Why are divergence and curl related to dot and cross product?

Question: I've been reading Griffith's intro to electrodynamics and I've been a bit confused about his explanation of divergence and curl. I don't understand how divergence is the dot product of a gradient acting on a vector function and curl is the cross product of gradient acting on a vector function. Does it relate to the fact that one uses sine while the other uses cosine? Just to clarify, I understand the concept of divergence and curl from a purely conceptual standpoint, it's just this mathematical definition that I can't wrap my head around.
Answer: First of all let's define dot product and cross product between two 3-vectors $$\mathbf{a} = \begin{pmatrix} a_1 \\ a_2 \\ a_3 \end{pmatrix} \qquad \text{and}  \qquad \mathbf{b} = \begin{pmatrix} b_1 \\ b_2 \\ b_3 \end{pmatrix}  $$
dot product:
$$ \mathbf{a}\cdot\mathbf{b} = \sum_i a_i b_i = a_1 b_1 + a_2 b_2+ a_3b_3 $$
cross product: $$ \mathbf{a}\times\mathbf{b} = \begin{pmatrix} a_2 b_3 - a_3 b_2 \\a_3 b_1 - a_1 b_3 \\a_1 b_2 - a_2 b_1  \end{pmatrix} $$
Note that these definitions do not involve geometric quantities like the angle between the two vectors; indeed, it is the angle that is defined in terms of the dot product (for the records, $\cos \theta := \mathbf{a\cdot b}/ \sqrt{\mathbf{(a\cdot a)(b\cdot b)}}$).
Then you have the definition of divergence and curl acting on a function $\mathbf{f}(\mathbf{x}) \equiv \begin{pmatrix}f_1(\mathbf{x}), f_2(\mathbf{x}), f_3(\mathbf{x})\end{pmatrix}$ ($\mathbf{x} = (x_1,x_2,x_3)$; you can call $x_1=x$, $x_2=y$ and $x_3=z$ but my choice allow a compact notation):
divergence:
$$
\mathrm{div}\, \mathbf{f} :=   \frac{\partial }{\partial x_1} f_1+\frac{\partial }{\partial x_2} f_2+\frac{\partial }{\partial x_3} f_3 = \sum_i \frac{\partial }{\partial x_i}f_i \equiv \sum_i {\partial_i}f_i
$$
where $\partial_i \equiv \partial / \partial x_i$.
curl:
$$
\mathrm{curl} \,\mathbf{f} := \begin{pmatrix}
\partial_2 f_3 - {\partial_3 f_2} \\
  \partial_3 f_1 - \partial_1 f_3 \\
\partial_1 f_2 - \partial_2 F_1\end{pmatrix}
$$
Now you can see that if you introduce the quantity $$ \nabla = \begin{pmatrix} \partial_1 \\ \partial_2 \\ \partial_3 \end{pmatrix} $$
you can write the operations of divergence and curl as if $\nabla$ was a vector! Indeed if you apply the definition of dot and cross product you can easily find out that
$$
\nabla \cdot \mathbf{f} = \mathrm{div}\,  \mathbf{f} \qquad \text{and} \qquad
\nabla \times \mathbf{f} = \mathrm{curl}\,  \mathbf{f}
$$
You can find out that many identities holding for 3-vectors still hold id one of them is $\nabla$.
But note that this "trick" of thinking to $\nabla$ as a 3-vector is formal and not all identities holding for usual 3-vectors keep working.
Comment: So are you saying that, in hindsight, one can make the connection that since finding divergence requires taking the partial derivative of each component of a vector, it is basically the same as taking the dot product between each component of that vector?
Comment: What I am saying is that if you forget that $\nabla$ is a differential operator and you just think to it as a vector, you get the correct expression for divergence and curl, as I showed in the answer. I would not consider it more than a formal correspondence that is *sometimes* useful to remember some identities during calculations. For instance, it is true that $\mathrm{div} \, \mathrm{curl}\, \mathbf{f} = 0$; if you write in terms of $\nabla$ you get $\nabla \cdot \nabla \times \mathbf{f}$, it looks like the usual identity  $\mathbf{a}\cdot \mathbf{a}\times\mathbf{b}=0$ valid for vectors.
Comment: So from a conceptual standpoint, the divergence must be a dot product because we're trying to find the capacity of each point of a vector function being a "sink" or "faucet" (since dot product requires multiplying each component by the magnitude of the same component of the other vector)? Also, the reason I'm still confused about curl is because I don't get why the cross product is necessary. How would one realize that finding the amount a vector curls around a point requires subtracting each multiplied component with itself? I guess I'm having trouble connecting the visuals with the math
Comment: Take for instance the divergence $\mathrm{div}\,\mathbf{f}:=\sum_i\partial_if_i$; this is the *definition* of div. Now, *without having any relation with this*, you have the dot product between two vectors $\mathbf{a}\cdot\mathbf{b}=\sum_ia_ib_i $. Look at the RHS of these two equations: you have the sum over terms formed by couples of objects: $f_i \leftrightarrow b_i$ and $\partial_i\leftrightarrow a_i$. Now you see that if you introduce "the vector of partial derivatives", that is $\nabla=(\partial_1,\partial_2,\partial_3)$, you can (formally) identify div with $\nabla \cdot \mathbf{f}$ .
Comment: An analogous argument holds for curl, but the expression (written in my answer) are not suitable for a comment.
Comment: I stress that this correspondence between curl and div with cross and dot product is **formal**. Indeed the differential operators satisfy identities that *look like* vector identities if written in terms of $\nabla$. It is **not** the fact that $\nabla$ looks like a vector that makes those identities true.
Answer: The somewhat cavalier way that operators are used and notated in physics (especially once you reach QM) has always bothered me a bit, so I can definitely relate. First, let's define some terms.
We define the gradient operator $\vec{\nabla}$ as a vector of partial derivatives along each coordinate. Here, we'll assume Cartesian as it's easiest to work with (Griffiths provides the forms for cylindrical and spherical coordinates in the front cover):
$$\vec{\nabla}=\hat{x}\frac{\partial}{\partial x}+\hat{y}\frac{\partial}{\partial y}+\hat{z}\frac{\partial}{\partial z}$$
This can be applied to a scalar function $f$ to obtain $\vec{\nabla}f=\frac{\partial f}{\partial x}\hat{x}+\frac{\partial f}{\partial y}\hat{y}+\frac{\partial f}{\partial z}\hat{z}$.
The divergence of a vector function $\vec{v}=v_x\hat{x}+v_y\hat{y}+v_z\hat{z}$ can be given by div $\vec{v} = \frac{\partial v_x}{\partial x}+\frac{\partial v_y}{\partial y}+\frac{\partial v_z}{\partial z}$. If we try to form the "dot product" of $\vec{\nabla}$ and $\vec{v}$, we multiply the magnitude of each component with the magnitude of the same component of the other vector, and then add. In doing this, we apply the derivative operators that are the components of $\vec{\nabla}$, so we get something that's identical to div $\vec{v}$. For this reason, even though the reasoning is still a bit fast and loose from a mathematician's point of view, we can reasonably write:
div $\vec{v}=\vec{\nabla}\cdot \vec{v}$.
A similar argument to the above yields:
curl $\vec{v}=\vec{\nabla}\times\vec{v}$.
Answer: The mechanism of the divergence as a dot product has been explained well by other answers. I will introduce some quite informal but intuitive observations that can convince you as to why the curl is a cross product.

The right hand rule for cross products follows naturally into the curl. Recall that the right hand rule tells you what direction the vector generated by a cross product will point in. This is necessary because the cross product gives us a vector orthogonal to both of the original vectors, but there is an ambiguity as there is more than one vector that satisfies orthogonality. Now consider the following vector field:

Curl the fingers in your right hand and you will notice that your thumb points in the direction that all the vectors in the plot of the aforenoted field's curl does:

You've just taken the cross product of the del operator with the vector field, and the resulting plot of the curl is consistent with the right hand rule.

The torque exerted on a tiny stick pinned down at its center in a vector field (picture winds, or moving water) is proportional to the curl of the vector field at that point. This makes since both from intuition and from the fact that torque is defined as the force crossed with the distance from the pivot that the force was applied to.
Answer: I love this question and was very curious about it, so I built on a 3blue1brown video to answer it with the video below. I'd argue one doesn't fully understand/appreciate divergence, curl or Maxwell's equations unless they get this. Here's the nutshell version:
This connection is difficult to conceptualize because the del operator, $\nabla ,$ is not a typical vector. Like a parasite or virus, it is meaningless alone, and needs a 'host' to 'operate' on.  While you can't think of it as a real vector, you can treat it like one and use the standard processes for dot and cross products. This yields the equations for the divergence and curl as shown below, which simply boil down to finding 4 components: $\frac{\partial P}{\partial x}, \frac{\partial Q}{\partial y}, \frac{\partial Q}{\partial x}, $ and $\frac{\partial P}{\partial y} $.
If your $\frac{\partial P}{\partial x} $and $\frac{\partial Q}{\partial y} $ are positive, this means the $x$ and $y$ components of your vectors are getting larger when you move in the $x$ and $y$ direction, respectively, which corresponds to positive divergence.
If your $\frac{\partial Q}{\partial x} $and $\frac{\partial P}{\partial y} $ are positive and negative, respectively, this means the $y$ and $-x$ components of your vectors are getting larger when you move in the $x$ and $y$ direction, respectively, which corresponds to counterclockwise rotation, or positive curl.
The vector field illustrated below has a larger positive $\frac{\Delta P}{\Delta x}$ value than it's negative $\frac{\Delta Q}{\Delta y}$value, corresponding to a slightly positive divergence. It also has a positive $\frac{\Delta Q}{\Delta x}, $and negative $\frac{\Delta P}{\Delta y}$, corresponding to a positive (counterclockwise) curl.

I attempt to explain this more clearly in the video if you'd like to check it out, and let me know if you'd like to discuss further!
https://youtu.be/k7WyPNWerN0


Completely disable module

Question: I know you can disable Magento2 module output in the admin interface, but I'd like to remove some modules (eg. wishlist, RSS, newsletter) completely. We don't need them and I'd expect Magento to be a little faster if less code has to be loaded.
So I disabled the modules using bin/magento module:disable --force, but that broke some frontend pages like the customer dashboard.
How can I prevent the theme from trying to load a disabled module? I don't understand why Magento is so modular if disabling a module can break the site...
Answer:
Delete folder app/code/YourVendor/YourModule
Run the command:
php bin/magento setup:upgrade

If you are in developer mode that is it. If you are in production then run:
php bin/magento deploy:mode:set production

Now you are all set.
Answer: You can also do that in the admin panel in configuration , advanced, advance , find your module and disable it in the drop down menu and save.
Comment: It would be really nice if you could actually read the question before you take the time to answer

Completely disable module


Is it alright to have a leather jacket and still consider myself a Buddhist?

Question: Ok well I got the leather jacket years before I started to follow Buddhism. Would it be alright to still have the coat, or do I have to give it to a friend, or someone else?
Comment: Related but not exactly the same question: https://buddhism.stackexchange.com/questions/36636/what-do-buddhists-think-of-leather and Dhamma Dhatu's answer includes a scriptural reference.
Additionally I would add that from a purely ethical and ecological standpoint, continuing to use your old leather jacket rather than buying an imitation leather one (or any other new one) prevents fast-fashion waste, especially since a good leather jacket can last for decades.
Answer: In MN 55, the Buddha did not prohibit the eating of meat. This scripture concludes a monk cannot accept an offering of meat for food if it is known or suspected an animal was specifically killed for the explicit purpose of feeding a monk or monks.
Browsing the internet, my impression is leather is basically a by-product of the cattle & other animal meat & dairy industries. While animal rights organizations discuss the differences between leather as a 'by-product' vs a 'co-product', my impression is, in most cases, animals are not killed primarily for their skins. This situation appears similar to the principle the Buddha established in MN 55, where meat is not forbidden for monks when an animal is not killed specifically for monks.
In summary, while the Buddha exhorted laypeople to follow the Five Precepts, the 1st of which is undertaking the training to refrain from killing living beings; and while the scriptures also say carrying on a business of animals for slaughter is wrong livelihood for the business owner; the Buddha was silent about the finer details of how ordinary people should acquire food.
While I do not explicitly support the slaughter of animals, the problem with the arguments of animals rights activists is if there was no meat industry, the vast majority of cattle & similar animals would not even exist. The meat industry is a secular matter and not anything related to Buddhism.
In conclusion, it appears having a leather jacket would not be against Buddhist principles.


Does "He takes away" (John 15:2) allude a christian with no fruit will lose their salvation?

Question:
"I am the true vine and my Father is the gardener. He takes away every branch that does not bear fruit in me. He prunes every branch that bears fruit so that it will bear more fruit." (John 15:1-2 NET)
Comment: Please see the Tour and Help, below. The answer you have supplied (which you supplied at the same time as you asked the question) is not an hermeneutic answer, but merely quotes commentaries. I think you have misunderstood the purpose of Biblical Hermeneutics and misunderstood the question/answer form operated by Stack Exchange.
Comment: The main question should be : what does 'fruit' mean in practical terms ? What does 'fruit' look like ? How do I know if I am 'fruitful' or not ?
Comment: The parable speaks more on the "bearing fruit & not bearing fruit" and the consequences thereof, so should we not?  I can see your suggestions though have valid points in them, but not relevant to the question.
Comment: Define "christian" in your question.
Comment: In the text,  Christian is a "branch in Me (Jesus)" and Father (God) expects fruits.
Answer: John 15:2 - Will a Christian with no fruit lose their salvation?

"I am the true vine and my Father is the gardener. He takes away every
  branch that does not bear fruit in me. He prunes every branch that
  bears fruit so that it will bear more fruit." (John 15:1-2 NET)

Jesus Is the Vine—Followers Are Branches—The Father is the Vinedresser.
Jesus is "the true vine, and his Father, the vinedresser. After likening his disciples to "branches" of the vine, he urged them to remain in union with him. Just as branches of a literal vine must remain attached to the trunk in order to remain alive and fruitful, the disciples need to remain in union with Jesus to be spiritually alive and be productive.
Cultivating the fruit of the spirit contributes to your happiness now, and to your future salvation.  (Matthew 5:3)
Galatians 5:22-23  (KJV)

22 But the fruit of the Spirit is love, joy, peace, longsuffering,
  gentleness, goodness, faith, 23 Meekness, temperance: against such
  there is no law.

Love moves others to love you in return.
Joy gives you the strength to cope with challenges.
Peace helps you to keep your relationships free of strife.
Long-suffering enables you to stay happy even when you are under trial.
Gentleness draws others to you.
Goodness on your part makes others respond when you need help.
Faith will assure you of God's loving direction.
Meekness  will bring you calmness of heart, mind, and body.
Temperance or  Self-control means that your mistakes will be fewer.
Comment: Mt. 5:3 seems not relevant to the discussion.
Comment: You have not commented on what is the significance of the "Father will cut off the branch not bearing fruit"  in relation to one's salvation?
Comment: Sam King : ( Mt 5:3)For a  literal vine to be productive it requires to be taken care of , it requires watering, fertilizer, pruning e.t.c. Likewise, a person must satisfy his spiritual needs to stay in union with Christ, and to be spiritually alive and productive. To manifest the qualities of "the fruitage of the spirit" (Gal 5:22-23) you need to have  a regular and quality reading of the scriptures, This is why I quoted Mt 5:3
Comment: Jesus describes this severe pruning: "If anyone does not remain in union with me, he is cast out as a branch and is dried up; and men gather those branches up and pitch them into the fire and they are burned." (John 15:6) No Salvation. Mt 3:10, Heb. 6:4-8
Comment: The words in Mt. 3:10 & Heb 6:4-8,  are speaking &  pointing to what will be their final fate (people described in the verses) than temporary rebuke  or passing "through the fire."
Comment: Sam Kim their fate is everlasting death, with no hope of resurrection which is the second death. The Lake of fire is symbolic of everlasting destruction Rev. 20:14 This evidenced by the fact that death and hades are hurled into it, both are intangible things that cannot be literaly burned by fire.
Answer: First, let us establish what "fruit" is.  The Greek word is καρπός (karpos) which is used of literal fruit quite rarely (eg, Matt 7:17, James 5:7, 18, etc).  It is mostly used metaphorically.  Let me quote W E Vine (Expository Dictionary of NT Words):

works or deeds, fruit being the visible expression of power working
  inwardly and invisibly, the character of fruit being evidence of the
  character of the power producing it, Matt 7:16.  As the visible
  expressions of hidden lusts are the works of the flesh, so the
  invisible power of the Holy Spirit in those who are brought into
  living union with Christ (John 15:2-8, 16) produces "the fruit of the
  Spirit", Gal 5:22, the singular form suggesting the unity of the
  character of the Lord as reproduced in them, namely "love, joy, peace,
  longsuffering, kindness, goodness, faithfulness, meekness,
  temperance", all in contrast with the confused and often mutually
  antagonistic "works of the flesh".

However, there are more metaphorical uses of "fruit" than just fruit of the Spirit.  Here are some more:

Converts as a result of outreach ministry, John 4:36, Rom 1:13, Phil 1:22
Spiritual growth through deliverance from a life of sin, Rom 6:22
The reward for being a servant of God, Phil 4:17
The effect of making confession of faith by the sacrifice of praise, Heb 13:15

Which is intended in Jesus' parable of the vine?  Probably all of the above.  With this understanding, the parable of Jesus about the vine (John 15:1-8) is simple to understand.

Christ is the vine and we are the branches (V5)
Those branches ("Christians") who do not bear "fruit" are pruned out and cut off from Christ (V2)
Such pruned branches are thrown into the fire and destroyed (V6)

The idea that some unfruitful Christians will be removed or shut out from Christ is often expressed in the Bible.  In this parable Jesus tells us to "remain in me" (V7).  Let me list other places where people can be lost at some point following their initial commitment to Christ:

The "wilderness generation" of Israelites that God called out of Egypt perished in the desert because, despite being called, turned their backs on God and refused to trust in God by believing the majority spy report.
At the end of the wilderness wandering, Joshua begged the people to choose to serve God, Josh 24:15, 22.  See also Deut 30:19, Judg 5:8, Job 34:4, 33, 21, Ps 119:173, Prov 1:29, 3:31, Isa 7:15, 16, 56:4, 65:12, 66:3, Jer 8:3.
King Saul who was a statesman and prophet called by God (1 Sam 10:11, 12, 19:24), yet was ultimately lost when he consulted demons for advice and then committed suicide.
Ps 69:28 contains a plea for David's enemies to be blotted out of the book of life!
Eze 18:21-28 also teaches that the wicked can reform and be saved, and the righteous can apostatise and be lost.
Rom 11:17-21 discusses the warning that people who had been grafted into the "olive tree" of the Christian community could be broken off if they were unfaithful.
1 Cor 9:27 Paul says he disciplines his body to keep it under control so that after preaching to others he does not become a castaway/disqualified.  That is, Paul believed that it was possible that he could lose his way and become lost.
1 Tim 6:10, For the love of money is the root of all kinds of evils.  It is through this craving that some have wandered away from the faith and pierced themselves with many pangs.
Similarly, Heb 6:4-6 also teaches that some "who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit…" can fall away.
Heb 10:26, If we(!) deliberately keep on sinning after receiving the knowledge of the truth, no sacrifice for sins is left
Heb 10:29, How much more severely do you think someone deserves to be punished who has trampled the Son of God underfoot, who has treated as an unholy thing the blood of the covenant that sanctified them and who has insulted the Spirit of grace.  This verse clearly shows that it is possible to be sanctified and subsequently lost.
Heb 10:35, Therefore, do not throw away your confidence which has a great reward.
Heb 10:36, You need to persevere so that when you have done the will of God you will receive what he has promised.
Heb 13:9, "Do not be led away by diverse and strange teachings, for it is good for the heart to be strengthened by grace …"
2 Peter 1:10, "make your calling and election sure".  This clearly allows for the possibility of losing one's election.
2 Peter 2:21, "It would have been better for them not to have known the way of righteousness, than to have known it and then to turn their backs on the sacred command that was passed on to them."
2 Peter 3:17 contains a very stern and sobering warning to be on guard that we do not fall from our secure position.  Verse 14 contains a similar warning.
1 Cor 10:12 also contains a stern warning from Paul, "If you think you are standing firm, be careful that you don't fall."
Gal 6:9 says, "Let us not become weary in doing good, for at the proper time we will reap a harvest if we do not give up."
Jesus' parable of the 10 virgins contains two classes of people called "wise" and "foolish".  All were invited to the wedding; All were virgins symbolising purity, see Rev 14:5; All had lamps, ie, lights symbolising Christ as the light of the world, John 1:4, 9, 8:12, 9:5, Matt 5:14-16; All, at least initially had oil - but this is the crux of the parable - five virgins had enough oil and five did not have enough because they complained that their lamps were going out.  In the NT oil represents the gift of the Holy Spirit (Luke 4:18, Acts 10:38, 2 Cor 1:21, 22, 1 John 2:20).  Thus, Jesus teaches that some who are called and have been given the Holy Spirit (see also Heb 6:4-6) can still be excluded from the Kingdom of God.
Jesus' parable of the vine (John 15:1-8) says two interesting things: (a) that branches (connected to the vine of Jesus) that do not bear fruit are cut off (v2); and (b) the bearing of fruit is to prove that we are Jesus' disciples.
Jesus' parable of the sower, or perhaps the parable of the soils (Matt 13:1-23, Mark 4:1-20, Luke 8:4-15) contains several classes of people (soils) who start out well in the Christian life but lose their way.  The conclusion is also significant: "by their constancy bear fruit". (Luke 8:15)
Jesus' parable of the banquet (Luke 14:16-24) contains a very good example of people rejecting the call (or "election") of God as well as God having to ask some people more than once and begging them to the wedding banquet.  Jesus' conclusion is, again, significant, "not one of those men who have been invited shall taste of my banquet."

Bearing fruit is not something that can be done the Christian's effort - it is a miraculous work of the Holy Spirit within us.  See Eph 2:8-10.  A very similar question is asked here >> Is eternal life only for overcomers?
Comment: Does not Christian's have to yield to the leading of the Spirit to bear fruits?
Comment: "Bearing fruit...  is a miraculous work of the Holy Spirit within us."  Amen to that.
Comment: Very much appreciated. +1.
Comment: Quite right - completely agree @SamKim
Answer: I just want to focus in this comment on the correlation of the "fruit-bearing" and "salvation", which I believe is the important point Jesus wants to teach.
And I am citing two theologians who see the correlation yet from different perspectives.
Calvin says in his commentary:
"Can anyone who is engrafted into Christ be without fruit? I answer, many are supposed to be in the vine, according to the opinion of men, who actually have no root in the vine. Thus, in the writings of the prophets, the Lord calls the people of Israel his vine, because, by outward profession, they had the name of The Church."
Armenian view: (I do not have the direct comment of Arminius)
"The doctrine of apostasy, in Arminian theology, primarily concerns an attempt at being faithful to God's word. We refuse to deny what is rendered evident in the Hebrew and Christian scriptures, warning believers about falling away (John 15:1, 2, 3, 4, 5; Heb. 2:1, 2, 3; 3:12, 14; 4:1) -from "Jacob Arminius Refutes William Perkins on Perseverance" Sept. 3, 2015 (Society of Evangelica Arminians)
Summary:
Calvinism:  If one bears no fruit, never was saved.
Armenians:  If one bears no fruit, will lose salvation.
Both view the "fruit-bearing" has a crucial "bearing" on one's salvation yet reach entirely opposing conclusions.
My personal view is: proper exegesis will show in the parable that,
Jesus giving an exhortation to His disciples, branches that Father did the grafting, (to us as well) to remain in Him, the True Vine, (as stated in v 4,5,6,7,& 10)- that they may bear fruits that Father will not cut them off.
Comment: Those commentaries quoted , I believe are of hermeneutic answeres of the two theologians, though different in conclusions. It should be oblivious  only one of the two is right.
Comment: This is not an hermeneutic answer to the question.
Answer: In your question you  assume that salvation is something that one possesses and not a future event.
John 15:2 is a good example of one who is really "in" Christ who does not remain in him and so is cut off the vine and destroyed.
I make those points here.
Answer: This question sounds like "Can only those who are not bald participate in the haircut tournament?" and such a question is analytically self evident, for haircut tournament means that the bald cannot participate there in principle.
Similarly, "no fruit" means that a person is deprived of fruits of the Holy Spirit (Galatians 5:22-23) and in virtue of this depravation is unhappy and miserable, while Kingdom of Heaven is not for the unhappy and miserable, but of those who are happy through bearing those Divine Joy-Providing, i.e. Heavenly Kingdom-Providing fruits, for Heavenly Kingdom=Heavenly Joy and Peace in Holy Spirit (Romans 14:17). To make it even clearer: the Heavenly Kingdom is not something adventitious that is vouchsafed to someone who bears fruits, but the very bearing of fruits of the Holy Spirit is the reality of the Heavenly Kingdom.
On the contrary, "every tree not bearing fruit will be cut and cast to fire" (Matthew 7:19), which means that such a "tree" cannot be a part of the "garden" in the Kingdom of Heaven.
Comment: "Fruit  (καρπὸν)" in the parable that the Farmer expects in Gr. is "singular" and it refers, first and foremost, the fundamental change of quality (character):  from a wild grape to "the heavenly grape of True Vine" -Christ likeness; old-self crucified, now "Christ lives in me." As this change  progresses and more yielding in obedience to the Word and to the Spirit, more of the "fruit of the Spirit "-singular, yet has multi facet,  i.e. love, joy, peace,etc (Gal 5:22-23)  the branch will bear.  Gr. "μὴ" (not) in the "not bearing fruit" signifies  the subjective decision of the branch.
Comment: The only difference you put here is that I say "fruits" and you say "facets" of one fruit. I have no objection, since all those are divine energies that are different but come from the same Source. It is a linguistic difference of expressing one and the same reality.
Comment: Gal 5:22- "fruit -καρπὸς is in "singular", meaning  the works of Holy Spirit manifests in  9 different virtues yet related all to one Spirit.
Comment: Yes, sure, no objection to that: one can say both: 1) Champion-making work of Mohammad Ali is brilliant movement, great jab, superb uppercut, clever manoeuvring, and 2) Champion-making works of Mohammad Ali are brilliant movement, etc. since all relate to one person, they either one says "works" or "work" the same obtains, for nowhere in my answer lurked any glimpse of an absurdity that I assumed several Holy Spirits with a proper workings to each of them.
Answer: The fruit in John 15 are converts. I chose you, and I set you that you should go forth and bear fruit and that your fruit should remain, that whatever you ask the Father in My name, He may give you. 15:16. Often I purposed to come to you (yet was hindered until the present), that I might have some fruit among you also, even as among the rest of the Gentiles. Rm 1:13.
"Save" and "salvation" are not directly subjects (or words) in Jn 15. They're arrived at by the warning in 15:2, 6, especially by the words "fire" and "burned." But "fire" and "burned" here refer to discipline, not to eternal destiny. This is because the branches are "in Me." 15:2. To be "pruned" is a dealing by the Lord. A more severe one, in the nature of true loss, is to be "taken away." Neither equals eternal condemnation. If anyone's work is consumed, he will suffer loss, but he himself will be saved, yet so as through fire. Do you not know that you are the temple of God, and that the Spirit of God dwells in you? If anyone destroys the temple of God, God will destroy him; for the temple of God is holy, and such are you. 1 Cor 3:15-17. (Cf Rv 2:11.)
Thus both Arminianism and Calvinism, from your Answer, are mistaken in this regard. They both miss the truth--they both miss the One they purport to talk about. You're correct that gospel fruit-bearing is important. It's the charge at the end of all four Gospels, and one of the things John is engaged in in writing this very book: Jn 20:23, 29, 31; 1:12; Lk 24:47; Mk 16:15-16; Mt 28:19-20. 28:19-20 and Jn 21:15-17 also touch on the subject of "remaining fruit." He said to Him, Yes, Lord, You know that I love You. He said to him, Feed My lambs. He said to him again a second time, Simon, son of John, do you love Me? He said to Him, Yes, Lord, You know that I love You. He said to him, Shepherd My sheep. He said to him the third time, Simon, son of John, do you love Me? Peter was grieved that He said to him the third time, Do you love Me? And he said to Him, Lord, You know all things; You know that I love You. Jesus said to him, Feed My sheep.
Comment: V2,  "he takes away (αἴρει - v-P.I.A.)) -αἴρω" (to raise, to take up, lift) in "indicative, active" -used to means "pulls away, tears away, taken away (i.e. Mt 9:16 -the patch pulls away from the garment; Mt 13:12; 21:43; Mk 4:15...), and together with  in v6, "thrown out (ἐβλήθη ἔξω)  "dried up", "they gather them and cast into fire and it is burned"   refers more to the final fate than  "just suffer the lose."
Comment: Why does it "refer more" so (to you)?
Comment: Those specific words in v6, "thrown out (ἐβλήθη ἔξω)"   "dried up", "they gather them and cast into fire and it is burned"  are specific terms that refer to " final  fate", the finality, not "suffer loss" in 1Cor 3:15.
Comment: There's finality of permanence in believing into Christ, Rm 10; so that although we need to finish the race, there's no possibility, and thus never a need, of having to start it all over, Heb 6. The specific words "branches in Me" in Jn 15, match "believers," "farm," "temple," and "builders upon the foundation" in 1 Cor 3 by Paul. Unless you want to imagine a difference? Our God is a **consuming** fire, Heb 12:29; Malachi 3:2; 1 Cor 3:13, 15. Whereas the lake of fire's work has no end, Rv 20:10; Isa 66:24. You and others here appear to make the second birth of John 3 Pelagianistic in some way.
Comment: God did not change His mind and make Adam/Eve to eat the "fruit."  But they made that ill-fated decision, it was an emotional decision, and caused own "fall,"  and Holy, Sovereign God's law of justice carried out. Likewise, yes, the "grafting" was permanent, yet as Gr. Gr. "μὴ" (not) in the "not bearing fruit" signifies, it was the subjective decision of the branch, against the will of the farmer, God. All prescriptive words of God in the Bible carry consequences!. Lets remember, God is Sovereign, He does according to His will, not to what we assume He will do or should do! He is God, not we!
Comment: Walter, the words of God is above theologies, theologians, and particular doctrinal positions. Let the Scripture speak!  God's  word saves, nothing  else.
Comment: I believe we're supposed to have discussions elsewhere. So my last word (here) can be that I don't see the relevance of Adam and Eve. They were not regenerated, but were created, Gen 3:24; then fallen then justified, 3:20-21. Justification and regeneration aren't merely subjective choices by grace in faith, they're once-for-all legal then organic (ontological) changes. They're irrevocable gifts, Jn 3:16; Eph 2:8. God's sovereign will chose and predestinated believers before the foundation of the world, to sonship. He's not an "Indian giver," to borrow a phrase, and no insult to Indians. Thanks
Comment: You seemed to view the state of being  "created in the image and likeness of God"  is lower than the being "regenerate.
Comment: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/107563/discussion-between-walter-smetana-and-sam).
Comment: The Scripture is the ultimate source for "true" answere, and let us seek with open mind with prayers.
Answer: The vine was always Israel, do a word search for VINE . The vine was uprooted  from Egypt to the land of Israel. When Israel is referred to as the vine it is never good.
Jesus says that he is the true vine,  he is the Israel of God who will obey God the Father perfectly, the branches are Israel.  There is no mention of the branches being grafted into the vine, so these branches grew with the vine. This passage of scripture is about Jesus and Israel not gentiles because gentiles are the body of christ and grafted into the olive tree. This passage is about Jewish disciples who stopped believing or stopped walking with him, Notice this passage is about the little flock Jesus is discoursing with his 11, he hasn't died yet and the holy spirit has not been given, gentiles are not granted repentance till Acts 10 and 11. This is not about gentile believers losing salvation at all. Its about unbelieving Israel's being cut off Romans 11:24
Read Ezekiel 15.
There is so much in this passage to exegesis, Jesus tells them that they are clean through the word that I have spoken to you, Jesus in John 6 Jesus tells the 12 will you also leave Peter says you have the words of eternal life , John 8  he says my words do not abide in you.
1 Peter 2:3, Ephesians 5:26. Pray this helps God bless your studies
Comment: I think you need to provide some evidence for these assertions
Comment: In the text John 15:2, it says,  "I am the true vine" and that answers! Also, remember, here, "I am" is one of the seven "I am" statement Jesus refers to Himself.
Comment: Ezekiel 15

 2  Son of man, What is the vine tree more than any tree, or than a branch which is among the trees of the forest?

 3  Shall wood be taken thereof to do any work? or will men take a pin of it to hang any vessel thereon?

 4  Behold, it is cast into the fire for fuel; the fire devoureth both the ends of it, and the midst of it is burned. Is it meet for any work? note

 5  Behold, when it was whole, it was meet for no work: how much less shall it be meet yet for any work, when the fire hath devoured it, and it
Comment: Read Ezekiel 15 the entire chapter
Comment: The fruit is to make desciples
Answer: Context and more verses are needed. The branch that does not bear fruit "is thrown away and dries up; and they gather them, and cast them into the fire and they are burned."
Is the branch that does not Bear Fruit a true Christian by definition? Someone who has been Filled with The Holy Spirit. Not at all.
The Branch that does not Bear Fruit is a Wolf in Sheep's clothing, the ones who stand before Christ and say "Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness"
It's important to note that these people are not pretending to cast out Demons and Prophesy in Jesus's name, they really are doing it. These are people who have The Holy Spirit and were given authority by God to cast out Demons, Prophesy and do many mighty works, But they were not Filled with The Holy Spirit. Like those in The Old Testament, the Holy Spirit will come and go, but it is not Living in them.
Our Prime example is Judas who in Matthew 10:1-4 was given authority by Christ over unclean spirits, to cast them out, and to heal every disease and every affliction. But Yet in John 6:70 Judas is called a Devil by Jesus Himself.
So Christ gave a Devil The Authority to cast out a Demon, that is the definition of a Divided Kingdom that Will not stand. "And if Satan has risen up against himself and is divided, he cannot stand, but is coming to an end."
But once Satan's kingdom is fallen there will be no more use for those Devils, so they'll be thrown into the fire and Destroyed.
Comment: Does not the words, a wild  branch (implied) grafted into the true vine (Jesus) by  God, (the gardner) give the picture of the complete union of the branch & the tree?  The use of Gr.  μὴ (not) in "not bearing fruit"  signifies the fault is with none other than  the branch itself, and this will shed a new light on  what Jesus really  means "cut of....dried... throw into the fire.. to burn."
Comment: If a branch was in complete union with the tree then why would the gardener choose to cut it off? If the tree is trying to produce fruit through a branch and the branch won't produce any, the gardener would then cut it off so another can take it's place. So in effect the Branch that was cut off was never in union with The Tree, since it did not yield the fruit that The Tree commanded it to. Cutting the branch would be the idea of The Holy Spirit being removed due to it not living in The Person, "I Never Knew you" Knew here from what I've heard is a Spiritual Intimacy. (Becoming one)
Comment: It is natural that physical branch bears fruit when grafting is done. However, "human" branch though they are in union with Christ (grafted) has to yield to Him, and in obedience to His Word and to Holy Spirit, should continue walk the walk and live out the Word.  Notice the Jesus' words that disciples  to abide in Him  and His Word to bear fruits pleasing to Father God.
Comment: this would fall into The Free Will debate? if weather or not someone can choose Christ or like How he says to The Disciples "You did not choose me but I choose you" but we would be here forever talking about that lol. The example of some1 from The OT that I would use who Had The Spirit then lost it was Saul, but it always was In God's will to replace Saul with David (since through David Jesus would come) wouldn't we see modern day examples like Saul with the Wolf in Sheep's clothing? They have the appearance of The Sheep, but they're not a true Sheep, because The Spirit does not live in them.
Comment: Jesus speaks in the parable of the responsibility of "branches," which the farmer (Father God) elected and grafted into the True Vine(Jesus), to remain in union with Jesus ( = He is you, I in you; My word abide in you, you keep my words, etc) and bear fruit to please the farmer (God, the Father). NT has two example, one, the "wolf in the sheep skin-you mentioned, and Paul to elders of Ephesus, on his way to Jerusalem, said " Even from among your own group men will arise, teaching perversions of the truth to draw the disciples away after them." (Acts 20:30, who were true sheep turn into bad.


Can be used pwa as a desktop rwd website simultaneously?

Question: I want to create a web application. Before knowing about pwa, i wanna to create my wep app with rwd(responsive web design) that implements by react.
I don't want to have two seperated url and site for pwa and desktop. What could i do? Can i use serviceworker and manifest in root of my rwd design ? When users go to url in mobile, they see pwa and in desktop they see rwd. Just with one url. Thanks.
Answer: Yes service workers and manifest will help you accomplish this. The pwa will be from the Responsive Web Design, meaning you Progressive Web App is linked to the rwd.
See explanation:  https://www.optasy.com/blog/3-essential-steps-convert-your-website-progressive-web-app


What is the command or hotkey for stopping a running program in DrJava?

Question: I installed DrJava about a week ago. Its been working fine so far but I ran into an infinite loop and wanted a way to stop the program from running without having to force DrJava to quit. Is there a command or hot key that would enable me to do so?
Answer: To shut any command line program just type Ctrl+c.
It will look like this on the command line : ^C
This is called an escape sequence.
EDIT
I think you may be able to use Ctrl+D or ^D also
Answer: There is a "Reset" toolbar command to the right of compile.  That will stop the running program in Dr. Java.


Making my own Jewish calendar with paper and pencil

Question:
I would like to make my own Jewish calendar on paper with pencil ( using the help of programming for the more difficult  calculations, ofcourse). How and where do I begin.

Who makes the annual Jewish calendar? Who exactly checks to make sure that all the leap years, etc are added as they are supposed to. Is there a "Hashgacha/ Mashgiach" for the calendar?
Comment: There are multiple programming implementations: [python](https://github.com/pinnymz/python-zmanim), [java](https://github.com/KosherJava/zmanim), [nodejs](https://github.com/hebcal/hebcal-es6), and [c](https://github.com/hebcal/hebcal).
Answer: There's no need for a mashgiach since anyone can check on their own. Here's all you need to know to calculate any date.
In years whose value is 0,3,6,8,11,14,17 modulo 19 an extra month is added after Shevat with 30 days.
The "molad" (new moon occurrence) of Tishrei of year 1 was 5 and 204/1080 hours into the second day of the week. Every subsequent molad happens 29 days and 12 and 793/1080 hours later.
Rosh Hashanah for a given year is the day its molad falls, unless pushed off by one of the following four rules. 1) Rosh Hashanah would be the first, fourth or sixth day of the week, 2) the molad is 18 hours or more into the day, 3) at the start of a non-leap year, that number for the third day of the week is 9 and 204/1080 hours into the day, 4) when following a leap year, that number for the second day of the week is 15 and 589/1080 hours.
The non-leap months alternate lengths between 30 and 29 beginning with Tishrei, but you should add a 30th day to Marcheshvan or remove the 30th day of Kislev as necessary to ensure the right number of days exist between Rosh Hashanah of one year and the next.
Comment: It shouldn't be surprising that this can all be done by hand, since that's how everyone did it until quite recently.
Comment: related https://judaism.stackexchange.com/a/23306/759
Comment: What is "that number for the third day of the week"? Is it the number of hours the molad falls into the day if it falls on day 3? Also, "into the day" means counting from when?
Comment: @magicker it means instead of 18 hours as in rule 2, it's 9+ or 15+ hours into the day. How to translate these times to real times is unknown and don't believe anyone who tells you they know how, but the basic theory is to count forward from average sunset so something like 6pm (thus 18 hours is noon etc)
Comment: Fairly significant edits, possible to add your sources?
Answer: For a detailed walk through the process, for 5780, here's my youtube presentation: https://www.youtube.com/channel/UC8L25iBp_ZUias3gnvtFJTA
Here is a page about it which includes a powerpoint for this year (5784), and contains a folder available of the apps used: https://sites.google.com/site/miyminimichoel/home/this-years-calendar
Comments welcome.
Comment: Great presentation. I checked the website and a lot of your links no longer work. at least one required permission to view. may be worth checking the links in a browser where you're not logged in.
Comment: Will do. Thank you.
Comment: Should work now. Remember to extract the zip folder into a regular folder.
Answer: My father,the tzaddik nistar Harav Shraga Feivel ben Chaim Yehudah , made his own calendar using the Rambams rules as written in the Perush L'Mishnayos, when he was exiled to Siberia in 1939 at th age of 20. I thought it looked like our tradiitonal calendars. What a mistake. It was a strip of paper with the rules written on the bottom, the years running alongside vertically , and the hebrew dates of all the yomin Tovim next to each year. Interestingly, he had no idea when the Churban would be over, so he ran it to 2011, the very year he was Niftar. Tzaddik Gumer. Shochet with 3 smichos before he was 18, built Mikvah in Toulosue France in 1948, still there, made Kosher meat and chicken and learned 5 hours a day while working in USA. Zatzal.


Can the Kirisame no Jutsu extinguish the flames of Amaterasu?

Question: In Naruto Shippuden episode 147, a technique used by the ANBU forces of Kirigakure called Kirisame no Jutsu made rain fall down that absorbed chakra, and dissolved Naruto's Rasengan,  Utakata's Soap Bubble Ninjutsu and Sai's Ninpo: Choju Giga. Considering Amaterasu can't be extinguished with water, but this water absorbs chakra and other people's techniques, can the Kirisame no Jutsu technique extinguish the flames of the Amaterasu?
Comment: Going purely based of theory, any technique capable of absorbing chakra can ideally extinguish the Amaterasu cause the jutsu itself is a form of chakra. I tend to skip fillers so have no idea but one thing i can say tho is it might depend on the rate of absorption compared to how much of the flames burn out the water i guess
Answer: This is unknown.  This jutsu has never canonically been applied against Amaterasu, so there is no way to either affirm or rebut claims on either side.
Answer: As @Rumpelstiltskin mentioned in the comments,

any technique capable of absorbing chakra can ideally extinguish the Amaterasu cause the jutsu itself is a form of chakra.

Amaterasu can practically only be stopped, if one, sealed, as Jiraiya did. Or, if absorbed. It will also extinguish if it passes its time limit of seven days and seven nights.

Amaterasu cannot be extinguished but sealed.

Taken from Quora page: What would Jiraiya do if Amaterasu hit him?
And, Amaterasu can also be defeated by absorbing jutsu, as Madara has shown when Sasuke cast Amaterasu on him. Although most of the flames were concentrated to his armor, he managed to remove it by taking his armor off and absorbing the rest of the Amaterasu with the Rinnegan's Preta Path.
The wiki also explains that:

The Preta Path (餓鬼道, Gakidō) grants the user the ability to absorb chakra in any form. ... This ability is primarily defensive in nature as it is capable of absorbing chakra from an individual through physical contact. (emphasis my own)

Any jutsu that can absorb jutsu ideally can absorb jutsu / dissolve any justu should be able to absorb Amaterasu, whether the technique used to dissolve the jutsu is made of water would not be much of relevance, as it can still absorb jutsu. Thus, it is likely that the Secret Technique: Mist Rain can absorb/dissolve Amaterasu.
But as @Makoto mentioned in his own answer, this jutsu has never been applied to Amaterasu canonically, but in theory this should be possible.

Sources:

What would Jiraiya do if Amaterasu hit him?

Naruto wiki article on Preta Path

Naruto wiki article on Secret Technique: Mist Rain
Comment: I believe there are other methods of tackling Ametarasu apart from Preta path. You can use Shinra Tensei to push away the flame, use Kamui to transfer the flame to other TS dimension or be a jinchuriki (they are unaffected by Ametarasu). I also think Jiraiya knew a [fire sealing technique](https://naruto.fandom.com/wiki/Fire_Sealing_Method) to seal Ametarasu.
Comment: @FumikageTokoyami That *is* true, thanks for the additional info!


Restart IIS Admin Service or Recycle Default App Pool?

Question: A weekly maintenance process requires stopping ArcGIS Server and ArcSDE services. After restarting all the services, is it better to restart IIS Admin Service or recycle Default App Pool? I currently run a python script to do the later, with inconsistent results.  Sometimes it takes 2 or 4 attempts, or stopping and starting AGS and ArcSDE services again, to get the web services working.  I'd like a clear procedure that will work each time.
Answer: Restarting the IIS admin service just puts more steps into the restart process for IIS.  It may make things easier for you, but I would recommend a more careful restart:

After stopping ArcGIS Server and ArcSDE, wait until the SOM, SOC, giomgr and gsrvr processes have ALL stopped.  The Stop Service command should wait for them, but they might not respond to the stop command.
Any processes that are still going after you've stopped the service need to be terminated.  Otherwise the startup process will get confused and may try to attach those dying processes.
Make sure your database is up and running ("hot") when you start ArcSDE.  It needs the database to get its license.
Start ArcGIS Server after ArcSDE.
Recycle the app pool.

Restarting IIS Admin service would be fine, but if your server also has FTP or SMTP services running through IIS they will be brought down too.  Recycling the Default App Pool (and any other pools that run your maps!) should be adequate.
Answer: Recycling your application pool does not immediately kill the worker processes - it waits for them to complete, or for the timeout period to expire. This would be the reason why they would still be running after a few attempts to recycle.
It will however eventually restart all processes (and without suddenly cutting someone off).
In IIS7 you can see the requests that are still running by clicking on the Worker Process icon in IIS manager, and then double clicking on an individual process.


Does DFW have moving walkways in any terminal?

Question: I didn't see any moving walkways in DFW in Terminal C. Do they have any in any terminal? Seems like they ought to for an airport of it's size but maybe not..
Comment: Perhaps expand your question to all walk-free options in DFW? I'm sure there's something like a free shuttle for those with disabilities.
Comment: I took one there last year.  It was a private flight from KSEP to DFW and sadly I do not remember the terminal (or I would give an answer).
Comment: @JonathanReez - I think it does have carts that employees drive around but I was curious specifically about moving walkways. Personally, I think it could benefit from them if it doesn't have them but whatever lol
Answer: There is a photo of walkways in the google map gallery, which shows a 360° view with a DFW sign visible.
https://goo.gl/maps/VELoZojtUZJ2
Judging from the escalators at either end of the walkway, this appears to be beneath the tarmac and used to connect between two terminals.


Magento2 cms page display 404 via mysql query import data to cms_pgae

Question: In Magento CE 2.4.5, I imported the page data in the cms_page table by sql, and 404 appeared in the access address. What should I do if the page cannot be found
Answer: I think you have not imported the data correctly.
CMS pages data resides in two main tables, i.e. cms_page and cms_page_store.
In order to fix the problem, you would need to import data of both tables correctly.
Also, you need to make sure that after importing, cms_page_store has the correct value of page_id corresponding to the cms_page table.
Answer: For importing cms_page data best way to collect sample data(or export) make the changes and import the same file.
Two tables are where your data shall go :
cms_page :
page_id smallint Auto Increment Entity ID
title   varchar(255) NULL   Page Title
page_layout varchar(255) NULL   Page Layout
meta_keywords   text NULL   Page Meta Keywords
meta_description    text NULL   Page Meta Description
identifier  varchar(100) NULL   Page String Identifier
content_heading varchar(255) NULL   Page Content Heading
content mediumtext NULL Page Content
creation_time   timestamp [CURRENT_TIMESTAMP]   Page Creation Time
update_time timestamp [CURRENT_TIMESTAMP]   Page Modification Time
is_active   smallint [1]    Is Page Active
sort_order  smallint [0]    Page Sort Order
layout_update_xml   text NULL   Page Layout Update Content
custom_theme    varchar(100) NULL   Page Custom Theme
custom_root_template    varchar(255) NULL   Page Custom Template
custom_layout_update_xml    text NULL   Page Custom Layout Update Content
layout_update_selected  varchar(128) NULL   Page Custom Layout File
custom_theme_from   date NULL   Page Custom Theme Active From Date
custom_theme_to date NULL   Page Custom Theme Active To Date
meta_title  varchar(255) NULL   Page Meta Title
and
cms_page_store :
page_id smallint    Entity ID
store_id    smallint unsigned   Store ID
So important things :
in cms_page_store table there is a mapping between Store ID and page ID. Do check they are there.
in cms_page : make sure that Identifier and is_active is properly imported.
plus page id relates to cms_page_store
As these are pretty small tables and not complex I feel this is the faster way to debug and fix.


What can I do when I receive a 'server-error-not-accepting-jobs' CUPS server error in 11.10?

Question: I have a Richoh Aficio-CL3500N that I connected directly to the USB port and it seemed to add and configure itself and populated all fields in 'Printer Properties', but I received the error 'server-error-not-accepting-jobs'.
Answer: I actually figured this out while asking the question...
What I did to correct this was to go to 'Printer Properties > Policies > State' and checked both the boxes for 'Enable' and 'Accepting Jobs' and then that corrected the problem I was having.
Answer: Click on "Accept Jobs" in the printer's section on http:// localhost:631 (in the first drop-down selection)
Comment: For those who only can access printers from command line, can run `accept `
Answer: anytime I go to localhost://~~~631/Printers  in CUPS;  I can see the printer;  but if I try to edit the printer in any way I am prompted for Username/Password.
Even if I load the browser as SUDO/Root  I still get this error.
Linux Mint has username lampp  and password admin for CUPS and OpenERP ;  or admin /  123  for other things, it also has an xampp password.   anyways I tried ALL Live CD passwords and none of them worked.
I tried the Printer GUI;  and was able to print to it via "Postscript driver"  but it took forever and only printed half the test page.  None of the other drivers work.  Keep getting CUPS Server Error.
***Funny thing;   I loaded KUBUNTU; it saw the printer and installed it with ONE CLICK!!!
Puppy Linux installed it with a little Jet Direct command line... socket://192.168.printeraddress port 9100;
gutenprint driver also hangs then fails.
I went to Brother Site;  Downloaded the CupsWrapper Driver and the LPR Local Driver;  you don't need command line just double click on the downloaded .deb file and the package manager will install it;  it then recognized the printer and installed it.   dnssd://Brother%20MFC-L2740DW%20series._ipp._tcp.local/?uuid=e3248000-80ce-11db-8000-30055c9af64a   on LocalHost.
It even notified me I need to change my Print Heads Soon.
HOWEVER;  it will STILL NOT Print a test page !
Linux Mint...WON'T WORK no matter what I try.
The Error has something to do with CUPS Admin settings, and allowing the printer to accept jobs. (even though it is set to allow Everyone to modify jobs) via   System Settings --> administration --> printer settings  ...
But Still it doesn't matter it simply wont print. Also through the browser I am BUSTED every time because I need the friggin password!!


GTA V Gold Medal objective unavailable

Question: Mission, Franklin and Lamar. Objective, deliver repo car with minimal damage. I have driven so carefully as to not touch anything, three times over. The objective is greyed out in the replay screen, and I know I've achieved it at least twice. Do crashes accumulate through retries, or what's going wrong here? Mission, complications. Objectives, complete in 5:00. I timed myself doing it in 4 minutes 37 seconds, once again, objective is greyed out in replay screen. What am I doing wrong here?
Comment: any cheats enabled/active? what platform?
Comment: If you could explain why you've timed yourself that would be helpful as I have checked everywhere and there's no time objective for this mission in particular. If you could also reply to @NicholasAysen so I can update my answer to be a little more in-depth response.
Answer: Damage to the cars should not prevent you from unlocking the gold medal via retries. It is possible you are damaging your car unintentionally. Hard landings will damage the bumper of the car and are difficult to avoid when driving over some of the bridges on the mission route. It is also possible that you encountered a glitch while playing the game.
In short there isn't really any other qualifiers to complete the challenge for this mission. The repossessed car was either damaged during the drive or your game is bugged.

GTA V Gold Medal objective unavailable


Does the programming language or database you use have any effect on the selling of your site?

Question: I was just wondering if the programming language or database you use has any effect on selling your site to another company? I mean is it easier to sell PHP site than other language? How about database type? If I was using Redis instead of MySQL, would that make any difference?
Comment: On auction? You mean as in selling a product through some sort of online (bidding?) systems, much like you have for web/layout designers can with their designs?
Comment: I took the word out. It was just distracting.
Comment: What do you mean by selling? Marketing, or like Htbaa asks, selling it as a product, or maybe as a code base to someone else.
Comment: Selling the whole site to another company.
Answer: I think its a consideration, but a secondary one. If the site is valuable enough to the customer, then they will buy it regardless of the technology used. That said, unless you plan on supporting that site into perpetuity, it is probably a good idea to use a more commonly used web programming language, like PHP, Python, or Ruby. Otherwise, it will be more difficult for the purchasing company to find programmers to maintain that site after you're gone.
Answer: I guess it would depend on who you're selling it to. Clients, especially ones with little technical expertise, can be prone to trendy buzz words as everyone else. I once had a client who wanted an ERP for his smallish company and wanted the back end to be Oracle, because a little bird told him that Oracle was "the best". Fortunately, one look at the licensing fees shut him up :D
Another, more legitimate, factor is if the client wants to staff the website from his own team. Having a website that runs the same technology that his team is familiar with would be a plus in his view. That being said, if the web site's perceived value trumps whatever additional cost the client would need to invest, then chances are good that the underlying technology wouldn't matter so much.
Comment: +1 It may not be THE deciding factor, but it's a factor. A company that's in love with Ruby and fully staffed with Ruby developers will value a Ruby-driven site more highly than a Microsoft shop that lives and dies by ASP.NET. That said, it shouldn't affect your decision when creating the site, because you're going to use the technology YOU like the most (for the task)...
Answer: No. The only thing that will matter is the number of visitors\ users.
Comment: Not necessarily true. If the site is coded in C++ it would definitely be helpful to know that and it may discourage some from bidding/buying as the buyer may not know C++ (but may know PHP, for instance)
Comment: @Cory: Even then, it *might* matter.
Comment: If the buyer is concerned about the technology, the site has no value and\or buyer has no money.
Comment: @Jetti I am not taking about extreme case where coding the site in C or assembly. Just common web programming languages such as PHP, Python, Ruby,...


Home and End keys stop working correctly

Question: I am running a session of emacs in an xterm+256color terminal, i.e., with the command emacs -nw. At the start of my session, the Home and End keys work just fine. However, after a while, the Home key eventually starts producing the key code ^[[H instead of ^[OF. Why does this happen? What can I do to fix this problem?
Comment: Do you see this when you use Emacs without your init file (`emacs -Q`)? If so, try to isolate what you've done before the change happens. If not, recursively bisect your init file to find out what introduces the problem.
Answer: xterm has multiple keyboard modes (e.g. application mmode), and accepts escape sequences to switch between them. For example you can make the keypad send "1", "2" etc or you can get it to send sequences.
The simplest way to get it back to normal is to run 'reset' or 'tput reset', which will consult the termcap or terminfo terminal database and should output the correct escape sequences to put all the keys into a standard state.
To avoid the problem in the first place avoid using 'cat' on binary files and other sources of random escape sequences being output to your terminal which can change the modes.
Comment: Thanks, this was a fast way to fix the issue. I don't ever 'cat' binary files, so I'm not sure where the issue crops up. But at least I do not have to close out and open a new session to get things working with your fix.


Can't find "referenced string" in OllyDBG

Question: So I am trying to reverse a program and crack it but I am not able to find any of the Strings through searching for "referenced Strings" or "binary Strings", I am new to OllyDBG and I don't know a lot about it, which is why this is driving me crazy. I'd like to know how or where I can find the Strings then or if there is another method of finding a given Assembly Line where I could start.
Thank you already :)
Edit: If you need any more information, just ask and I'll deliver it.
Already asked in ReverseEngineering Stackexchange but it seems like nobody there knows or has the time to answer.
Answer: searching for All referenced strings only show you some function that push address of string but it cant find the address when calculate the address before.
here is a good idea:
press Alt + M and press Ctrl + B and search. it will find any string.
and then select the memory and use memory break-point for selected memory.
Answer: In OllyDBG it is not egal where you do the search. If you search in memory dum window, it will search in only one page. But if you search on memory pages window, it will run through all the pages looking for your string. Also, try searching for utf16 chars.
Answer: If you are in the right module Alt+E where the strings should be and you still could not find, the program could have hid it as an anti debugging measure, you may try to track it down by setting breakpoints on Symbolic Names Ctrol+N(which may be hid too) or try using the button method (which is very bad)

Can't find “referenced string” in OllyDBG


Finiteness of speed of light

Question: The postulates of the special theory of relativity say that there is a limiting speed - the speed of light. But this is a postulate. There are experiments confirming that the speed of light is approximately $3 * 10 ^ 8 m / s$. From what fact does the finiteness of signal propagation come from? All theories, whether it is special relativity or general relativity, confirm the postulate that the speed of light is finite, but in Maxwell's electrodynamics there is no limit on exceeding the speed of light. There, the magnitude of the speed of light is the constant of propagation of an electromagnetic wave in a vacuum as $\frac{1}{\sqrt{\epsilon_0\mu_0}}$. Lorentz transformations and, as a consequence, the incorrectness of the formula for adding the speeds of Hallei $v=v_1+v_2$ are also a consequence of the fact that the postulate of the special relativity declares that the maximum speed is the speed of a photon. If in the special theory of relativity it was said about the limiting speed as $2c$, then the Lorentz transformations would still be correct, but the maximum speed would be different.
Where does the finiteness of the signal propagation come from?
Comment: This post seems confused - you start by saying that this is a postulate, then say its empirical, then ask for a mathematical proof. What do you actually want to know?
Comment: Maxwell's equations for electromagnetism are covariant (i.e. invariant in form) under Lorentz transformations which are valid with limiting speed $c$. If the limiting speed would be $2c$ neither Lorentz tranformations would be correct nor Maxwell's equations would be covariant under them.
Comment: That's like asking why the mass of the electron is the value it is, isn't it?
Comment: TLDR: The postulate is that _light_ travels at the same speed in any coordinate frame. That came from Maxwell. The conclusion is that if _anything_ travels at a constant speed regardless of coordinate frame, then nothing _else_ in the universe can travel any faster. See answers, below, for more detailed explanation.
Answer:
The postulates of the special theory of relativity say that there is a limiting speed - the speed of light.

This statement of yours is incorrect. The second postulate of special relativity is-

The speed of light in free space has the same value c in all inertial frames of reference.

This postulate doesn't say that the speed of light is the highest allowed speed. But using this postulate we can get the Lorentz transformations. Then we define the momentum of a particle with mass m as- $$\bar{p}=\gamma m\bar{u}=\frac{m\bar{u}}{\sqrt{1-(\frac{u}{c})^2}}$$
The reason we define like this is if we define $\bar{p}=m\bar{u}$ momentum won't conserve. But the above definition conserves momentum. From using this definition of momentum we get the energy as-$$E=\gamma mc^2=\frac{mc^2}{\sqrt{1-(\frac{u}{c})^2}}$$
You can easily see that any finite energy cannot take a non zero mass m to the speed c. So no signals can propagate faster than c. If a particle has zero mass it should always travel at c and if its mass is non zero then its speed is always less than c.
Additional Note
If you are wondering why kinematical laws are connected to light, they really aren't connected much to light. If we replace the second postulate with-

There exists a speed b which is the same in all inertial frames of reference.

Then we can get the same laws of special relativity and we can show that anything which has 0 mass has to travel at the speed b (which coincides with c as photons have zero mass/rest mass). In fact, there CAN be other massless particles also, for example, the hypothetical Graviton is massless (Its existence is needed for String theories but not for Loop Quantum Gravity).
Comment: And if its mass is imaginary then it should always travel faster than c.
Comment: @user253751 well tachyons are hypothetical as of now, so neglected them.
Answer: The speed of light in vacuum is measured or like you said determined by maxwells law. The R.Th says it is  independent of the relative velocity of the light source, so one cannot increase it by starting from a moving source . This also can and is be proved by experiments. So how will you get to 2c?
Answer: The speed of light was known to be finite long before Einstein. As you point out, Maxwell figured it out from $\frac{1}{\sqrt{\epsilon_0\mu_0}}$. This was experimentally confirmed as invariant by the Michelson-Morley experiment, which led on to the Lorentz-Fitzgerald contraction and thence to Einstein's inspiration.
So really, you are asking why the permittivity and permeability of free space turn out to be the minimal values permissible.
Well, firstly, in every environment other than high vacuum they are higher. This is down to the nature of matter as charged particles and the way they interact with passing photons. Light goes fastest when there is nothing slowing it down.
But then, where do those limiting numbers come from? We might hope to find an answer in the zero-point fields of quantum field theory, the density of virtual particles and suchlike. But here we hit a famous discrepancy of some 120 orders of magnitude - we have not the faintest idea what is going on. We just pull the measured numbers out of the sky and plug them in, as Maxwell did.
Since we do pretty much that with well over a hundred similar fundamental constants and parameters, we don't worry about it too much.
Answer: Yes, relativity says there is a limiting speed, call it $c$ but don't give it a name at this point, and that gives the Lorentz transformations.
If you apply the Lorentz transformations to electrostatics, which contains $\epsilon_0$ to describe the force between charges, then you get magnetism, which
contains $\mu_0$ to describe the force between currents, and this shows that $\mu_0=1/(c^2 \epsilon_0)$.
That gives you Maxwell's equations, which turn out to have wave solutions, and the wave velocity of these EM waves is $1/\sqrt{\mu_0 \epsilon_0}$ which is $c$. At this point we can say "$c$ is the speed of light".
Answer: The speed of C (which is also the speed of anything that is massless (including light)). Is just a 45° angle in a spacetime diagram. It reveals and illustrates the relation between space and time.
Now that space and time are "connected" that "connection" is the speed of C.
And as the story goes, nothing can travel either faster neither slower than C, in spacetime.

Initially we thought that we were living inside a flat Euclidian spacetime. But experiments showed that maybe we are not. And the 1st confirmation of this was when we tried to measure the speed of something massless (like light) and we found that its speed was invariant.
So now we have a theory that changed our relativity, from the Galilean relativity that we had before, to the Einstein relativity that we use now, where spacetime is not Euclidian but hyperbolic.
In such a spacetime velocities in space and time are both relative and the way they are related is called the Lorentz factor which includes the speed of C in it.
In such a hyperbolic spacetime, the speed of light is effectively infinite.
By effectively, I mean the following:
If you are traveling at the speed of light, you would be able to travel ANY distance at ANY time. You could travel at some distant star that is 500 million light years away, in ZERO time - not because you were indeed traveling that fast, but because you simply didn't experienced any time.
Ofcourse it did took you 500 million years to reach that star - but you just didn't experience those 500 million years. To you, that trip looked instantenous.
Those 500 million years did pass, you just didn't experience them. That is the idea behind [proper velocity][1]
$${\displaystyle {\textbf {w}}={\frac {d{\textbf {x}}}{d\tau }}}$$
It is an alternative to ordinary velocity, the distance per unit time where both distance and time are measured by the observer.

Now in Galilean relativity, indeed the speed of light was thought as infinite, but also, Galilean relativity preserves causality by having a fixed and invariant speed for time.
Everything including light, (in Galilean Relativity) is traveling in time at 1s every second... So If we call that speed in time λ then $$ λ= \frac{1s}{s}$$
and thus λ is a constant and invariant speed.
But ofcourse back then, nobody questioned why λ was constant or invariant, because it was obvious (although not anymore) that if we were to synchronize our clocks, and you get in a Ferrari and drive away - when you come back our speeds would still match... So everything is moving towards the future at the speed of λ which was our philosophical idea about the reality that we were living in, the idea that by having a constant and invariant speed for time, would preserve causality.
Einstein's Relativity has a diffrent constant and invariant speed that also does the same job, preserves causality. That speed is not a speed in time, (because now speeds in time are relative) but a speed in spacetime. And that speed is C.
And C is a speed that indicates that there is a relation between space and time. That relation is give by the Lorentz factor γ
$${\displaystyle \gamma ={\frac {1}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}={\frac {1}{\sqrt {1-\beta ^{2}}}}={\frac {dt}{d\tau }}}$$
In relativity, you can go as fast in space or in time as you want, as long as, when your speed in time and space are combined they yield C. So our speed in spacetime is always C.
The finiteness of the propagation of light, comes from our "struggle" to preserve causality inside a hyperbolic spacetime like the Minkowski one that Einstein's relativity is using.
If anything was to travel in spacetime faster than C, (even light) then causality wouldn't be preserved. The same ofcourse happens if anything was to travel in spacetime slower than C.
C is not just the speed limit in spacetime, its the ONLY SPEED allowed in spacetime and nobody can go slower or faster than it.
But ofcourse as I showed above, since time and space are relative, we can effectively travel "faster than C" because there will be a huge amount of time that we wouldn't experience. But that will only apply to those who measure speeds incorrectly. Once we measure one's speed correctly (taking into account both his speed in space and time) then everything in the Universe travels at C in spacetime.
Edit: I don't understand why people downvoted this post. Nothing of what I said is wrong and they illustrate perfectly the core ideas of Einstein's relativity. I wish people would at least tell me why they are downvoting this :/ I'm ok if you downvote me, but please at least tell me why.

Finiteness of speed of light


Community Wiki links

Question: I understand that there is a Community Wiki, but I've never found it.  Where would I find a link to take me there?  Is there a way that we can have a more obvious connection to the CW page?
Answer: Community Wiki isn't a specific page; it's a status.  Posts that have been edited a lot,1 and questions that attract a lot2 of answers, are treated as community-owned and are automatically set to CW.  This change allows anybody to edit (bypassing reputation requirements).  It also ends reputation changes for the original author, as it's now treated more as the community's post than the author's post.
An author is able to designate a post as community wiki from the start to invite this kind of participation.  We've seen that a few times, often for posts that seek to compile a list.
Tag descriptions are also called "wikis", by the way, and like CW posts have no single owner.  (There are reputation requirements to edit tag wikis, but anybody can propose an edit.)
1 Ten edits, or edits by five different people, kick a post into CW.  (I'm doing this from memory so while I think those are the right numbers, I could be wrong. But if so, it's close to that.)
2 A question that attracts 30 (or is it >30?) answers becomes CW; the question and all its answers acquire this status.
Answer: You can limit your site-wide searches to CW posts using the string wiki:yes (or wiki:no for the opposite effect) in the standard search bar.
Eg: https://judaism.stackexchange.com/search?q=wiki%3Ayes+bracha
You can find out more about Community Wiki posts in our help center or in the MSO FAQ.
Comment: Oh, oops.  I sure wish there were a "somebody else is composing an answer while you are" indicator. :-)
Comment: @MonicaCellio That's a known issue :) It's ok. I think our answers compliment each other well. +1 to you
Comment: Yours is the better answer in that it teaches how to fish instead of giving fish.  (And yeah, I know there's a feature request on MSO somewhere for that.)

Community Wiki links


EEA pre settled status marriage and retained rights

Question: If a third-country citizen marries an EEA national in the UK with pre-settled status in 2022. What visa will they apply for. And what about retained rights after 3 years rule? Will this policy continue for new couples after 2022 or not?
Comment: Please do not vandalize your posts. By posting on the Stack Exchange network, you've granted a non-revocable right for SE to distribute that content (under the CC BY-SA 3.0 license). By SE policy, any vandalism will be reverted.
Comment: If you think you may not want people to be able to see your question in the future, don't post it in the first place. Vandalising it doesn't make it disappear, it is of course still visible to everyone with access rights to edited posts, and is likely to be reverted. Plus users may be less inclined to bother to answer further questions you may post.
Answer: Under the terms of the Withdrawal Agreement only relationships established before the end of the transition period open special rights for members of the family of an EEA citizen. However, marriage is not the only type of relationship that's relevant so if the couple had formed earlier, the spouse might still qualify for an easier visa on the basis of this "durable relationship".
All this is detailed in article 10:

Personal scope

Without prejudice to Title III, this Part shall apply to the following persons:

(a)  Union citizens who exercised their  right to reside in the United Kingdom in accordance with Union law before the end of  the transition period and continue to reside there thereafter;
[…]
(e)  family members of  the persons referred to in points (a) to (d), provided that they fulfil one of the following conditions:
(i)  they resided in the host State in accordance with Union law before the end of the transition period and continue to reside there thereafter;
(ii)  they  were  directly  related  to  a  person  referred  to  in  points  (a)  to  (d)  and  resided  outside  the  host  State  before  the end  of  the  transition  period,  provided  that  they  fulfil  the  conditions  set  out  in  point  (2)  of  Article  2  of  Directive 2004/38/EC  at  the  time  they  seek  residence  under  this  Part  in  order  to  join  the  person  referred  to  in  points  (a) to (d) of this paragraph;
[…]

Without prejudice to any right to residence which the persons concerned may have in their own right, the host State shall,  in  accordance  with  its  national  legislation  and  in  accordance  with  point  (b)  of  Article  3(2)  of  Directive  2004/38/EC, facilitate  entry  and  residence  for  the  partner  with  whom  the  person  referred  to  in  points  (a)  to  (d)  of  paragraph  1  of  this Article  has  a  durable  relationship,  duly  attested,  where  that  partner  resided  outside  the  host  State  before  the end  of  the transition  period,  provided  that  the  relationship  was  durable  before  the  end  of  the  transition  period  and  continues at  the time the partner seeks residence under  this Part.

Regarding marriage, note that tarticle 10(1)(e)(ii) reads "they were related", i.e. the marriage must have existed before Brexit. It's only in that case that EU freedom of movement rights can cover a spouse who wasn't already present in the UK, which means someone marrying in 2022 wouldn't be covered by this provision.
The same logic applies to point (4): Only a relationship that qualified as durable before the end of the transition period can be invoked. It could however be useful if the two spouses were already in a relationship long before marrying. On the other hand, if their relationship started after Brexit or even shortly before, the only option left would be the regular UK immigration rules.
Comment: If the relationship would have qualified as a "durable relationship" on or before the end of the transition period, the couple ought to be able to apply on that basis. It wouldn't make sense for the marriage to reduce the rights derived from the relationship: https://www.gov.uk/settled-status-eu-citizens-families/eligibility.  Also, there are some people for whom the June 30 deadline does not apply, though it doesn't seem that any of these cases is likely to apply here: https://www.gov.uk/settled-status-eu-citizens-families/join-EU-EEA-Swiss-family-member
Comment: @phoog That's true, it's actually covered in the same article (point 4 further down) but I discounted it because I was focusing on the fact that the relationship described in the question (the marriage) was established after the end of the transition period. You're obviously absolutely right that someone marrying in 2022 may very well have been in a durable relationship for some time before that. I will rephrase the answer.


How to create an asio socket with an existing fd and callback into custom code rather than read from it when data is available

Question: I have a C++ application where I'm using a 3rd Party api. As part of that api they will handle the socket connections etc, however, they have a mode where I can select / poll on the fd and then call into the api read from the socket, decode the data and dispatch to the proper handlers; this way we can control the thread where the dispatch code runs. Now I also have extensive use of asio for my networking and I would like to handle this with that. In fact, I desire the api's dispatch code to run on in the asio thread. So, I would like an asio socket that takes the existing fd and then makes a call to what I want when there is data on the fd. This seems pretty straight forward but I can't find it in the docs / examples.
Answer: For sure this depends on what asio framework your are on.
In my libevent-based framework  , I implement the operation like this
void BaseConnection::take_socket(evutil_socket_t fd, short event_mask, int options)
{
    this->bev = bufferevent_socket_new( get_event_base(), fd, options);
    if (!this->bev) {
        throw SimpleException("Error constructing bufferevent on fd #%d", fd);
    }

    bufferevent_setcb(bev, trampoline_readable, trampoline_writable , trampoline_event , (void*) this);
    bufferevent_enable(bev, event_mask);
}

After take_socket gets called, fd would be taken by a buffered event (this->bev),
and when income data available, trampoline_readable will be called.
If you are on boost::asio, though I am not familiar on it, you may have interest on basic_stream_socket::assign.
Good luck:)
Answer: I found what I needed, asio::posix::stream_descriptor. I can assign it the socket handle (fd) and then call async_wait and asio will notify me when there is data to be read:
    descriptor_.assign(connection_.get_socket_handle());
    descriptor_.async_wait(asio::posix::stream_descriptor::wait_read, [this] (const std::error_code& error) { this->handle_data(error); });


pt cruiser 2.2 crd 2003 coolant bleeding

Question: Does anybody know if its necessary to bleed air from cooling system after thermostat replacement in this car ? If so does anyone know a correct procedure to do so ?
Answer: All cooling systems need to be bled of air when they are filled.
On your vehicle, there is a bleed valve just below the thermostat housing.

This needs to be open as you fill the cooling system to allow air to escape. Once coolant begins to flow through the bleed valve, close it and top off the system from the overflow tank.
In the event you get some erratic temperature readings or no heat, you may need to reopen this to allow any residual air to escape.
WARNING: Do not open hot cooling systems as is can result in injury.


dBFS and dBSPL unit

Question: Hi I've recorded sound(field sound) using six microphones with sensitivity 5mv/pa  by zoom recording device the results were obtained by dBFS unit and  i need it in dBSPL, Is there any way to convert it?
because I have read several articles and come to the do not directly convert between the two units and need to calibrate the device and determining the gain, but I recorded directly without doing anything .
Another question whether the output values of positive values and negative do it represent the pressure deviation? I'm sorry but I do not have sufficient knowledge with the sound recording instruments.
 thanks
Comment: Quite a disconcerting read. You want to convert between to "units" when you in fact have two different physical quantities on hand. Ask yourself what dB SPL is (what physical quantity it is) and how your recording relates to that.
Answer: Unless you calibrated the microphones AND the recorder at the time of the recording the absolute dB SPL reference is lost and unrecoverable.  The reason is that you don't know what what the REAL sensitivity of the microphones are. "5mv/pa" is only the nominal design target. It does not necessarily represent the ACTUAL sensitivity. And only calibrated instrumentation microphones have a known and reliable SPL to voltage output ratio.
Furthermore, you used some unknown amount of gain in the recorder. So even if you had calibrated microphones, you would have no reliable reference unless you calibrated the microphone preamp gains and the recording levels.
Comment: We don't know what exactly the problem is?  WHY do you need dB SPL?  Can you explain the situation more completely?
Comment: If you were not using a Sound Pressure Level Meter, there really is no way to go back and "calibrate" your recordings. The major unknown is the recording volume control setting.  Unless you know that, there is no realistic way to correlate the recorded level with the actual SPL.  Can you repeat the experiment with a proper SPL Meter?
Comment: Thank you for your answer, but now what should i do? any suggestion to help me to solve the problem @Richard Crowley
Comment: I need to calculate the noise for the graduation project and in all the equations we need sound pressure level (dBSPL), but at first I did not know the difference between the two units and I need more than one microphone so used six microphones with Zoom recording device and the result in dB full scale.
Comment: If repeated the experiment How can I do calibration
Comment: I added a second answer as what you asked for will not fit within a comment.  And the SE mechanism discourages extended dialog in the comments.
Answer: You could try to go back and retroactively "calibrate" your original recordings. But that requires these things.

FIXED RECORDING LEVELS  Your original recording must have been done at some FIXED and unchanging recording level/gain from beginning to end. If you changed the recording levels at one or more points during the recording, then you have no way that any of the next steps will make any sense.  Note this includes using any kind of "automatic gain" as that completely destroys your data.
REFERENCE SOUND  You need some sound that was captured in the original recording which you can RELIABLY REPRODUCE.  That gives you the "link" between your original recording and something that you can actually MEASURE.
SPL METER  You need an actual, calibrated SPL meter. There is no substitute for this if you want believable SPL data.
CALIBRATED REFERENCE MEASUREMENT  Reproduce your "reference sound" and measure the SPL with the calibrated SPL meter.  Then you can use that peak level to measure against your recording levels.
Comment: Sorry but I did not understand some of the paragraphs clearly do you mean  record  a fixed sound level  like a sine wave and then re-run the recorded section and measure the SPL by calibrated SPL meter???

dBFS and dBSPL unit


What is the difference between 'same', 'typical' and 'similar'?

Question: What is the difference between same, typical and similar? All of them seem to convey the same meaning.
Answer: Actually they convey different meanings, though similar.
Same: exactly alike, identical: the same dress
Typical:Showing the qualities, traits, or characteristics that identify a group or class:  a typical suburban community.
Similar: alike though not identical: a similar look.
Answer: Same: "Justin wore the same shirt that Alice did" implies that Justin wore the exact thing that ALice wore, not just a shirt that looked like the one Alice had worn.
There is just one shirt under consideration here.
Typical: characteristic (adj.) "Justin wore a shirt that typically Alice wears" implies that Justin wore a shirt that was the kind of shirt that Alice has been observed to wear most of the time.
There are two shirts under consideration here.
Similar: looks/ feels akin (to something). "Justin wore a shirt similar to the one Alice had worn" implies that Justin's shirt looked like Alice's shirt. Note that the shirt could belong to the same company, but the shirt itself isn't the same, as both of them have their own individual shirts (that perhaps look ditto)
There are two shirts underr consideration here.


Solve multivariate equations in MATLAB/MAGMA/GP-PARI/SAGE

Question: I want to solve equations of the form
$$a_1 x_1 + a_2 x_2 + a_3 x_3 + \dots + a_n x_n + b_1 x_1 x_2 + b_2 x_1 x_3 + \dots + b_n x_{n-1} x_n$$
where all the coefficients are in $GF(p)$ and variables are binary.
Can you please tell me how do I solve this using MAGMA/MATLAB/SAGE/GP-PARI?
Thanks in advance.
Answer: Working with multivariate and nonlinear polynomials, I'm not sure there is much built-in functionality to solve these.  Of course, if there are not too many variables, you can just write a loop over the $2^n$ possibilities for the variables and check if each $n$-tuple is a solution.  In Magma you can hard-code in your polynomial as a multivariate polynomial over $\mathrm{GF}(p)$ and then evaluate at each possible $n$-tuple of values for your variables.
I'm not sure your level of expertise in any of these languages, but in Magma for instance, it could be done in maybe five lines of code.
Answer: I've never used sage but see: sage groebner
To make a variable Boolean add the equation $x_k(1-x_k) = 0$


Disabling IPV6 firewall with IPV6 disabled

Question: Our router (Asus RT-AC68U) has been slowing down our speeds, up until I disabled the IPV6 firewall (Went from 250 to 380, which is the modem cap for now). We've always had IPV6 disabled on the router, but I was wondering if it poses any security risk by also disabling the IPV6 firewall.
Answer: If the device cannot speak IPv6, then it is very unlikely that having an IPv6 firewall enabled would offer any protection.
Answer: The risk is that once you add a device that uses IPv6, you won't have protection. Leaving the protection on covers you when you make changes to the network, and you don't have to remember that you turned a protection off.
If the router simply won't process IPv6 packets, then that's a layer of protection, until you turn it on to allow an IPv6 device.
How much of a risk that might be to you is something only you can determine.


Converting Model in Plug-in in QGIS

Question:
Recently, I started making a model on QGIS and now I want to transform it into a plug-in, but it seems that I have to change the code to do it, otherwise it won't work.

What changes are required to perform this conversion?
Answer: To create a plugin from a model, use the "Plugin Builder" plugin.
By following THIS tutorial, you can build a basic structure.
On the third screen for plug-in creation, define the template as Process Provider. The model conversion is easier in this mode.
You will not need to use QT Creator or compile.bat described in the above link tutorial.
After you create your empty plugin, export your model as a Python script using QGIS version 3.6 or higher.
Save the created script.

In the folder where it was created the empty plugin, there are 5 basic files that should be edited. Keep the others as they are.
If your plugin has only one function, edit only the fourth file, use the default lines as examples:
This is a example of a plugin with 2 functions.
1- PluginNAME.py
You need to create a class for each function (model) that will be displayed, simply change the class name and self.provider in initProcessing.
class NewModelPlugin(object):

    def __init__(self):
        self.provider = None

    def initProcessing(self):
        self.provider = NewModelProvider()
        QgsApplication.processingRegistry().addProvider(self.provider)

    def initGui(self):
        self.initProcessing()

    def unload(self):
        QgsApplication.processingRegistry().removeProvider(self.provider)

class Model2Plugin(object):

    def __init__(self):
        self.provider = None

    def initProcessing(self):
        self.provider = Model2Provider()
        QgsApplication.processingRegistry().addProvider(self.provider)

    def initGui(self):
        self.initProcessing()

    def unload(self):
        QgsApplication.processingRegistry().removeProvider(self.provider)

For example, the Buffer by Percentage plugin has two functions, so in it's code there are two classes.

2- __init__.py
This file references all Classes created in the previous file, create a new block for each function.
    from .PluginNAME import NewModelPlugin
    return NewModelPlugin()

    from .PluginNAME import Model2Plugin
    return Model2Plugin()

3- PluginNAME_provider.py
Indicates which algorithms will be loaded. In import, list all comma-separated algorithms. In loadAlgorithm, enter all, one on each line.
from qgis.core import QgsProcessingProvider
from .PluginNAME_algorithm import (NewModelAlgorithm, Model2Algorithm)

class PluginNAMEProvider(QgsProcessingProvider):

    def __init__(self):
        QgsProcessingProvider.__init__(self)

    def unload(self):
        pass

    def loadAlgorithms(self):
        self.addAlgorithm(NewModelAlgorithm())
        self.addAlgorithm(Model2Algorithm())

4- PluginNAME_algorithm.py
Here will be the code of each algorithm.
Initially you need to import all libraries that all algorithms will use. QGIS automatic conversion creates almost all,
you will know which ones are missing when trying to run.
Create a class (QgsProcessingAlgorithm) for each desired algorithm.They are independent of each other, so each must have its own variables and parameters.
It's in this file, in each class, that you define the displayed name, system name, description, and icon displayed in QGIS.
Replace everything from Class (line 41 by default) with the Class contents of your script generated from your model.
Change the name of this class and the last return to the same name defined in the previous file.
class NewModelAlgorithm(QgsProcessingAlgorithm):

    def initAlgorithm(self, config=None):
    .
    .
    .

    def createInstance(self):
        return NewModelAlgorithm()

class Model2Algorithm(QgsProcessingAlgorithm):

    def initAlgorithm(self, config=None):
    .
    .
    .

    def createInstance(self):
        return Model2Algorithm()

5- Metadata.txt
In this file is the information that will be displayed on the plugin manager screen such as name, version, changelog.
In order for your plugin to appear in QGIS, move the full folder created by PuginBuilder to your user's python folder,
usually in C:\Users\User\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins.
In QGIS, go to Plugins > Manage and Install plugins and enable it in the Installed tab.
Your plugin should appear inside your toolbox.
Using IF.
If you need one model to be executed by another via an if structure in the _algorithm.py file, it will be inserted into processAlgorithm.
After the if, put the required code with one more tab.
class NewModelAlgorithm(QgsProcessingAlgorithm):

    def initAlgorithm(self, config=None):
    .
    .
    .

    def processAlgorithm(self, parameters, context, model_feedback):
        feedback = QgsProcessingMultiStepFeedback(55, model_feedback)
        results = {}
        outputs = {}
        if SOMETHING is None:
            PLACE YOUR CODE HERE
        elif OTHERSTUFF is not None:
            ANOTHER CODE HERE
        else:
            ONE MORE OPTION

All input and output parameters that will be used within the if must exist in the initAlgorithm section.
Comment: Hi **Herbert Santos**, How is the exported script from qgis model is linked to the plugin files(5), tried to follow the steps but failing to get output. Any clarification would be much appreciated
Comment: @MathewPetro when exporting a model to a script, copy the code generated starting in the class line, and paste it into the file 4 _algorithm.py creating new classes in the plugin. Did I clarify?
Comment: **Hello Herbert Santos**. Thank you a lot, it has worked, I have one extra question,  maybe it is not described here, iI would like to make this plugin to appear to the toolbar as well, I tried and end up with the only icon, and button in the toolbar but doesn't start when i click it from the toolbar kindly help me if you have any idea. Thanks
Comment: @MathewPetro As far as I understand plugins, it seems to me that they work differently when they are on the tollbar and on the tollbox. At the beginning of my answer it is written to define as a process provider. It is necessary to choose another option to work at the tollbar, but the step by step I mentioned here will not work in the same way. This is a method for plugins in which I have no knowledge yet.

Converting Model in Plug-in in QGIS