :JdtRefreshDebugConfigs, but that command doesn't exist for me.
And there I'm stuck right now, I've looked around a little for ways to solve my problem, but frankly I don't even know where to look, so I just decided to make a post here (this is  a cross-post from a post on Neovim discourse https://neovim.discourse.group/t/cant-seem-to-figure-out-how-to-set-up-the-java-debug-adapter/4216). If anyone knows how to point me into the right direction, or knows what I'm doing wrong, any help is much appreciated! (please keep in mind that I'm pretty close to a complete beginner, so this could be a simple mistake I made)
Answer: you should change the client name to 'jdtls',
 -- Configure for jdtls
  if client.name == "jdtls" then

Comment: Welcome to [vi.se]! This answer would be better if you [edit]ed to include details (teach 'em to fish), such as how someone could figure this out for themselves next time they have an issue with the `client.name` property


Problem with appending model after previous linking

Question: Just starting to add external models to my scenes. I first tried linking a model but found that it wasn't really suitable for what I wanted since I couldn't apply changes or edit the model. I deleted the object from my scene and appended instead but still couldn't apply or edit. I tried with an older version of my scene by appending and I am able to apply and edit with no issue so it seems that somehow linking first has left something lying around that is causing me problems. I tried making everything local and that didn't help. Is there any way to see or "cleanup" these items that might be causing me trouble? (Or is it perhaps something else?)
Answer: Well, putting it into words helped me look for the answer. In the outliner, there's a drop down which lists orphaned data. I cleaned that out and then I was good to go. There's also a clean up->purge option in the file menu but I never got to try that.


Using a JWT for more than authentication

Question: Should JWTs be used for more than just authenticating a user? I read that it's okay to store non sensitive stuff like a user ID in it. Would it be okay to store stuff like permission levels in the token? This way I get to avoid doing a database call.
Comment: JWT tokens can be used for authentication purposes, but nothing stops you from storing user roles or a scope with the access level of the token.
Comment: upvote because this is the answer I wanted to hear
Comment: Depends on the specific type of JWT. If you use HMAC, then any verifier of the token can also forge other tokens and get more access rights. Perhaps you should use RSA and make sure that only a single entity has the private key.
Answer: JWT tokens can be used for authentication purposes, but nothing stops you from creating your own claims to store additional data, such as the user roles or a scope of access.
Some authentication providers add a scope of access to their tokens. Have a look at this answer.
Comment: Is that answer talking about refreshing tokens?


Sum of All Real Numbers on $[0,1]$?

Question: So I'm pretty confident that the answer is infinity, because the sum of all real numbers on $[0, 1]$ is greater than the harmonic series. However, I don't understand why the following integral can't be used to solve this problem: $$\int^1_0x\,dx$$ Wouldn't this integral add up infinitely small $x$ values to get the correct answer? But the answer I get when I integrate is $0.5$ I'm still pretty new to integration, so I apologize if it's something extremely simple.
Comment: It does not add up all the real values $x$ in $[0,1]$, instead it adds up all the real values times a very very small number d$x$ (of course this is not a rigorous statement).
Comment: @Levent Ohhhh that makes so much more sense. Thank you!
Comment: By the way if you try to add an uncountable number of positive numbers you will get $\infty$. Hence we don't define an uncountable sum.
Answer: Adding all real numbers in any interval is not quite the same as integrating $xdx$ on that interval. You can think of integration as finding the area under the curve (here the curve $y=x$) between the limits 0 and 1.
I am not quite sure how one would formulate the problem of adding all real numbers in any interval as an integration problem. The area you are looking for is that of an infinite number of rectangles with very small widths but unit height. Hope this gives you some insights on how to think about integration.
Comment: Thank you for the explanation! I figured that integration was just finding the area under some graph, but I never really understood how to apply it. I'm mostly interested in using integration to calculate infinite sums, but as you can see, I need some practice with that haha.
Comment: Integrating with respect to the counting measure on the reals is basically just summing them, FWIW.
Answer: No uncountable sum of positive terms can be convergent in the usual sense. To see this, partition the positive reals as $$[1,\infty), [\frac 12,1), [\frac 13, \frac 12),\cdots$$
As there are only countably many slots, one of them must contain infinitely many of your summands and the sum of those alone will diverge.
Answer: By doing an integration you are summing up the values of the function (here $x$) times some width ($dx$). Basically this yields the area under the curve.
Comment: Yeah that's what threw me off. I was assuming that $dx=1$ which isn't the case here. Thank you for the quick answer!

Sum of All Real Numbers on $[0,1]$?


ESP32: How to run two independent PID controllers, one per core?

Question: I want to control 2 independent processes with 2 PID controllers. Is it possible to run each controller on a separate core? I'm using this PID library. According to its documentation, the PID::Compute() function should be called once every loop(). How can this be achieved when using RTOS tasks (for multi core execution)?
Comment: why not put both  PID::Compute()  and  PID2::Compute() in loop()? it still will be called once per instance
Comment: No that would work but the PID computation algorithm will only run on a single core and that's not what I want to achieve.
Comment: still one core runs WiFi
Answer: esp32_technical_reference_manual_en.pdf
Page 620
As mentioned before, only an elevated process with PID of 0/1 can initiate a process switch. The new process
may have any PID from 0 ~ 7 after the process switch. The key for successful proactive process switching is that
Espressif Systems 620
Submit Documentation Feedback
ESP32 Technical Reference Manual V4.3
29. PID Controller
when the last command of the current process switches to the first command of the new process, PID should
switch from 0/1 to that of the new process.
The software procedure for proactive process switching is as follows:

Mask all the interrupts except NMI by using software.
Set register PIDCTRL_NMI_MASK_ENABLE_REG to 1 to generate a CPU NMI Interrupt Mask signal.
Configure registers PIDCTRL_PID_DELAY_REG and PIDCTRL_NMI_DELAY_REG.
Configure register PIDCTRL_PID_NEW_REG.
Configure register PIDCTRL_LEVEL_REG and PIDCTRL_FROM_n_REG.
Set register PIDCTRL_PID_CONFIRM_REG and register PIDCTRL_NMI_MASK_DISABLE_REG to 1.
Revoke the masking of all interrupts but NMI.
Switch to the new process and fetch instruction.
Though we can deal with interrupt nesting, an elevated process should not be interrupted during the process
switching, and therefore the interrupts have been masked in step 1 and step 2.
In step 3, the configured values of registers PIDCTRL_PID_DELAY_REG and PIDCTRL_NMI_DELAY_REG will
affect step 6.
In step 4, the configured value of register PIDCTRL_PID_NEW_REG will be the new PID after step 6.
If the system is currently in a nested interrupt and needs to revert to the previous interrupt, register
PIDCTRL_LEVEL_REG must be restored based on the information recorded in register PIDCTRL_FROM_n_REG
in step 5.
In step 6, after the values of register PIDCTRL_PID_CONFIRM_REG and register
PIDCTRL_NMI_MASK_DISABLE_REG are set to 1, PID Controller will not immediately switch PID to the value of
register PIDCTRL_PID_NEW_REG, nor disable CPU NMI Interrupt Mask signal at once. Instead, PID Controller
performs each task after a different number of clock cycles. The numbers of clock cycles are the values specified
in register PIDCTRL_PID_DELAY_REG and PIDCTRL_NMI_DELAY_REG respectively.
In step 7, other tasks can be implemented as well. To do this, the cost of those tasks should be included when
configuring registers PIDCTRL_PID_DELAY_REG and PIDCTRL_NMI_DELAY_REG in step 3.
Espressif Systems 621
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Answer: Sure. The existing Arduino setup and loop are just executed in their own task:
void loopTask(void *pvParameters)
{
    setup();
    for(;;) {
        if(loopTaskWDTEnabled){
            esp_task_wdt_reset();
        }
        loop();
    }
}

extern "C" void app_main()
{
    loopTaskWDTEnabled = false;
    initArduino();
    xTaskCreateUniversal(loopTask, "loopTask", 8192, NULL, 1, &loopTaskHandle, CONFIG_ARDUINO_RUNNING_CORE);
}

So there's no reason not to replicate that to give yourself an entire new setup and loop, or just a single function that does it all if you prefer.
TaskHandle_t secondPidTaskHandle;

void secondPidLoop() {
    // setup code here
    for (;;) {
        // PID loop code here
    }
}

void setup() {
    xTaskCreateUniversal(secondPidLoop, "secondPidLoop", 8192, NULL, 1, &secondPidTaskHandle, 0);
}

void loop() {
    // First PID code
}

The last parameter to xTaskCreateUniversal() is the core to execute on. The default setup/loop runs on core 1:
#define CONFIG_ARDUINO_RUNNING_CORE 1

So just use 0 and it'll run it on core 0.


Low Air Pressure

Question: Can we create low air pressure artificially in a system to make the wind blow towards the system from the higher normal air pressure in vicinity ?
Answer: Of course we can.
One example would be in ventilation systems that utilize fans and blowers.  Supply ductwork for example would have blowers putting air into the ducts at higher pressure than atmosphere.  This high pressure "pushes" the air through the ducts towards the lower pressure surrounding air.
Something like exhaust ductwork does it in reverse.  The fan sucks air out of the ductwork, causing a low pressure which gets "pushed" by the higher pressure air of the surroundings through the ducts and out of the building.
So basically, yes, and this is is a crucial part of examining airflow, especially in closed buildings or large weather systems.
Comment: can we do this by making air warm in a system ? making the air warm in a system will make the air rise and will cause low air pressure in the system and then wind can flow from the higher air pressure around it towards the low air pressure in the system. can we make such a system or is there any example of that ?
Comment: @Alex Heating it up in a closed space should cause the pressure to increase (ideal gas law).  If you heated it up, with an opening for it to expand into, it will push itself into that space and maintain the same pressure.  You would need to heat it up with an opening so that it maintains pressure, then cool it down with the opening closed if you wanted it to get below atmospheric pressure.

Low Air Pressure


Can we use "now" with simple past tense as in "I saw it now"?

Question: Can we use "now" with simple past tense? For example, Let's say someone is trying to show me something, but I can't see it. Right after seeing it, can I say, "Ok. I saw it now"?
Answer: You could but it's not very formal. You might hear this in informal/regional usage or you could use it to establish a character's dialect, but it's not "good English".
If you have just seen it but you are no longer looking at it it would be better expressed as...

I saw it just now
I just saw it
I've just seen it
Now I've seen it

If something has just come in to view and you're still looking at it

I see it now
Now I see it
I now see it (very formal)

But (and this is a stretch) if

you were a time traveler trying to remember when you first saw something and you went back in time to the first time you saw the thing
you were watching yourself on a CCTV recording of you seeing a thing

I guess you might say Ok, I saw it now.
Comment: Even in the case EllieK describes I would say `OK, I see it now` or just `Ok, I saw it`. I think this use of `see` drifts in to a slightly different meaning of `to see` something, closer to saying `I understand now` or `i get it now`. `I watched the film once and I didn't see the foreshadowing, but I watched it again yesterday and I SEE IT NOW.`
Comment: Good answer you may want to incorporate some of Foogod's observation in the comments that explain *OK, I saw it now,* could be used when you have re-watched something several times in an attempt to see something you previously missed and you finally do see it -- a variation of, *I saw it this time.*
Answer:
Right after seeing it, can I say, "Ok. I saw it now"?

Yes, but keep in mind it would be a shortcut for saying "Ok. If someone were to ask you if I have seen it, you can now say yes".
If you are supposed to keep looking at this thing with the person showing it to you, rather than simply complete the task of seeing it, you should say "Ok. I see it now."
Comment: I actually don't entirely agree with this.  If what you mean to say is "if someone were to ask you if I have seen it, you can now say yes", I think that would normally be expressed as "I *have seen* it now", not "I saw it now".  If what you mean is "I saw it, and the time I saw it was just a moment ago", then you could say "I saw it *just now*" (which is very standard, I think, not just a South African thing).
Comment: To me, "I saw it now" actually means "I saw it *this time*", that is, it would be used if there is something which has occurred several times, and you did not see when it happened previously, but you did see it on the most recent occurrence (which just happened).
Comment: Lots of people would say: **I saw it just now**, meaning a few moments ago - although this may be part of my South African upbringing.
Comment: @LawrenceC Thank you. So you think it is okay if we use "now"with simple past tense, right?


Issue in viewing double values

Question: I am having an issue with viewing double data in matlab console. Actually, I am importing a matrix from my data file. The value of a particular row and column was 1.543 but in the console when I use disp(x) where x is the matrix imported, it is showing as 1.0e+03 * 0.0002. However, when I try to access that particular element in the matrix using disp(x(25,25)) where 25 and 25 are the row and column numbers it is showing to be 1.543. So I am confused. Any clarifications. It is just that when I print the whole matrix it is showing as  1.0e+03 * 0.0002.
Answer: That happens due to high dynamic range of your data.
Try for example :
 x = [10^-10 10^10];
 disp(x);

The result is:

1.0e+010 *
     0.0000    1.0000

It looks like the first value is zero, but it isn't. It is almost zero compared to the second one. That is not surprising. Try to add to the big value the small one, and subtract, and you get zero. That is due to floating point arithmetic.The following expression is true
 isequal( (x(1)+x(2)) - x(2) , 0)

What can be done?
1) A really high dynamic range can cause troubles in any kind of computations. Try to understand where it came from, and solve the problem in a broader context.
2). You can try to set
 format long

It can improve the situation visually for some of the cases.
Answer: The following command should fix it. It is only a display issue, the precision of the actual values in the matrix are not affected:
format shortG

Issue in viewing double values


Changing instruments in midi encoding?

Question: I'm trying to write a function to dynamically create midi files on Android. Since there is no javax.sound.midi library I'm just writing the bytes out to file myself. I've found some great guides (see below) so I've been able to create multiple track midis. However I haven't been able to figure out how to switch instruments for any of the tracks so everythign is just using the default instrument.
I think from the documents I read the code I need is to "program change" followed by the program number.
What I've tried so far is writing the following out to a byteoutputstream array:
<code>track.write((byte) 192); // 128 + 64
track.write((byte) x); // x is the instrument number between 1-128.
</code>
I've put this before the start of the note on/ note off track information, but it doesn't seem to do anything except make the midi take a long time to start. Am I on the right track here, or am I missing something? Any help is appreciated.
http://faydoc.tripod.com/formats/mid.htm
https://ccrma.stanford.edu/~craig/articles/linuxmidi/misc/essenmidi.html
Answer: Finally figured it out. It was a just a simple thing, but I forgot to include track time before the program change. Once I added the 0 byte it worked.

Changing instruments in midi encoding?


How can I help my betta who is laying at the bottom of his tank?

Question: My kids saw the "My Fun Fish Tank" on TV.

(Not mine, but an example of what the tank looks like)
I got it for them and after I put it together I went to the pet store and got a male betta. I change the water every 2 days with distilled water, and we feed him like the instructions that came with the tank told us to, but I'm worried that the fish doesn't have enough oxygen because he doesn't move very much, he stays at the bottom like he's gotten stuck under the rocks.
Why is my betta acting like this, and what can I do to make him better?
Comment: @jaci If it were oxygen he'd probably be gulping at the surface. Bettas are unusual fish in that they have what's called a "labyrinth" organ, which allows them to breathe air somewhat.
Comment: Distilled water might well have less oxygen in because of the distilling process - that's why I asked where you got it from. And fish slow down if they are too cold as well. Siamese fighting fish are a tropical fish - you may need a heater, depending on how warm your room is. You definitely need a thermometer to measure the tank temperature if you don't have one.
Comment: What is the temperature of the tank?
Answer: A couple of things to look at are tank size, temperature, and location.
If that's actually the size of tank, its too small.  While they do 'rest' a lot, bettas are actually fairly active fish.  Watch them sometime in a big planted tank.  They are very curious creatures, and like to explore and peck around for something to eat and/or chase.  In a small tank like that movement is restricted - especially laterally.  There's just no place for him to go.
Also, a cold betta is less active.  If the temperature of the water is below 76-78-ish, bettas will slow down and become less active.  So you may need a heater.  But, that bowl may be too small for even the smallest paddle heater.  Pet shops sell small thermometers that can attach to the side of the bowl to help you monitor that.
The other thing to consider is boredom.  Bettas are, by fish standards, pretty intelligent.  If the betta is stuck over in a corner or in another room away from the action... he's going to get bored.  They like stimulus.  Move them someplace where's there's some activity.  This way there's some big splotches of colors moving around them to stir them up occasionally.
Also, last issue - do not use distilled water.  That is very different from the water they are used to.  You might use bottled spring water (not purified water).  But I've seen little difference in how bettas react to spring water and plain (dechlorinated) tap water.  But, every area is different so it really depends on what your local water is like.
My personal recommendation for a happy betta... I would not keep a Betta in anything less than 1 full gallon.  Generally the bigger the better, but I have had some that had trouble adapting to bigger tanks after living in a cup for their entire life.  I keep mine in 5 gal tanks with small in-tank filters & heaters, plants, and in the center of the house so that there's always a lot of movement for them to watch.  Partial water change every week (I just scoop some water out and replace it).  They are very active fish...  sometimes a bit too active (mine will sometimes jump at me as I walk by, so I never fill the water to the top.  Many a betta has found their end by jumping out of their own bowl).
Comment: This is a good answer but could be improved with reference(s) for the distilled vs spring water points.
Comment: Related [Is distilled or spring water better for fish tanks?](http://pets.stackexchange.com/questions/6564)
Answer: Unless you are remineralising your distilled water, you will have a very unstable pH, which may well be the cause of the problems you are seeing. Distilled water does not have the minerals necessary to buffer pH.
How much water are you changing? You should do regular partial water changes, complete water changes can be stressful for fish. Because of the tank size, I would recommend doing regular and large water changes (but not full), perhaps 50% daily.
The tank is too small, a betta should really be in a 20L or bigger tank.
You may want to test your water parameters, test kits can be picked up from most pet stores.
Answer: When you say, you clean the water every two days, do you mean you pour the water in so that the dirty water goes into the cup? Or are you changing the fishes tank, giving new water?
I actually think you might be changing his water too often. Plus you're using distilled water. Remember, fish come from dirty water usually. You of course want it clean, but by using distilled water you're going above and beyond what's right for him, unintentionally making him sick.
When you bought him did you give him time to adapt to the water? Was the tank and accessories cleaned with warm water, no soap, before dropping in the tank?
I really don't care for the fish tank because he has no oxygen, except for when you pour the water in. They have great little starter fish tanks there small and perfect for bettas, I would invest in one of those. They come with a filter and a plastic ornate tree too.
We had two bettas for over two years never sick, they moved from California to Kansas with us. Bettas are tough.
One thing they did like us to have, was a mirror by their tank, or another betta to look at. They flare up looking at each other or into a mirror. It gives them something they enjoy. So yours could be depressed also.
Comment: Just a note on the mirror. Mirrors are good as long as you take them away after an hour or so. The flaring up is a sign of aggression, it's them trying to scare the other betta out of it's territory. So when that betta disappears, it can be a confidence booster, but if it never disappears, then you might see your betta start to become submissive since it's unable to defend its territory.
Comment: There's no mention of decorations, so if there aren't any, I agree that it could very well be stressed at having an empty tank. And a mirror might be a good way to keep him from boredom - as long as it's not with him constantly.
Answer: If your betta is lying at the bottom of the tank, are his fins clamped? This indicates some illness.
The tank is way too small. Keeping any fish in a cramped space is not proper. A small tank has less buffer for water parameter changes.
Bettas are tropical, so a tropical range of temperatures is required.
Also, remember that in an understocked tank, water changes should not be this frequent.  Fishes like the betta, which generally thrive in paddy and rice fields, are used to water with a higher general hardness a.k.a gH. You can achieve this by not using distilled water, or by dissolving just a single rice grain sized rock salt crystal, in a glass of de-chlorinated water, and then adding it to the tank water.
Use some substrate, like some small pebbles or some rocks to give a chance for the beneficial bacteria to colonize your tank.
Also remember to never change the water completely. Always perform a PWC, or a partial water change, of up to 20% only.
Answer: He could have bladder swim disease. He may have a bloated stomach if you look close. It common if you purchased out of pet store. The cups they come in are not heated and they do not have space to exercise. If they are too cold and do not have space to move they stay at rest. This causes them to eat more then they burn off. You can try not feeding him for three days and then feeding a quarter of a boiled frozen pea. Also, you can buy a seven dollar water heater. If he is warm he is more likely to move around.
Comment: Welcome to Pets SE. :) Where did you hear about feeding frozen peas to fish? I thought you could only feed the flake stuff from the store.  (not that i'm a fish aficionado)
Answer: He could just want to lie down. The do like to rest. Get him a betta bed. Mine love them. You put it near the surface of the water so they can lie down just under the water. I have a leaf one.
Answer: Use spring water it's what betta live in in their natural habitat if you use another  kind of water your fish could die. if you do you can use the conditioner to treat it
Comment: please update your answer and tell more about water quality and the needs of bettas.
Comment: _'If you use another kind of water your fish could die'_ - This isn't true. Can you update your answer to explain what you mean?


Do all transactions show in metamask wallet?

Question: Bare with me I'm new here :) I've been selling art on Rarible but I can't tell if the Eth is going into my account. Because I'm minting nft's I can't keep track of my Eth total. My wallet activity doesn't say received when I sell something so that's where I'm getting confused. My Metamask extension always has errors on the manage extensions page and if I hover the cursor over the eth total on my wallet it always says "Balance may be outdated". Should incoming and outgoing activity show up on my wallet? Is Etherscan the log for Metamask or can a transaction show successful on Etherscan and get blocked because of a Metamask error?
Answer: Unfortunately internal transactions are not displayed by Metamask. See this report https://github.com/MetaMask/metamask-extension/issues/565.
Due to the decentralized nature of blockchain you should check multiple sources to be sure the balance is correct. Most of the time they will match and be correct but there is no guarantee.
Etherscan is a separate project from Metamask it shows more detailed information like blocks, transactions, accounts, etc. It is usually very used in the community.


Effective ways to discipline my 5 year old

Question: My five year old can be challenging at times. She just started kindergarten this year and has improved with her behavior some, but still makes bad decisions that she knows better than to make. She can be disrespectful to adults at her school and think nothing of it. I don't understand! She is very strong willed and confident and maybe a little too confident at times! Any suggestions?
Comment: Hi Leslie, and welcome to the site. Have you searched "discipline"? There is a lot of information available, and reading some of the questions/answers might not only give you some answers, but might also help you narrow down your question to help with your particular situation (e.g. what you've tried that others have suggested, and what hasn't worked, etc.)
Comment: This is incredibly broad - could you give us more information to work with, please?
Answer: In general, kids are often looking to test boundaries of grab attention.
So two basic principles are 1) to establish transparently clear  boundaries, as in listing a very short, limited set of words that are not acceptable at home; and 2) to keep emotions and attention to the minimum in response to behavior you want to limit and instead reward good behavior.
You can also let her be in charge of herself and ask her to find herself, be proud of herself, be better than before, the best she can. This type of 'ownership' of her own behavior might put it in a different perspective.
Otherwise, there's a 'character development' set of tools that can be useful:
 there's books, cards, etc. with short stories about honor, respect, patience, perseverance, teamwork, etc and how they are valuable.


private interfaces or abstract classes: what are my choices

Question: So here is my problem:
I have used a number of interfaces in my project to help maintain good coding style, however, the design of my software suggests I may be able to export this as a library that I and others can use.
The problem is that of accessibility.  In some of my interfaces I do not want others to have access to the methods, but Java enforces them to be public. This is OK in my own projects but I don't want others to be able to access these methods.
For example, I have one interface called Sprite with some of the methods below
Sprite:
void update(Room room);
void draw(Room world, Canvas c);
void updateHealth();
void updateLocation(Room room);
int getLayer();
void shoot();
void setDirection(Direction direction);
...

This is good because all Sprites need these methods but some of them such as draw() I only want my Game Engine to use.
What are my options?
Comment: A private interface makes no sense, interfaces are used to communicate an API. Therefore the compiler rejects it.
Answer: I would say, narrow the interface of Spirte and move the methods you want to be private to AbstractSprite subclass. This is the easiest way.
Answer: Abstract classes should be fine if:

you can have some common implementation (even if it's a very simple one like a couple of properties)
you have to define those protected methods
and your THINGS are the same kind of objects (is-a relationship). You are saying "all my sprites" so you are saying: "all are sprites of some sub-type".

So... in your case, it seems that an abstract class would fit well.
Don't be afraid. If you need interfaces you can define them later, too (even abstract class implementing an interface with a subset of methods).
Or if you need a change, you can refactor.
Answer: What about creating a (or multiple) Facade?
If you have a larger set of classes/interfaces playing together in your library, then a Facade provides a controlled 'interface' to the outside world. More concretely, for your Sprite you can divide your interface into two interfaces: one which is available to the outside world through your Facade, but doesn't include things like draw(). And something like a DrawableSprite for your internal usage. Your internal objects would of course implement both of these interfaces then.
Answer: Java allows 4 levels of access private, protected, public and default. (default is with no keyword) Java in a Nutshell calls it default Sun java tutorial also says package-private
default allows access to from classes in the same package.
So in this case make interfaces that only you should access be default so cannot be seen from outside your package.
For Sprite you need to split into 2 interfaces
public Sprite containing the ones that external code can use.
default for only the Game Engine
The object you make for use by Game Engine can extend both interfaces,


Can we have electric current in vacuum?

Question: Suppose we a have an anode and cathode and between them there is vacuum. If we apply a sufficiently high voltage between them, can we have a small electric current?
Answer: Yes, if you apply a high enough voltage, electrons will be able to leave the cathode (the potential energy from applied voltage need to be above the workfunction of the cathode material). Essentially you then create an electron beam. This is the basic principle of a vacuum tube, a cathode ray tube (tv tube) and an electron microscope.
It is even possible to create an arc in "vacuum". This happens when the cathode or anode material evaporates (every material, including metals, has a non-zero vapor pressure) and the gas (evaporated metal) then becomes ionized and becomes conductibe. Then of course we do not have a true vacuum anymore. The message is that as long as we have electrodes in a fixed compartment we cannot have ideal vaccuum. This in turn then can even lead to arcing. This for instance happens in vaccuum power switches.
Answer: Electric current is just the flow of electric charge due to the movement of charge carriers from one place to another. You don't even need a cathode/anode or any source of p.d to constitute a current. If you set an electron, proton or any other charged particle in motion in an isolated vacuum, it will continue moving with a uniform velocity ( Newton's first law) and thereby constitute a current.

Can we have electric current in vacuum?


How do you transfer weight paint in blender 2.8

Question: How do you transfer weight paint in blender 2.8? I want to transfer the weight paint of my character to my clothes?
Answer: As of the stable release of 2.80, Transfer Weight option is consolidated into Transfer Mesh Data, and now located under Object > Relations > Transfer Mesh Data. This option is already available in Object Mode, no need to enter Weight Mode and accidentally paint a weight data in the process.
However, the selection order for the Transfer Weight is somehow reversed. So, instead of transferring weight from the first selection to second selection, it's actually vice versa in 2.80 - the tool transfers weight from the second selection to the first selection.
Answer:
I know this is late but it still might be helpful to others :-)
Answer: You can use Data Transfer Modifier on your clothes mesh and select Vertex Data, Projected Face Interpolated (experiment here), Vertex Groups, All Layers > By Name.
Comment: Data Transfer Modifier does not work fine in 2.8. Only old metod in 2.79 works correct


Induced Electric Field Cause

Question: Why does a changing magnetic flux induce an electric field? When a coil moves through a magnetic field, the induced emf is due to the Lorentz force. But why does a changing magnetic flux produce an induced electric field and emf even though the coil is stationary or there is no coil?
Answer: It is an experimental fact, As already discussed in scientific community, It is very difficult to Answer a "why" question, because answers to these "why" questions are always given so that the understanding shifts from one frame to another, that is you understand other facts with help of accepted and satisfactory basic fact/axiom/theory, In this case, for learning it first time, just accept That Electric field Is produced whenever Magnetic flux is changed, and then Understand Other things in Electrodynamics using these
Answer: It is mostly about moving charges, i.e. electrons. These have their own electric field as well as a magnetic field and interact with external electric respectively magnetic fields.
An external magnetic field causes an alignment of the dipole direction of the magnetic field of the electron. If the external magnetic field varies, photons are emitted from the electron and the electron is deflected. At the same time, the magnetic alignment is disturbed. By changing the external magnetic field, this process is repeated.
To prove this phenomenon, it is sufficient to observe whether the power loss for changing the magnetic field increases when electrons are in this field and whether EM radiation is produced by the electrons in the process.

Induced Electric Field Cause