Difference between Augustinianism and Calvinism

Question: Is there a difference between Augustinianism and (Five Points) Calvinism as they relate to the doctrine of salvation?
If so, what is the difference?
Answer: Augustinianism is not nearly as specific as 5-points, Dordt Calvinism. For instance, I don't know of anyplace where Augustine specifically addresses limited atonement.
The largest difference is that Augustine held to single predestination (God chooses the elect, but does not actively reprobate anyone - he simply "passes over" them), while Calvin held to double predestination (God choose the elect to salvation, and the reprobate to damnation).
update
Here are some specific quotes of Augustine's, as they relate to some of the points of Calvinism:
Unconditional Election
On The Predestination of the Saints, ch. 11

Therefore the election obtained what it obtained gratuitously; there
  preceded none of those things which they might first give, and it
  should be given to them again. He saved them for nothing. But to the
  rest who were blinded, as is there plainly declared, it was done in
  recompense.

On The Predestination of the Saints, ch. 16

Faith, then, as well in its beginning as in its completion, is God's
  gift; and let no one have any doubt whatever, unless he desires to
  resist the plainest sacred writings, that this gift is given to some,
  while to some it is not given. But why it is not given to all ought
  not to disturb the believer, who believes that from one all have gone
  into a condemnation, which undoubtedly is most righteous; so that even
  if none were delivered therefrom, there would be no just cause for
  finding fault with God.

Irresistable Grace
Enchuridion ch. 25

Furthermore, who would be so impiously foolish as to say that God
  cannot turn the evil wills of men—as he willeth, when he willeth, and
  where he willeth—toward the good? But, when he acteth, he acteth
  through mercy; when he doth not act, it is through justice. For, "he
  hath mercy on whom he willeth; and whom he willeth, he hardeneth."

On The Predestination of the Saints, Ch. 13

This grace, therefore, which is hiddenly bestowed in human hearts by
  the Divine gift, is rejected by no hard heart, because it is given for
  the sake of first taking away the hardness of the heart.

Perseverence of the Saints
On The Predestination of the Saints, ch. 33

For all who are teachable of God come to the Son because they have
  heard and learned from the Father through the Son, who most clearly
  says, "Every one who has heard of the Father, and has learned, cometh
  unto me." But of such as these none perishes,
  because "of all that the Father hath given Him, He will lose
  none." Whoever, therefore, is of these does
  not perish at all; nor was any who perishes ever of these.

Single vs. Double Predestination
Look at the quotes under "unconditional election" above. Augustine speaks passively about the non-elect. God witholds the grace of election, but is not actively reprobating. Contrast this with Calvin on reprobation:
Institutes III.xxii.11:

At last, he concludes that God has mercy on whom he will have mercy,
  and whom he will he hardeneth (Rom. 9:18). You see how he refers both
  to the mere pleasure of God. Therefore, if we cannot assign any reason
  for his bestowing mercy on his people, but just that it so pleases
  him, neither can we have any reason for his reprobating others but his
  will.
Comment: An anonymous user thinks your conception of Augustine's predestination isn't right and I tend to agree with them.  Can you site the source (and maybe a source saying that this is the correct interpretation of Augustine)?
Comment: @SanJacinto By "active" I was just trying to speak about God's choices. For Calvin, God chooses to elect some and chooses to reject others - whether or not he has to "do" anything to reject the reprobate - and that choice is prior to any (lack of) merit on their part. I linked the Calvin quote, if you look at all of section 11 he is really clear about that. Augustine never spoke of reprobation in that way.
Comment: Yes, I can look some things up when I get home. What would you like clarity on? Do you just want evidence he believed in single-predestination and not double-predestination?
Comment: More like evidence that his conception of predestination had anything to do with Calvin's.  I've read what he says about predestination in City of God but I didn't understand it in light of Catholic teaching.  As a Doctor of the Church, I'm pretty sure his position informed Catholic doctrine and the way St. Paul's writings on predestination has been read by the Catholic Church and Calvin's main point was in opposition to Catholic teaching on predestination so I'm just wondering where the disconnect is.
Comment: You've set up a scenario whereby Calvin would defend an active reprobation as opposed to a passive one. Your quote of Calvin neither defends nor denies this claim. There is nothing in the quote that says Calvin believed that it requires God to actively _do_ something in order to harden and reprobate. The Calvinist authors I read believe that when God hardens, he actually does _nothing_ (in other words, he leaves them as they are in their default state of rejection), as opposed to working in the hearts of His chosen that they would repent. Can you find a better quote or else change your answer?
Comment: @gmoothart Thanks. I'll read the section when I have the time. My intuition is that you're not considering the default status of each individual from the fall. In this theology, each of us begins with a lack of merit and inherited guilt... ...unless I am wrong on Calvin's view of this, too. (I don't know... I haven't read him much).
Answer: 1,000 years before John Calvin was an idea. After His apologetic battle with Pelagius. Augustine wrote a book called On Grace and Free Will. This was necessitated by two extremes that he saw and had concluded (in agreement with all the fathers before him) that both extremes were in error and he would not be accused (as some were saying) that because of his arguments against Pelagius that he was denying the role of men's freedom of will. Augustine believed in neither a "total" depravity (as in absolute incapability) or in a post-Dordt Reformed position.
He writes in chapter 1

"*But since there are some persons who so defend God's grace as to deny man's free will, or who suppose that free will is denied when grace is defended, I have determined to write somewhat on this point to your Love, my brother Valenti*us, and the rest of you, who are serving God together under the impulse of a mutual love…*"

He goes on page after page defending the necessary requirement by God of man to respond to the word of truth, the gospel of our salvation. God speaks (whether through the word preached or read or heard through another) and God has sovereignly determined from before the foundation of the world that man must demonstrate belief (which is not a work according to Romans 4:2-5). He quotes form over 30 scriptures which in the Greek are in the imperative mood which precludes man can turn unto Him, receive, open the door when He knocks, etc.,
Opening chapter 2 he relates that

"Now He has revealed to us, through His Holy Scriptures, that there is in a man a free choice of will. But how He has revealed this I do not recount in human language, but in divine. There is, to begin with, the fact that God's precepts themselves would be of no use to a man unless he had free choice of will, so that by performing them he might obtain the promised rewards. For they are given that no one might be able to plead the excuse of ignorance, as the Lord says concerning the Jews in the gospel: If I had not come and spoken unto them, they would not have sin; but now they have no excuse for their sin…"

In chapter 4 he asks the logical question

"What is the import of the fact that in so many passages God requires all His commandments to be kept and fulfilled? How does He make this requisition, if there is no free will?"

And then answers it...he says ...

"...there are so many commandments which in some way are expressly adapted to the human will; for instance, there is, Be not overcome of evil, Romans 12:1 and others of similar import, such as, Be not like a horse or a mule, which have no understanding; and, Reject not the counsels of your mother; Proverbs 1:8 and, Be not wise in your own conceit; Proverbs 3:7 and, Despise not the chastening of the Lord; Proverbs 3:11 and, Forget not my law; Proverbs 3:1 and, Forbear not to do good to the poor; Proverbs 3:27 and, Devise not evil against your friend; Proverbs 3:29 and, Give no heed to a worthless woman; Proverbs 5:2 and, He is not inclined to understand how to do good; and, They refused to attend to my counsel; Proverbs 1:30 with numberless other passages of the inspired Scriptures of the Old Testament. And what do they all show us but the free choice of the human will? So, again, in the evangelical and apostolic books of the New Testament what other lesson is taught us? As when it is said, Lay not up for yourselves treasures upon earth; Matthew 6:19 and, Fear not them which kill the body; Matthew 10:28 and, If any man will come after me, let him deny himself; Matthew 16:24 and again, Peace on earth to men of good will. Luke 2:14 So also that the Apostle Paul says: Let him do what he wills; he sins not if he marry. Nevertheless, he that stands steadfast in his heart, having no necessity, but has power over his own will, and has so decreed in his heart that he will keep his virgin, does well. 1 Corinthians 7:36-37 And so again, If I do this willingly, I have a reward; 1 Corinthians 9:17 while in another passage he says, Be sober and righteous, and sin not; 1 Corinthians 15:34 and again, As you have a readiness to will, so also let there be a prompt performance; 2 Corinthians 8:11 then he remarks to Timothy about the younger widows, When they have begun to wax wanton against Christ, they choose to marry. So in another passage, All that will to live godly in Christ Jesus shall suffer persecution; 2 Timothy 3:12 while to Timothy himself he says, Neglect not the gift that is in you. 1 Timothy 4:14 Then to Philemon he addresses this explanation: That your benefit should not be as it were of necessity, but of your own will. Servants also he advises to obey their masters with a good will. Ephesians 6:7 In strict accordance with this, James says: Do not err, my beloved brethren . . . and have not the faith of our Lord Jesus Christ with respect to persons; and, Do not speak evil one of another. James 4:11 So also John in his Epistle writes, Do not love the world, 1 John 2:15and other things of the same import. Now wherever it is said, Do not do this, and Do not do that, and wherever there is any requirement in the divine admonitions for the work of the will to do anything, or to refrain from doing anything, there is at once a sufficient proof of free will. No man, therefore, when he sins, can in his heart blame God for it, but every man must impute the fault to himself. Nor does it detract at all from a man's own will when he performs any act in accordance with God. Indeed, a work is then to be pronounced a good one when a person does it willingly; then, too, may the reward of a good work be hoped for from Him concerning whom it is written, He shall reward every man according to his works. Matthew 16:27"

This is the exact opinion (the mutual existence of predestination and free will and NOT TOTAL depravity) that one will find going all the way back to Justin. All the fathers in whatever church, in whatever nation, regardless of which Apostle founded the church and taught and appointed these earliest teachers, all taught the self same one unified doctrine. After Calvin a theological war began that has lasted 500 years (you shall know then by their fruit)...Calvin is precisely the extreme error Augustine here refutes.
Comment: Welcome to the site.  This is a really good answer.  As a new visitor, I'd recommend checking out the following two posts, which are meant to help newcomers "learn the ropes": [help page](http://christianity.stackexchange.com/help) and [How we are different than other sites?](http://meta.christianity.stackexchange.com/questions/1808/how-we-are-different-than-other-sites)
Comment: Very nice first answer!
Answer: Five Point Calvinism teaches is based on five key points:

Total Depravity
Every member of the human race is corrupt in heart, mind, and soul.

Unconditional election
God has chosen (solely of his own will) some for glory and some for damnation.

Limited atonement
Christ died only to forgive the sins of those who are called by his name.

Irresistible grace
The saving grace of God is applied to those who he has determined to save.

Perseverance of the saints
Those who are truly saved will persevere and will not lose their salvation.

Calvinism in regards to salvation is rooted in Augustinianism to the point where it's often called Augustinianism.
While Augustinianism did not have five distinct points (as outlined above), it did agree with (and was the source of) each of these.
Comment: Calvinism as I understand it see the five points as an inherently coherent system, where each point is logically dependent on the 4 others. Is there such an idea of a unified system of soteriology in Augustinianism?
Comment: That's a fascinating question!  Having studied this topic for a full hour now, I'm sure I'm the expert.  :P j/k.  Seriously, though... From what I've seen, there does seem to be a common thread or theory that unites these concepts, but I don't think that Augustine went so far as to say that they are all reliant on each other.  However, all the concepts together seem to be unified in a way that can't be separated--a belief in any one seems to lead to a belief in the rest.  But I haven't seen anything specific stating that from Augustine.
Answer: Calvinism is merely a political ideology dressed up as theology that uses Augustine as cover.
The Five Points (and more generally the Five Solae) are a byproduct of Calvin's effort to circumvent the role of the Papacy in validating the divine right of kings.
A king who enjoys a divine right is absolutely sovereign. His sovereignty does not require the assent of his subjects (nor even their existence, for that matter). But his subjects, to be subjects, do require the the king's acknowledgement, at the very least.
This was a one-way relationship that flowed from the Papacy to the royalty and then to the citizenry. Calvin merely sought to remove the Papacy and royalty from this political hierarchy. Doing so required establishing the Divine as being the only absolute sovereign who could exercise acknowledgement of "subjects." And He does so by either extending grace or withholding it. The subjects themselves, on the other hand, aren't even necessary for God to be what He is. After all, He is absolutely sovereign.
The Five Points then became, in the earthly realm, the necessary suppositions of Calvin's design, otherwise the entire theological schema would be incoherent.
This envelops too many ironies and self-contradictions to enumerate here. But just to whet the appetite.
1) When Calvinism established that humans belong to one of two categories: the unconditionally elected and reprobates -- he might have as well labeled them "angels" and "brute animals."
2) Calvin wasn't very bright. Most "thinkers" who appropriate the ideas of others usually aren't. One of the prime examples that his thinking was pedestrian is that his whole theological schema assumes a pre-critical (if not antiquated) understanding of time. And to compound his mistake, he conflated temporality with eternity. If I explained any further, I'd need the space of the a dissertation. But it makes one wonder if he simply glossed over Augustine on that account.
3) I'm sometimes asked, if those who are saved are "unconditionally elected," what is their impetus to do good? After all, sola fide, no? Reformed adherents will tell you, the obvious reason is that those who are saved can do nothing but good. But the real answer simply is: they do good, not because they are unconditionally elected, but because they need to prove to themselves and their neighbor they are unconditionally elected. What's doubly ironic, is that such a motive is an absolute rejection of Augustine's teaching on Christ's Two Fold Rule of Charity.
[I will take any and all "down votes" as a sign that it is hopefully someone who might one day begin to think critically about how morally bankrupt Reformed Theology actually is. I care far more about your salvation than being right about Calvin's politically nefarious formulation of the nature of salvation.]
Answer: I appreciate "gmoothart" addressing your question of where they differ, while I, biblical scholars, historical scholars, and laymen who care about the truth should be mortified by "Brother Paul"'s & "Jamie Andrew"'s responses.
To answer the original question:
Augustine taught on the free will of man, if memory serves, as a response to the Manichean lack of free will ideology 1. As many modern Pelagians will point out, Augustine "changed his mind" later in life when refuting Pelagian and his followers. This was truly an adjustment of focusing so heavily on the freedom of the will against those who didn't think it existed to focusing on the sinful nature of man when Pelagians took the freedom of the will to the opposite heretical extreme.
Calvin never taught five points. Whether in his first rendition of his institutes at the age of 26 (~three years after becoming a Christian) 2, or by the final working before his death, he saw the fullness of Scripture being interconnected, systematic, from cover to cover (as if God is one God speaking with one unified voice). The common notion that Calvin led the charge on 'predestination' (Paul's words 1500 years before) is false given Luther wrote Bondage of the Will in 1525 3 after having written and preached on most of the Bible for a decade & when Calvin was 16 (10 years before the first of the Institutes). One can read that Luther wrote more, and more zealously, on the bondage of the will, borrowing from Augustine, than Calvin ever did. The 'Five Points' are a misnomer attributed to Calvin because the Canons of Dort published their response to Arminius' disciple's 'Five Point' Remonstrance in 1610 (46 years after Calvin died). The response was actually formatted as "U.L.T/I.P." or in four points but is referenced in five because of the formatting of The Remonstrance 4. 'Calvinists' likewise is a misnomer to limit the scope of a person's theology away from the fullness and interconnectedness of Biblical theology (Reformed) to a soteriological hyper-fixation (typically to Strawman as a philosophical Fatalist).
Difference: Depends on when you stop reading. Augustine, Luther, Calvin, your local preacher; everyone has some theological point in error and cannot see the fallacy they are committing (typically because it hasn't been pointed out or because they don't like the idea that reversing 1 theological point means other connected internal viewpoints would necessarily have to change, thus admitting to themselves or others they have been wrong). On the topic of soteriology: they - Reformed theologians such as Luther and Calvin - and Augustine, who they captured insight from and saw historical footing in, are on the same page.
As to the notions of Brother Paul that Augustine 'did not believe man had original sin [in its relation to the gospel as a whole: through the sin of Adam man fell (Romans 5:19), thus is unable to choose salvation apart from God's grace alone (Romans 3:9-18)(original sin); but through the propitiation of the sacrificial blood of His only begotten Son, Jesus the Christ (1 John 4:10; Romans 3:24-26), we are adopted as sons and heirs (Romans 8:16-17)]' this is in direct contradiction to Augustine's writings:

The Manicheans rebuke the concupiscence of the flesh, not as if it were an accidental vice, but as if it were a nature bad from eternity; the Pelagians approve it as if it were no vice, but even a natural good. The catholic faith condemns both, saying to the Manicheans, It is not nature, but it is vice; saying to the Pelagians, It is not of the Father, but it is of the world; in order that both may allow it as an evil sickness to be cured — the former by ceasing to believe it, as it were, incurable, the latter by ceasing to proclaim it as laudable. The Manicheans deny that to a good man the beginning of evil came from free will; the Pelagians say that even a bad man has free will sufficiently to perform the good commandment. The catholic Church condemns both, saying to the former, God made man upright, Ecclesiastes 7:30 and saying to the latter, If the Son shall make you free, you shall be free indeed. John 8:36 The Manicheans say that the soul, as a particle of God, has sin by the commixture of an evil nature; the Pelagians say that the soul is upright, not indeed a particle, but a creature of God, and has not even in this corruptible life any sin. The catholic Church condemns both, saying to the Manicheans, Either make the tree good and its fruit good, or make the tree evil and its fruit evil, Matthew 12:33 which would not be said to man who cannot make his own nature, unless because sin is not nature, but vice; and saying to the Pelagians, If we say that we have no sin we deceive ourselves, and the truth is not in us. 1 John 1:8" 5

Much more can be read by Augustine's own hand as he summarizes his arguments against the Pelagians and their plague on the church as he writes to Bonafice. Luther - and as a consequence Calvin - is confirmed by Augustine.
To Jamie Andrews:
The venomous straw-manning and ad hominin fallacies presented are not helpful and outright horrendous to spout to a young believer who is asking a fundamental question. Clearly, the warning Jesus gives in Matt18:6 about misleading children escapes you. 'Calvinism' - starting nearly 50 years after his death while Reformed theology started a decade after Calvin was born - cannot be a political movement. Both Luther and Calvin wrote against the rebellion of people "A Sincere... Against Insurrection and Rebellion" - Luther 1522[3]. It's no illusion that people who differ from ad hominin assaults do so because they don't have logical arguments to stand by, but given this level of venom, I'd like to ask the moderators to remove his post.
Calvin wasn't very bright? The next "as bright/brighter" young geniuses included Pascal (+100) & Motzart (+200), and if you include those credited as geniuses later in their lives: Newton & Leibniz 100 years later, Edwards and Tesla 200 years later, and so on into relatively modern times (Einstein, Feynman, etc). That's an incredibly small list of geniuses (abbreviated obviously to prove a point). Biblical seminaries still teach out of his institutes (for strengths and few errors) 500 years later compared to pillars of thought like Plato or Aristotle which if taught the full corpus of their works would be showing well over 50% errors (and did they restructure all of philosophy in a mere three years of being introduced to it?). Agree or disagree with his work, his genius is unquestioned.
1 NPNF1-04. Augustine: The Writings Against the Manichaeans and Against the Donatists
2 The Development and Impact of John Calvin's 'Institutes of the Christian Religion'
3 A Chronological List of Luther's Works from the American Edition
4 The Canons of Dort
5 Against Two Letters of the Pelagians (Book II)


MAAS networking

Question: I installed MAAS and autopilot installed Openstack. I have VM instances running and reachable. My question is i would like to add additional VLAN's now to put VM instances in different networks. I noticed that in MAAS setup for a node network setup VLAN is untagged always and i am not able to change this setting?
Answer: To answer my own question it might help someone else... In the meantime updated the os on the MAAS to 16.04 which in turn updated MAAS components and bumped MAAS to 2.0.
Under networking tab i added all the VLANS i had. Then updated each interface under nodes with the correct VLAN data. Tried to run sudo openstack-install again. It fails. Google and found out no more openstack-install in 16.04. Now you need to use conjure-up openstack. This fails miserably not matter the options i try :(. Also no autopilot when you use conjure-up :(.

MAAS networking


Event Report filter not working

Question: I am trying to create an event report but I am not able to filter a specific event in the Event filter, it shows as "None found" even when there are active events present and there is no error in the browser console. Kindly help me to fix the issue.
Comment: What CMS are you using? Also, have you checked the error logs, You can sometimes find useful debugging information that can help :-)
Comment: @Ember I am using Drupal 7 and I didn't find logs related to this.
Answer: It can be a good idea to clear all CiviCRM caches. You can do that using the url https://www.yourdomain.com/civicrm/menu/rebuild.
Regarding the logs, you can turn on logging and debugging in CiviCRM (https://www.yourdomain.com/civicrm/admin/setting/debug?reset=1) and then have a look at the log available in Drupal's UI first: https://www.yourdomain.com/admin/reports/dblog

Event Report filter not working


Why do we read about forbidden relationships on Yom Kippur

Question: Part of the torah reading on Yom Kippur is the list of forbidden intimate relationships in Vayikra 18. I would like to know why we read that section of the torah on Yom Kippur
Comment: related http://judaism.stackexchange.com/q/76815/759
Answer: In the Shulchan Aruch, O"C, 622:2, the Taz explains (my loose translation) that [sub 4] Tosafot explain that the connection is that in the same waay that we are enjoined from uncovering nakedness, Hashem will not uncover our sins, then he mentions that since man is most drawn to these sins, we need extra reminders on the day which is most awesome and most engraved in our hearts. These are also mentioned in the Be'eir Heitev who cites Talmud Megilla 31a and the Tosafot there which says that the reminder is needed because the women are adorned for the Kavod of the day so they must be cautioned that no one should stumble on their account in these areas.
Comment: http://mechon-mamre.org/i/2213.htm#11
Comment: לְפִי שֶׁהָעֲרָיוֹת עֲבֵרָה מְצוּיָה, שֶׁנַּפְשׁוֹ שֶׁל אָדָם מְחַמְּדָתָן וְיִצְרוֹ תּוֹקְפוֹ. רַשִׁ"י. וּכְלוֹמַר וְכָל מִי שֶׁנִּכְשַׁל בְּאַחַת מֵהֶן יִזְכֹּר וְיִכָּלֵם וְיַחְזֹר בִּתְשׁוּבָה. הָרַמְבַּ"ם:  yikar To YT


Can prism separate different colour of light?

Question: Can prism separate colours of light?
For example, I have a purple colour. purple colour is by mixing of red and blue.
I that possible when purple colour light is passed through a prism it separate the red and blue colours.
Why it cannot split purple into red and blue?
Comment: But also note: "Purple" is special because you can only get purple by mixing red and blue. On the opposite side of the color wheel you've got yellow. If you see a light source that looks yellow, it either could be a mix of red and green, or it could be a single, pure wavelength. The prism will split red from green, but it will _not_ split the single, pure wavelength into red and green.
Comment: Yes, definitely! Isaac Newton is rather famous for doing such things!
Comment: @SolomonSlow Indeed! I even have an old bipolar LED that emitted red light when powered with one electrical polarity and it emitted green light when powered with the opposite polarity. So yellow was just a matter of using appropriate alternating polarity power for the LED.
Comment: red blue and green are not the only fundamental frequencies of colour, you would not decompose a purple into its components colours since it is assumed we have one frequency of light incident the prism, purple.
Comment: If you make purple light by adding together red and blue light, then a prism can separate them. If you think purple has an assigned wavelength, or is a very narrow spectral band around some assigned wavelength, then a prism will do little or nothing. Personally, I think purple is a mixture of colors, so a prism will disperse the constituent colors. This is a very easy experiment to do.
Answer: Getting new colors by mixing different colors of light is a trick played on your brain by your retina, called metamerism. If you put a prism in the path of a beam of light that is mixture of two colors that appear to be a third color to your eye, the prism will separate them into the two original colors. If you put a prism in the path of a beam which consists of pure purple (produced, say, by another prism or a monochromatic source), it will not split that beam into more and different colors. You'll still get just purple.
Comment: @EdV, 380 nanometers. -NN
Comment: There's a whole line of purples. https://en.wikipedia.org/wiki/Line_of_purples Unfortunately, they lie entirely outside the sRGB gamut, so they can't be correctly represented on most monitors, or stored in typical image file formats.
Comment: Pure purple? What wavelength would that be?
Comment: @edv, Yowza! it would be cool if you could post the spectra here for us to look at! -NN
Answer: It appears that there are two schools of thought in the matter of the color purple. One school, of which I am a member, holds that purple is a mixture of red and either blue or violet. It is not a color with a canonically or customarily assigned wavelength. It is not a narrow continuous spectral range of wavelengths. The other school considers purple to be a color, either pure or of narrow spectral width.
So the answer to the OP's question depends on which school aligns with their notion or perception of purple.
To illustrate my view, consider the light produced by an old GE Glow lamp. These were formerly used as inexpensively operated night lights. They produced what I see as purple light:

But my visual perception of purple light from this lamp tells me nothing at all about the light's relevant spectral properties. However, I have two homemade echelle spectrographs, so I can collect light from the lamp, using a lens and fiber optic collimator:

The other end of the 50 micron fiber optic cable is connected to one of my echelle spectrographs. This allows me to obtain a spectrum, called an echellogram, of the light from the lamp.
This next photograph is the resulting echellogram of the lamp's light. It is a 30s exposure at ISO 6400.

A longer exposure, of 121s, produces this echellogram:

Both of these echellograms show that red and violet spectral lines are prominent and green spectral lines are relatively less prominent. This is consistent with me seeing the light as purple.

Content below is not an actual answer: it just attempts to add some possibly helpful information.
To begin, light from various light sources, such as LEDs, tungsten filament light bulbs, sunlight, hollow cathode lamps, etc., typically consists of spectral ranges of constituent 'colors'. For LEDs, the spectral ranges are continuums, whereas for hollow cathode lamps (the typical atomic absorption spectroscopy light sources), the spectral output consists of many narrow spectral lines.
Using the echelle spectrograph shown here, it is easy to spectrally disperse the light from a desired light source. The spectra, called echellograms, are two dimensional, unlike the typically one dimensional spectra produced by single gratings or prisms. The echellograms are somewhat quirky in that the grating orders, which look like curved arcs, can have some redundancy.
Using various colored LEDs I happen to have in my junk drawer, here are their echellograms:

The UV LED has a nominal center wavelength of 395 nm and a measured center wavelength of 398 nm.

In contrast, here are echellograms for a strontium hollow cathode lamp with neon fill gas:

and an iron hollow cathode lamp with neon fill gas:

For both of the hollow cathode lamp echellograms, a blue filter was used to attenuate the intense red region neon spectral lines.
Comment: Pretty! And I expect they look even better live. :) Modern colour displays are pretty good, but their gamuts are still noticeably smaller than what humans (without colour-blindness) can typically see.
Comment: @PM2Ring They do, indeed, look better live! In fact, I built the second spectrograph, in a shoe box sized salvaged metal box, specifically so I could position an eye as close to the cross dispersion prism as possible. The field of view then is stunning: the echelle grating arcs extend roughly 150 degrees.
Answer: According to the question, can prism split it separate different colours.
Due to the conic nature of our retina, we process an extremely large amalgamation of light reflections, the ratio of which is to be seen as a perfect spectral color. So, in reality, you are seeing violet; red and blue with a little more blue, whereas when you see purple, it's more of a red and blue 1:1 situation
As prism has not such biology in it.hence it will split purple colour light into red and blue colour light
And only VIBGYOR has a wavelength in all colours.If any colour of light is passed through than only from these colours we will get through prism.
Comment: As it's currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer).


Prove EXP to be regular or non-regular

Question: Given L is regular, Prove/Disprove that the following language is regular or not.
$EXP = \{w| w^{|w|} ∈L\}$
Comment: What do you think? What have you tried, and where did you get stuck?
Comment: Welcome to Computer Science! We discourage posts that simply state a problem out of context, and expect the community to solve it. Assuming you tried to solve it yourself and got stuck, it may be helpful if you wrote your thoughts and what you could not figure out. It will definitely draw more answers to your post. Until then, the question will be voted to be closed / downvoted. You may also want to check out [these hints](http://meta.cs.stackexchange.com/q/1284/98), or use the search engine of this site to find similar questions that were already answered.
Comment: Oh, I did to try to find and used others to solve this. I'm sorry I should've mentioned my thoughts. Thanks!
Answer: Suppose that $L$ is accepted by a DFA with states $Q$, initial state $q_0$, accepting states $F$, and transition function $\delta$.
With every word $w$ we can associate the function $\delta_w\colon Q \to Q$ given by $\delta_w(q) = \delta(q,w)$. Note that there are finitely many such function. It is not hard to check that for any such function $\delta_w$, the language $L_{\delta_w} = \{ x : \delta_x = \delta_w \}$ is regular.
We can also associate with $w$ a set $N_w = \{ n \in \mathbb{N} : \delta(q_0,w^n) \in F \}$. Note that $N_w$ depends only on $\delta_w$, and so there are finitely many such sets. Moreover, each of them is eventually periodic (why?), and so the language $L_{N_w} = \{ x : |x| \in N_w \}$ is regular.
Combining the two observations, we see that
$$
EXP = \bigcup_{w \in \Sigma^*} (L_{\delta_w} \cap L_{N_w}).
$$
While the sum is infinite, there are only finitely many different summands, and we deduce that $EXP$ is regular.

Prove EXP to be regular or non-regular


Check writing software for Linux Mint 17

Question: I'm trying to switch from Windows. I have check writing software (Avanquest Softcheck) for Windows; unfortunately they don't support Linux. Looked into gnucash and moneydance, but they only print preprinted checks. I need software that will print everything onto a completely blank check stock including micr numbers. Tried to use virtual software but I guess I'm not proficient enough to get them working. I don't want to go back to Windows (this the only issue that is keeping me from going 100% Linux). Please let me know if there is any other software or packages out there I could use or if someone can come with something.
Comment: TIL people still use checks
Answer: Try to install it under wine, software from similar line of products have gold status of testing, this is old test results but it can be useful:
https://appdb.winehq.org/objectManager.php?sClass=version&iId=23096
Check information and tutorials about wine at wine wiki http://wiki.winehq.org/
Check Kraft also


Is every subgroup of automorphisms a Galois group?

Question:
Let $G=\{\sigma_1=1, \sigma_2, \dots,\sigma_n\}$ be a subgroup of automorphisms of a field $K$ and let $F$ be the fixed field. Then $[K:F]=|G|$

Why is this always true? I thought this would be true only if $K$ was the Galois extension of $F$ and $G$ was $\text{Aut}(K/F)$
Comment: Did you understand this statement properly? Actually I have the same question to ask. :(
Answer: Let $E$ be a field, $G$ be a finite subgroup of $\textrm{Aut}(E)$ and $F:=\textrm{Fix}(G)$. The result you are trying to prove is usually called fixed subfield formula and relies on the Artin's lemma, that is:

Lemma 1. $[E:F]\leqslant |G|$.

Proof. A proof can be found in the Jacobson's Basic Algebra I:
 $\Box$
To establish the fixed subfield formula, one has now to show that:

Lemma 2. $[E:F]\geqslant|G|$.

Proof. Let $m:=\left[E:F\right]$, $n:=|G|$ and assume by contradiction that $m<n$. Let $(x_i)_{i\in\{1,\ldots,m\}}\in E^m$ be a $F$-basis of $E$ and $\sigma_1,\ldots,\sigma_n$ be the distinct elements of $G$. Since $m<n$ there exists $(y_i)_{i\in\{1,\ldots,n\}}\in E^n$ a nonzero solution to the following homogeneous system: $$\forall i\in\{1,\ldots,m\},\sum_{i=1}^n\sigma_j(x_i)Y_i=0_E.$$
Let $x\in E$, there exists $(\lambda_i)_{i\in\{1,\ldots,m\}}\in(E^G)^m$ such that: $$x=\sum_{i=1}^m\lambda_ix_i.$$
One derives from the construction of $(y_i)_{i\in\{1,\ldots,n\}}$: $$\sum_{i=1}^n\sigma(x)y_i=\sum_{i=1}^m\lambda_i\sum_{j=1}^n\sigma_i(x_j)y_i=0_L.$$
Therefore, one has: $$\sum_{i=1}^n\sigma y_i=0_{\textrm{Map}(G,E)}.$$
Since $(y_i)_{i\in\{1,\ldots,n\}}$ is nonzero and $\sigma_1,\ldots,\sigma_n$ are pairwise distinct, here is a contradiction to Dedekind's lemma (see Lemma $1.1.$ at p$.1$). $\Box$


Can a court retroactively annul a vow that was already annulled by the father/husband?

Question: If a woman made a vow and violated it, and it was later annulled by her father/husband, can the court now annul the vow retroactively if it finds an opening, thereby exempting her from being liable?
Comment: Here's a gemara that says what you said (but not for avadim): https://www.sefaria.org/Nazir.62b.1?lang=bi&with=all&lang2=en
Answer: It seems from the plain language of the Rambam in Haflaah, Nedarim, 12:19 that she would be liable regardless, and that a court can not help her here. The commentaries seem silent regarding this question too, suggesting the same.
However, see the commentary from חיל המלך on Haflaah, Shvuos, 6:18. It's not a super tough read, so I suggest checking it out yourself, but I'll write out my cursory read just in case it helps:
The Rambam over there sets the precedent that in a case where one violated a shvuas bitui (promise dictating behavior in the future) and then asked for release from the vow from a court, that would be effective retroactively. The חיל המלך brings out two relevant points to this question. First, the Rambam believes that even in a case where the original vow can no longer incur a penalty, such as if someone promised not to eat a specific loaf of bread, ate the whole thing, and then asked for release from a court, that release is effective. That seems a lot like our case, where the woman can no longer incur a penalty anyways because of her husband's cancellation.
The second point he makes is that this appears to only apply if the judgement would actually be carried out. Therefore, nowadays, since penalties of lashes and sacrifices would not actually be applied, this is not effective. He ends off by saying that we should do more research on the opinion of the Rambam on this final matter.
If you want to do more research, I'd check out the gemarah he quotes, then look for נר משפט on that page. If that doesn't make it into Shulchan Aruch because it discusses sacrifices, Likkutei Halachos from the Chofetz Chaim probably does rule on it.


Is it possible to be an expert in a skill at level 2?

Question: In the first public draft of the Pathfinder 2e playtest (Aug. 2018), there are several second level feats that require expert in various skills. One example is Magical Crafting. It seems as if it is not possible to have an expert rank in a skill until level 3 when you get your first skill increase. Is it possible for any character to choose one of these skill feats at level 2?
Comment: Should this question be updated to be about Pathfinder 2e print?
Comment: @Ifusaso no because the question *is about* the playtest material, not the official released material. Changing the question might invalidate the current accepted answer (whether the answer is the same for the playtest and the official rules, I don't know) and wouldn't preserve the original meaning of the question.
Answer: Yes, it's possible
There are ways to become Expert in a skill as early as 2nd level, such as the Gnome racial feat Obsessive:

Pick a category of the Lore skill. You are trained in that skill. At 2nd level you become an expert

Rogues also gain a skill increase at 2nd level, and another skill increase every level, instead of every 2 levels like the other classes (starting at 3rd):

At 2nd level and every level thereafter, you gain a skill increase. You can use this increase to either become trained in one skill you're untrained in, or become an expert in one skill in which you're already trained.

So, it seems like all those Acrobatics and Athletics themed feats available at 2nd level are just at the right level for rogues to get them. Magical Crafting, as weird as it sounds, is also possible for a 2nd level rogue. While other classes would have to wait to take it at 3rd level or later.
Answer: Also, if you take certain dedications, you get to go expert in something if you're already trained.  As of today, they're in Lost Omens: World Guide and Advanced Players Guide.
A few examples:

Pathfinder Agent dedication-go expert in anything you're already trained in
Aldori Duelist-Acrobatics or Athletics & Dueling Lore
Lastwall Sentry-Athletics & Undead Lore
Lion Blade-Deception or Stealth & Espionage Lore
Acrobat-Acrobatics
Marshal-Diplomacy or Intimidation
Comment: This seems to be an answer about current Pathfinder 2e content; but the question was about the Playtest. I'm not sure if this is an invalid answer or if the question should be updated to be about the actual print 2e.


Can The Chief Justice Excuse Senators From The Jury In A Presidential Impeachment?

Question: In a normal trial the judge presides over jury selection during the voir dire process. Jurors are excused for causes such as lack of impartiality. Does the Chief Justice of the US Supreme Court have the authority to excuse senators from a presidential impeachment if the Chief Justice determines them to be partial to one side or the other?
Comment: If senators were excused on the grounds of lack of impartiality I expect the Chief justice would sit in front of an empty senate.
Comment: The Chief Justice is not presiding in the 2021 impeachment proceeding, of course.
Comment: The senate is rather more analogous to a panel of judges than to a jury.
Answer:
Can The Chief Justice Excuse Senators From The Jury In A Presidential Impeachment?

No, the jury (such as it may be) is fixed by the Constitution. Article I, Section 3, "The Senate shall have the sole Power to try all Impeachments." Trials of impeachment may include judges and other civil officers, Article 2, Section 4, where the chief justice would not be the presiding officer.
There is nothing in the Senate rules permitting the presiding officer to excuse any Senator. However, a Senator may be excused, by stating a reason, and by vote of a majority of Senators present.1
There are numerous examples in the Procedure and Guidelines for Impeachment Trials ..., including,

In the trial of Judge Charles Swayne in 1905, just before the vote was to be taken on the first article of impeachment, Senator P. C. Knox of Pennsylvania asked to be excused from voting as a result of his absence on account of illness. The Presiding Officer put the question and the Senator was excused.

A total of twenty-one requests by Senators to be excused from voting were granted during votes on the articles involving Judge Louderback.

1 PROCEDURE AND GUIDELINES FOR IMPEACHMENT TRIALS IN THE UNITED STATES SENATE, Excused from Participation in Trial or from Voting, pp. 77-78.
Comment: Re; "a Senator may request to be excused". Note the additional wording of Article I, section 3:  "When sitting for that Purpose, they shall be on Oath or Affirmation." along with "And no Person shall be convicted without the Concurrence of two thirds of the Members present."  A Senator appears to have the Constitutional power to "self-excuse" by refusing to take the "Oath or Affirmation" or by simply not being "present". Article I, Section 5: "may be authorized to compel the Attendance of absent Members, in such Manner, and under such Penalties as each House may provide." may apply, though.
Answer: No, the presiding Chief Justice only has the responsibility of enforcing the rules of order (time limits for each side to speak, reading the results of the final impeachment vote, etc.) The Justice in this case is a referee and not allowed any say in the activities of Senate or in whether there is a conviction or not. Senators may choose to excuse themselves and the Constitution allows for the conviction to occur when 2/3rds of the senators PRESENT vote to convict.


How can I split a large text file into chunks of 500 words or so?

Question: I know there's the command split which can split a file into several chunks based on file size, and then there's the command wc which can count words. I just don't know how to use the two together.
Comment: if you need to do this on a regular basis, i would just recommend thinking in terms of lines or number of chunks. if it absolutely must be about number of words, the `csplit` command is what you are looking for, in my opinion.
Comment: This is for a word frequency analysis, so it's important that the files are split by words.
Answer: Must it be done with wc? Because here I've ran into a very nice attempt to use regex as a csplit pattern. I don't have a system to test it right now but the regex itself seem to do the job.
The expression looks like that:
 csplit input-file.txt '/([\w.,;]+\s+){500}/'

Comment: With quotes I get: `csplit: '/([\\w.,;]+\\s+){500}/': match not found`
Comment: nice, but it's not working: `bash: syntax error near unexpected token `('`
Comment: @ixtmixilix You have to quote the argument for the shell.
Answer: Try doing this :
file=/etc/passwd
count=2
count_file_lines=$(wc -l < "$file")
split -n$((count_file_lines/count)) "$file"
ls -ltr x*

That will divide a file by $count (2)
Comment: The Op wants to split by words, not lines. Also, why are you using a variable for count if it does not change?
Answer: See if this helps (I would try it in a temporary directory first):
perl -e '
         undef $/;
         $file=<>;
         while($file=~ /\G((\S+\s+){500})/gc)
         {
            $i++;
            open A,">","chunk-$i.txt";
            print A $1;
            close A;
         }
         $i++;
         if($file=~ /\G(.+)\Z/sg)
         {
          open A,">","chunk-$i.txt";
          print A $1;
         }
        '  your_file_name_here

Edit: Code corrected and tested. Sorry for the previous mistakes.
Edit 2: This will spit out files called chunk-#.txt starting from chunk-1.txt. Each "chunk" will contain 500 words and the last "chunk" will contain whatever is left in the file (<=500 words). You can customize this behavior by changing the relevant parts in the code.
Answer: Unix utilities usually operate on full lines, so your best bet is to first modify your input so that it writes one word per line, like this (you might have to modify this command a bit if you have other characters in your words):
<inputfile tr -c A-Za-z0-9 \\n

Since you're only interested in the words, it might be a good idea to get rid of the blank lines, by piping the output into a grep call. Here's how your full command might look like:
<inputfile tr -c A-Za-z0-9 \\n | grep -v '^$' | split -l 500

You could later join the new files in order to get everything back on a single line (using something like tr -d \\n), but if you're planning on doing more manipulation with Unix tools, keep them this way, split is not the only program that will operate on whole lines.
Comment: This is interesting, but completely butchers the content of the text (in this case, a novel). Ideally, I'd like to preserve the line breaks where they are.
Comment: Yes I thought about preserving the line breaks, and I can think of a few hacks to retrieve them after processing, (like initially replacing them with a unique character and translating that unique character back to a newline at the end) but I'm afraid I don't know the proper technique to do this in a robust way that guarantees a 100% success. I wish someone with more experience could chime in to solve this problem.
Answer: You can also use this software for split word files. Word Files Splitter is an excellent tool to split a single word file into multiple word files according to number of pages or number of sections in a word files.
http://www.windowindia.net/word-files-splitter.html
Answer: This simple command line should do the trick. It will create multiple chunks of 70 characters from the source text file

cntr=1;for chunk in `sed -e 's/.\{70\}/&\n/g' source.txt`; do echo $chunk > chunk$cntr.txt; cntr=$(( $cntr + 1 )); done
Comment: But this splits the text along characters, right? I'm looking for a solution that keeps words intact.
Comment: ah of course. I totally misunderstood.


Calculating in SQL the first working day of a given month

Question: I have to calculate all the invoices which have been paid in the first 'N' days of a month. I have two tables
. INVOICE: it has the invoice information. The only field which does matter is called 'datePayment'
. HOLYDAYS: It is a one column table. Entries at this table are of the form "2009-01-01",
  2009-05-01" and so on.
I should consider also Saturdays and Sundays
(this might be not a problem because I could insert those days at the Hollidays table in order to consider them as hollidays if neccesary)
The problem is to calculate which is the 'payment limit'.
select count(*) from invoice
where datePayment  < PAYMENTLIMIT

My question is how to calculate this PAYMENTLIMIT. Where PAYMENTLIMIT is 'the fifth working day of every month'.
The query should be run under Mysql and Oracle therefore standard SQL should be used.
Any hint?
EDIT
In order to be consistent with the title of the question the pseudo-query should the read as follows:
select count(*) from invoice
where datePayment  < FIRST_WORKING_DAY + N

then the question can be reduced to calculate the FIRST_WORKING_DAY of every month.
Comment: The correct spelling of your 2nd table is "holiday"
Comment: In fact the table is called 'Feiertag'. :-) Anyway, thanks for the comment.  will correct it.
Comment: I am having trouble understanding what your question is.  Do you want to know how to find the first working day for each month or what the payment limit is?  Is payment limit the first working day + 5 more working days?
Answer: You could look for the first date in a month, where the date is not in the holiday table and the date is not a weekend:
select min(datePayment), datepart(mm, datePayment)
from invoices
where datepart(dw, datePayment) not in (1,7) --day of week
and not exists (select holiday from holidays where holiday = datePayment)
group by datepart(mm, datePayment) --monthnr

Comment: or the other way round...pre-calculate all first working days in a month and store them in a table. so you only have to query this table
Answer: Something like this might work:
create function dbo.GetFirstWorkdayOfMonth(@Year INT, @Month INT)
returns DATETIME
as begin
    declare @firstOfMonth VARCHAR(20)
    SET @firstOfMonth = CAST(@Year AS VARCHAR(4)) + '-' + CAST(@Month AS VARCHAR) + '-01'

    declare @currDate DATETIME
    set @currDate = CAST(@firstOfMonth as DATETIME)

    declare @weekday INT
    set @weekday = DATEPART(weekday, @currdate)

    -- 7 = saturday, 1 = sunday
    while @weekday = 1 OR @weekday = 7
    begin
        set @currDate = DATEADD(DAY, 1, @currDate)
        set @weekday = DATEPART(weekday, @currdate)
    end

    return @currdate
end

I'm not 100% sure about whether the "weekday" numbers are fixed or might depend on your locale on your SQL Server. Check it out!
Marc
Answer: Rather than a Holidays table of days to exclude, we use the calendar table approach: one row for every day the application will ever need (thirty years spans a modest 11K rows). So not only does it have an is_weekday column, it has other things relevant to the enterprise e.g. julianized_date. This way, every possible date would have a ready-prepared value for first_working_day_this_month and finding it involves a simple lookup (which SQL products tend to be optimized for!) rather than 'calculating' it each time on the fly.
Answer: We have dates table in our application (filled with all dates and date parts for some tens of years), what allows various "missing" date manipulations, like (in pseudo-sql):
select min(ourdates.datevalue)
from ourdates
where ourdates.year=<given year> and ourdates.month=<given month>
    and ourdates.isworkday
    and not exists (
        select * from holidays
        where holidays.datevalue=ourdates.datevalue
    )

Answer: Ok, at a first stab, you could put the following code into a UDF and pass in the Year and Month as variables. It can then return TestDate which is the first working day of the month.
DECLARE @Month INT
DECLARE @Year INT

SELECT @Month = 5
SELECT @Year = 2009

DECLARE @FirstDate DATETIME
SELECT @FirstDate = CONVERT(varchar(4), @Year) + '-' + CONVERT(varchar(2), @Month) + '-' + '01 00:00:00.000'

DROP TABLE #HOLIDAYS
CREATE TABLE #HOLIDAYS (HOLIDAY DateTime)

INSERT INTO #HOLIDAYS VALUES('2009-01-01 00:00:00.000')
INSERT INTO #HOLIDAYS VALUES('2009-05-01 00:00:00.000')

DECLARE @DateFound BIT
SELECT @DateFound = 0
WHILE(@DateFound = 0)
BEGIN
    IF(
        DATEPART(dw, @FirstDate) = 1
        OR
        DATEPART(dw, @FirstDate) = 1
        OR
        EXISTS(SELECT * FROM #HOLIDAYS WHERE HOLIDAY = @FirstDate)
    )
    BEGIN
        SET @FirstDate = DATEADD(dd, 1, @FirstDate)
    END
    ELSE
    BEGIN
        SET @DateFound = 1
    END
END

SELECT @FirstDate

The things I don`t like with this solution though are, if your holidays table contains all days of the month there will be an infinite loop. (You could check the loop is still looking at the right month) It relies upon the dates being equal, eg all at time 00:00:00. Finally, the way I calculate the 1st of the month past in using string concatenation was a short cut. There are much better ways of finding the actual first day of the month.
Answer: Gets the first N working days of each month of year 2009:
select * from invoices as x
where
    datePayment between '2009-01-01' and '2009-12-31'

    and exists
    (
        select
                 1
        from invoices
        where
            -- exclude holidays and sunday saturday...
            (
                datepart(dw, datePayment) not in (1,7) -- day of week

                /*
                -- Postgresql and Oracle have programmer-friendly IN clause
                and
                (datepart(yyyy,datePayment), datepart(mm,datePayment))
                not in (select hyear, hday from holidays)
                */

                -- this is the MSSQL equivalent of programmer-friendly IN
                and
                not exists
                (
                    select * from holidays
                    where
                        hyear = datepart(yyyy,datePayment)
                        and hmonth = datepart(mm, datePayment)
                )
            )
            -- ...exclude holidays and sunday saturday

            -- get the month of x datePayment
            and
            (datepart(yyyy, datePayment) = datepart(yyyy, x.datePayment)
             and datepart(mm, datePayment) = datepart(mm, x.datePayment))

        group by
            datepart(yyyy, datePayment), datepart(mm, datePayment)

        having
            x.datePayment < MIN(datePayment) + @N -- up to N working days
    )

Answer: Returns the first Monday of the current month
SELECT DATEADD(
    WEEK,
    DATEDIFF( --x weeks between 1900-01-01 (Monday) and inner result
        WEEK,
        0, --1900-01-01
        DATEADD( --inner result
            DAY,
            6 - DATEPART(DAY, GETDATE()),
            GETDATE()
        )
    ),
    0 --1900-01-01 (Monday)
)

Answer: SELECT DATEADD(day, DATEDIFF (day, 0, DATEADD (month, DATEDIFF (month, 0, GETDATE()), 0)  -1)/7*7 + 7, 0);

Answer: select if(weekday('yyyy-mm-01') < 5,'yyyy-mm-01',if(weekday('yyyy-mm-02') < 5,'yyyy-mm-02','yyyy-mm-03'))

Saturdays and Sundays are 5, 6 so you only need two checks to get the first working day


How can a lens combination take the image of the first lens as a virtual object for the second lens?

Question: When two lenses are in combination, what logic is it to take the image of the first lens (which is not formed in real) as a virtual object to the second lens?
Comment: What does "real" mean ? (rhetoric question) The light rays exist before and after what you're calling the "image". The "logic" is just a mean of calculus/drawing.
Answer: You're mixing reality with the process of image formation.
The object v is an auxiliary object when we perform calculations via stage 1 and stage 2. But actually, what really happens is that the rays bend a little bit after lens 1 and then they tilt again in the second lens. The result is the image $v1$ formed there.
The thing is that we calculate it in two steps, and we say that, for all practical purposes, it is like if we only had lens 2, and LIKE IF the object were v, but this is only an auxiliary reasoning.
Answer: Implicitly, this is what happens when we look at an image through a magnifying glass (a convergent lens).
When one looks directly at an image which is in a plane $P$ at a distance $x$ from one's eye, an image of the object is formed on the retina. If the object is not too close, the lens in the eye is strong enough to form a clear (focused) image on the retina and we see the object clearly.
When one looks at the same image through a magnifying glass, one looks at a bundle of rays (a bundle of parallel rays is the image it located precisely at the focus of the lens). In this case, it is easier for the eyes to form a clear image on the retina, because the eye's lens is not dealing with divergent rays coming from the points of a real (close) object, but with a bundle of parallel rays seemingly stemming from a virtual image of the objet located at an infinitely remote location further away from the eye.

In other words, the intermediate image, real (as in Newton's telescope) or imaginary (as in Galileo's binoculars) is just a mathematical device, an artefact, an intermediate construct, an abstraction aimed at solving a problem by a method of « divide to conquer »: splitting a complex problem into smaller, simpler problems which can be tackled separately and merged in a later stage to provide the final answer to the problem.


Mail freezes when saving message as draft

Question: Ever since upgrading to Mountain Lion, I noticed Mail often freezes up for a good 5-10 seconds at a time in the middle of typing. This happens constantly, and every time I notice it says "Saving Message". Unfortunately, it chooses to do this every time I start typing, and I often stop typing when I don't see the text appearing, so it takes me forever to compose a message of decent length. How do I fix this?
Answer: Apparently this has to do with the draft email being saved to server. As a workaround, try disabling "Store draft messages on the server" in Mail.app Accounts settings.
Comment: I'm not 100% positive, but that seems to have worked. Thanks! :D


How does a GM calculate opening and how many moves in advance?

Question: How does a GM make his opening repertoire and how does he calculate his moves in advance.Can he calculate 20 moves in advance base on his opening?
Answer: They don't calculate the common openings, they know them by heart, at least the main lines, and the possible refutations, should the opponent deviate from the main line.
For the less common openings, they might remember things not as deep as the often playable ones. Still, it's like 10-15 plys for something obnoxious and could be as much as 20-30 plys for the most common ones.
Answer: GMs have all the common opening memorized, sometimes to a very deep level.  In this regard, they are not calculating at all. Once they are out of their book, the depth of calculation is based upon the complexity of the board. When there aren't many pieces on the board, they don't always calculate so much as know that a certain situation is a win if they following certain principles.  In the middle game, 8 moves would be common, but the GM knows how to quickly remove from consideration variations that don't look promising. When they calculate deeper it is because they don't waste energy on bad variations.
Answer: It depends, strong grandmasters might know tremendous amounts of lines by heart. Weaker GMs who no longer drill openings will forget majority of lines sooner or later but they will still be very good at recognizing strategic patterns and in making practical decisions. They will still know how to lure much weaker opposition into mess they will understand better while they will be able to limit seriously power of younger guys with better theoretical knowledge by sidestepping dangerous lines and limiting possible home preparation dangers. It's not that much about calculating in openings I guess.
Answer: When Richard Reti was asked how many moves ahead he calculated, his answer is said to have been "One, sometimes two". This is probably correct, if by "calculate" you mean examine all alternatives and be sure of the result.
This is not what grandmasters do. What they actually do, nobody knows, not even them.


Can I use my Yongnuo YN-E3-RT II speedlight Transmitter with a Godox AD200?

Question: I'm looking to buy some speedlights/strobes but I really do not want to buy all new transmitters and receivers when I have the Yongnuo set. Will any strobes/speedlights from the Godox series be compatible ? If so, what kind ? If not, what is compatible with the Yongnuo trasmitter other than the Yongnuo YN200.
Comment: You won't need to buy any Godox receivers, just one transmitter. Pretty much all of the current Godox lights have Godox receivers built in.
Answer:
I'm looking to buy some speedlights/strobes but I really do not want to buy all new transmitters and receivers when I have the Yongnuo set.

Then stick with Canon RT-compatible gear.

Will any strobes/speedlights from the Godox series be compatible ?

No, not if you want any more control over the strobes/single-pin manual speedlights than remote firing. With the TTL speedlights, you'd need to add YN-E3-RX receivers to the feet. The built-in radio triggering is only compatible with Godox transmitters.
Radio systems of different brands are incompatible (with the exception of the FusionTLC Raven), and Yongnuo themselves make four separate incompatible radio triggering systems. [Well, strictly speaking, five systems, since they added the YN685EX-RF/YN32-TX for Sony...]

... If not, what is compatible with the Yongnuo [transmitter] other than the Yongnuo YN200.

Actually the YN200 is not compatible with the YN-E3-RT.  It's only compatible with the YN-560-TX Pro (and not the YN-622-TX; you can supposedly fire and M power control it with a YN-560-TX [non-pro] but not use TTL or HSS). Yongnuo was supposed to unify the 622 TTL and 560 manual triggering systems with the YN-560-TX Pro and firmware updates, but they never made firmware releases for the 622 gear available.
The YN-E3-RT is Yongnuo's clone of Canon's ST-E3-RT transmitter. It works well with any of Yongnuo's or Canon's RT speedlights. Theoretically, it should also work with Westcott FJ/Jinbei RT gear (FJ80/HD2-Pro; FJ200/HD200 Pro; FJ400/HD400 Pro) which are also RT compatible, but reports are that Yongnuo's RT reverse-engineering doesn't work with Jinbei's RT reverse-engineering. The only other directly RT-compatible strobe I know of is the Phottix Indra500LC monolight. No idea if it works with the Yongnuo RT gear, either.
If you want to get Godox lights, you're going to have to get a $60-$70 Godox transmitter to go with them. The main reasons most of us switched to Godox from Yongnuo is because Godox has a single unified 2.4 GHz radio system where the $60 TT600 works alongside the TTL/HSS TT685; supports not just Canon and Nikon TTL/HSS but also TTL/HSS for Fuji, Sony, MFT, and Pentax and that support is cross-brand; all the speedlights in the system are equipped with built-in radio transceivers; and there are multiple choices for bigger-than-speedlight options (like the AD200).
Yongnuo dead-ends you relatively quickly in expansion terms if you decide to stick with them; Godox doesn't. Hopefully in the future we can say the same about the Westcott FJ/Jinbei RT system.
Answer: Your YongNuo YN-E3-RT is actually a copy of the Canon ST-E3-RT, and is designed to control the Canon speedlights (and those built to be compatible with the Canon radio system (those with a "RT" suffix). You can use it for instance with a Canon 430EX III-RT or a YongNuo YN680-EX-RT (and many others).


Whether $y(t) = x(t/3)$ is a memoryless system?

Question: I am a newbie in signal and system, and feeling confused about the memoryless property, it says at the definition, if a system gives output only depends on present input, then its memoryless. So if at $t=3$, $x(1)$ is needed, whether this count as a memoryless system? Or it only consider the time shift like $y(t) = x(t-1)$?
Answer: You are trying to mimic what I did at time $t$.  You'll be $y$ for now, say I'm $x$.
Now suppose that our are mimicking my actions  with your own modification pattern (called $f$), at the very same time. Then, your location, depending on mine, is:
$$y(t) = f(x(t))\,. $$
Here, you only need the current observation $x(t)$ (hence, no memory).
Now, suppose that you are trying to mimic what I do at time $t$, but only three times slower ($t/3$). What you will do at $t=3$ (or $y(3)$), I did it at $t = 3/3$, or at one second ($x(1)$). You need memory.
Answer: In plain language, $y(t) = x(t/3)$ is "play back the input at 1/3 real speed".
That takes memory.
I don't see many systems like that.  I can't even conceive of a real example, unless it's part of some larger detection and identification system that first detects and then if there's a detection chews on the data to do an identification -- but even there I would expect that what you're really interested in is that the identification comes back with some delay, either fixed or stochastic.
Answer: In a memoryless system, the output at time instance $n$ depends only on the input at time instance $n$.
For example: $y[n] = |x[n]|$, for a very simple rectification or even $y[n] = \frac{1 + sgn(x[n]-v)}{2}$ where $v$ is a threshold value. When $x[n]$ is above $v$, the output is 1, otherwise it is zero.
The minute an output needs more time instances to calculate, you have a "system" with memory.
This is true whether your system tries to reference an adjacent time instant (e.g. $n-1$) or not (e.g. $n-2, n-8, n+4$). Even if such a system did not need $x[n-1]$, it would still have to have a mechanism to "skip it" to get to $x[n-2]$ and the rest, therefore, it would still need memory.
Take for example a very simple two-tap moving average filter: $y[n] = \frac{1}{2} \left ( x[n] + x[n-1] \right )$. Here, to produce one output at $n$, you need to know the $x$ values at $n$ and $n-1$. And when you end up with a difference equation like this, you will also most likely need to define some initial conditions.
For example, if you were to start processing $x$ from time instance $n=0$, you would obviously need $x[n-1]$ which is undefined (yet). You can still produce $y[0]$, as long as you were to specify something like $x[-1]=0$. This is exactly how you achieve "seamless" filtering when you apply filters to frames of samples. Say for instance that you want to filter two batches of 100 samples. For the first batch (where $n \in [0 .. 99]$), you set $x[n-1]=0$ (for $n=0$) but for the second batch (where $n \in [100..199]$, the $x[n-1]$ of the second batch is the $x[99]$ of the first batch. If you keep saving this "filter state" as you go along, you can realise filters in an "online" way.
"Memory" is not something to be associated with discrete systems only. In continuous systems for example, it would show up as a sum over a time interval as it happens when you consider the output of components such as capacitors and inductors.
Hope this helps.


write a workflow, that extracts some fields from my list

Question: I am attempting to write a workflow, that extracts some fields from my list and write those to an excel spreadsheet. Upon completion send an email to me with excel spreadsheet attached.
Comment: I don't have a great deal of experience in this, but I'll say this.  In SP Designer it is possible to create emails that imbed 'field:value'.  Therefore I imagine you might be able to do this.  One thing I would mention is that there is a useful tool in the List Settings, it is called 'Export to Excel' - it might be worth you exploring this in case it can be useful for you.  Perhaps using pivot tables in Excel could provide you with something useful too?
Answer: In O365/SP Online, you can do this using Flow - the new no/low code building block way to create workflows, including exports and notifications.
You can create this workflow in SP Designer for SP 2016/2013/2010, etc. The SP 2007/2010/2013 workflow options are predefined and limited.
Process-wise, your list already has the information that you want, so you'd be creating redundant data with a new spreadsheet on each workflow launch, then need to manage all the separate spreadsheets.
Another option - since the list is your data source - create a view on your list that shows the desired fields, and set up an alert to notify you when new items are added, so you're not replicating content.
Good luck!


Searching for files with parenthesis in Google Drive

Question: As Google Drive seems to create duplicate files with a " (1)" at the end, without the quotes, when it's not sure how to resolve conflicts, it would seem sensible if you could actually search for filenames containing parenthesis in the Google Drive application.  I have tried most things I can think of and tried searching a few forums, asking ChatGPT and the web in general to no avail... Anyone got a clue?
Answer: Had the same issue, but the real problem is that Drive, in the browser, allows duplicate file/folder names — so they don't actually include the "(1)" as far as I can tell.
I got around this by going to the Drive folder locally on my Mac (assuming you installed the desktop client) and searching for <code>"(1)"</code> (include the quotation marks) in Finder. Then, after spot checking to make sure the results were truly duplicates, I deleted all the resultant folders.
Voila.


Set Billing Address to be Not Required in Contribution Page

Question: Authorize.net does not require a billing address. How can I configure my CiviCRM to also not require that on a Contribution page?
Answer: I am surprised that Authorize.net does not require a billing address!  I don't recall ever seeing that.
With that said, I would recommend you still require billing addresses.  Right now the volume of fraudulent credit card transactions on non-profit sites seems to be skyrocketing and anything you can do to protect yourself would be prudent. The last thing you want is to have Authorize turn off your account due to fraud and you won't get any contributions then!
Answer: Does this issue correlate, ie do you have some fields that are required and are in the Billing Block and not otherwise available to the user via a profile? 15118
Only suggesting it as it just came up here
Comment: or possibly related to https://issues.civicrm.org/jira/browse/CRM-17082 ?
Comment: No, none of these are related. My boss just wants the billing address to be NOT required to make it easier to donate, that's all.


Centripetal & centrifugal forces

Question: If there are no centrifugal forces in reality then how to explain weight loss due to rotation of earth or dynamic balancing of a rotating mass?
Answer: The centrifugal force is one of the fictitious forces that lets one use Newton's laws in a domain (a non-inertial frame) in which they do not quite apply. There's always an explanation to Newtonian phenomena taken from the perspective of an inertial frame in which those fictitious forces do not exist. In some cases such as predicting the weather, using an inertial frame results in a numerical mess. The explanation from the perspective of an inertial frame still exists, but nobody uses it in the case of predicting the weather.

If there are no centrifugal forces in reality then how to explain weight loss due to rotation of earth or dynamic balancing of a rotating mass?

This is not one of those cases. The inertial explanation is easy. Consider a person of mass $m$ standing still at sea level at the equator. That person undergoes uniform circular motion at a radius $r$ of 6378 km from the center of the Earth and with an angular velocity $\omega$ of one revolution per sidereal day. This means the net force acting on that person must necessarily be non-zero. It is in fact $m r \omega^2$, directed toward the center of the Earth.
The only real forces acting on the person are the inward gravitational force, directed to the center of the Earth and the outward normal force, directed away from the center of the Earth. To yield a net inward force of $m r \omega^2$, the inward gravitational force (which can't be felt) must exceed the outward normal force (which can be felt) in magnitude by exactly this amount ($m r \omega^2$).
Comment: This sentence is confusing "There's always an inertial frame answer to any question in which those fictitious forces appear to be essential." The phrase "inertial frame" is used as an adjective to the word "answer" but reads like the object of the sentence. I suggest to connect the words with hyphen as  "inertial-frame-answer".
Answer: The centrifugal force is a inertial force appearing in a rotating frame of reference. A fixed coordinate system on the surface of the earth is a rotating frame of reference. Thus a massive body on the surface of the earth experiences a centrifugal force leading to a reduction of its apparent weight which is strongest at the equator.
Answer: The earth, strictly speaking, is not an inertial frame of reference but it is quite a good approximation. Now coming back to your question, centrifugal force is a pseudo force which is assumed to be acting on every particle in an accelerated frame of reference. If the frame is accelerating with an acceleration a with respect to an inertial frame, then we apply a force -ma on each particle if we are working in the frame of reference of the accelerating frame. If the earth is rotating with respect to a fixed axis with an angular velocity w, then so is every particle on/inside earth with it. Thus if we are working from the earth frame of reference then we have to apply a force mw²r radially outward where r is the distance of the particle from the centre of the earth and m is it's mass. The net force on the particle decreases and hence the weight decreases.

Centripetal & centrifugal forces


Why Monero needs ring signature?

Question: I am looking through the whole Monero privacy system, wondering why Monero needs ring signature? One can use stealth address to protect the identities of both sender and receiver.
Suppose the longtime public and private keys of sender are $ltsk=(x_1,x_2)$ and $ltpk=(g^{x_1},g^{x_2})$, the one time public key and private keys for one UTXO coin are $otpk=(pk=g^{x_1}g^{H((g_{x_2})^r)},R_{ot}=g^{r_{ot}})$ and $otsk={x_1+H(R_{ot}^{x_2})}$, and the lone time public key for receiver is  $ltpk'=(g^{x'_1},g^{x'_2})$ (may be many receivers).
If the sender needs to transfer this coin to the receiver, it just needs to use the $otsk$ to sign this transaction since $otsk$ is only known to the sender (the signature scheme can be ECDSA or Schnorr). Since anyone cannot link $otpk$ to $ltpk$, this will protect the sender's identity. So I think the ring signature is no longer needed.
For the privacy of the receiver and the amount is consistent with the above system. Meanwhile, the key image is also consistent with the above system.
Can anyone tell me why the ring signature is needed here? Thank you!
Comment: This SE site does not have the MathJax extension (as you can see from your rendered post). Please remove the MathJax formatting.
Answer:
Why Monero needs ring signature?

So that transaction outputs are not traceable.
From https://www.getmonero.org/resources/moneropedia/ringsignatures.html:

... ring signatures ensure that transaction outputs are untraceable. Moreover, there are no fungibility issues with Monero given that every transaction output has plausible deniability (e.g. the network can not tell which outputs are spent or unspent).
Comment: Sir, I know the ring signature is to hide the source of the coin the sender spends. However, I think the goal of Monero is to hide the identities of the sender and the receiver. To accomplish this goal, only the stealth address is needed, this will make the whole system less complicated.
Comment: The "goal" of Monero is private, untraceable digital cash. Without ring signatures in Monero, coins could be traced, and thus lose fungibility, a key property of cash.

Why Monero needs ring signature?


Plant is bending and getting die

Question:
Suddenly my plant start bending to one side
I think the stem is weak and from weak stem it is shedding off
Will my plant can thrive again if i cut the upper bending part
Or some other measure should i take
Answer: Use a better potting medium.  It appears you are using soil from your garden.  Which is fine for the ground, but not for a pot.  A pot is an artificial environment.  It has different requirements.
It appears your plant is very dry.  Start by giving it some water to drink.  If you plant has any chance of survival it will start to perk up a little bit really soon.   But, not completely.
Next pot it in something that is called Potting Mix or Grow Mix.  These are the two words you are looking for.  These are soil made for plant pots.  You need to be very gentle repotting it this time of year, but it can be done.
Make sure you start with a pot with holes in the bottom. If it does not have hole, drill holes of buy a different pot.
Wash all the old soil off your plants roots.  Make sure you are supporting your plant while you are doing this.  Don't let the part bending bend anymore.
Next fill the bottom of your new pot with potting mix.  While holding your plant in place you will gently add the new soil around its roots.
Make sure you do not plant it any deeper than it is planted at this time.  Once it is planted.  Put a bamboo or metal stick in the pot as a stake.  Ask the garden centre for a stake for a potted plant.
If you can gently see if you can prop up the bent part. Do not force it.  Only move as much as the plant will easily move. If you can straighten it stake it in place.  If you can only prop it up part of the way stake it part of the way.
The side that the bend is on, should be the side opposite to sunlight.  The plant will want to stand up and grow towards the light.  Make sure its on the opposite side so it will stand up to get to the light.
This may not work. There may end up being a bend in your plant for the rest of it's life.
This may not save the plant.  So, think about how much you like the plant, before spending this money on a plant that may not survive, when you can probably buy a new plant for close to the same cost.

Plant is bending and getting die


Minimum force to stand on flat ground and climb stairs?

Question: What is the minimum force that we need to lift our body to walk up a flight of stairs?
Let's say I weigh 50 kg and I walk up a flight of stairs. What the minimum force I need to apply to stand straight on flat ground and to climb the stairs?
Answer: The minimum amount of work required to lift a stationary object of mass $m$ through a height $h$ is $mgh$ where $g$ is the acceleration due to gravity - this is the difference in potential energy between height $0$ and height $h$.
This can be achieved with a force that is as small as you like. This is because work is force times distance (where we measure distance parallel to the direction of the force). So you can do the same amount of work by moving a small force through a large distance as by moving a larger force through a smaller distance.
A device that magnifies force, converting a small force over a large distance into a larger force over a smaller distance is called a mechanical advantage device. Examples are levers, block and tackle systems, and probably the simplest example, the inclined plane.
So if you built a long, smooth inclined plane to the top of the stairs, and you made the angle of the plane to the horizontal very shallow, then you could climb the stairs by exerting very little force (although it might take you a long time). This is, of course, the principle behind wheelchair ramps.
Answer: To climb stairs, you need to start with an upward force slightly greater than your weight to produce an upward acceleration (and velocity).  Once you get moving, the upward force must support your weight (in Newtons) (shifted from leg to leg).  As you go up, this force is acting through a vertical distance and doing work (which it does not do on a horizontal walk).
Answer: While you are climbing at a uniform velocity, the force is exactly the same as if you were standing still. As you begin the climb, you accelerate, which requires a force applied in the direction of the climb (inclined at the stair's angle); this force vector adds to the vertical force vector due to gravity to create a net force vector. Once you have established the climbing velocity, the angled force goes away; only the vertical gravity force remains.
What you feel while climbing stairs which you do not feel while standing still is the work being done as the force against gravity is being applied over the height you are climbing. It is not an increase in force but an expenditure of energy.


When conjugating adjectives, can we use the normal form of the adjective and use the copula です to indicate its form?

Question: This is specifically for い-adjectives, as な-adjectives work this way.
For example, when I want to say something is not delicious I'd usually say おいしくない.
Would it be possible to use おいしい じゃありません and would it mean the same thing?
Comment: Short answer: no you cannot do that.
Comment: おいしいじゃありません(?) might mean "It's delicious, isn't it?"
Answer: It would mean the same thing, but wrong in terms of grammar.

おいしくない:

Question おいしくない? (Delicious, isn't it?) valid
Statement おいしくない (Not delicious) valid

おいしいじゃありません:

Question おいしいじゃありません? (Delicious, isn't it?) valid
Statement おいしいじゃありません Not valid

The question "おいしいじゃありません?" is a unique edge case, and you might never use it in your life.
The statement "おいしいじゃありません" looks/sounds wrong although the message is clear you are not enjoying that meal.

Possible statements to deny おいしい:

おいしくありません

Following works too:

おいしいごはんではありません
おいしいとは思いません

Edit:
The above are basics. Hate to add complexity but there is yet another edge case where one is happy with the meal and say:

Statement おいしいじゃありません (Isn't this delicious)
Statement おいしいじゃありませんこと (Isn't this delicious)

This carries the same logic as the question, but is not a question. It's somewhere between a rhetorical question and a firm statement. These are advanced expressions which may be used with enough context and correct pronunciation.


Air Compressors never have air pressure gauges here so what is the easiest way to achieve a certain tire pressure?

Question: I just checked a high end bicycle shop and it doesn't have air pressure gauge on the air compressor outlet( or anywhere) and the local shop doesn't have one at the end of long outside one- it is doubtful any bicycle shop has one. They also don't sell bicycle pressure gauges. It is against their religion or something to ensure the bicycles achieve a certain tire pressure- standard is all you get. I can buy air pressure gauges online but I do overpressure them leak it back or are there a air pressure controlling intermediate valve?
Comment: I'd just buy a floor pump with pressure gauge. If the bike shop's compressor inflates to a high (but still safe) pressure you could get an air pressure gauge (e.g. LifeLine's digital pressure gauge or Topeak SmartGauge D2) which displays tyre pressure and has an air release button.
Comment: What air pressure level are you trying to achieve?
Comment: I don't know about your shop, but it's not uncommon to use compressors for initial inflation (perhaps to thumb-firm on a road bike) then finish off with a pump.  A major reason for having a compressor at all is seating tubeless tyres.  Anyway the bike shop won't know what pressure you want to run at for your weight and the terrain
Comment: The commonly used Park Tool inflator has a gauge. Interesting to see they aren't using one that has a gauge.
Comment: In a rare exception, the hand pump at a rather upscale bicycle shop had a pressure gauge. Shop purchased hand or foot pumps don't have pressure gauges.
Answer: The best way to get a specific tire pressure is to carry your own air gauge.
Through experience you can develop a feel for how much pressure is in the tire by squeezing and then dial in the exact pressure with your gauge.

Put air in the tire until it seems to be about 75% full
Check it with the gauge
Put in a little more air
Repeat step 2 and 3 until it's dialed in
If you put in too much let it out in short bursts - check it with the gauge after each burst.

After you build some experience it goes pretty fast.
It would be nice if all public tire air supplies had a gauge. The few I've used were inaccurate so I don't trust other people's gauges. Get your own gauge - don't get a cheap one.
For home it is possible to get a floor pump with an accurate gauge built in.
Comment: +1: Your own gauge does not need to be particularly accurate, as long as it is consistent. Digital gauges will be both, all but the cheapest mechanical ones are usually consistent.
Comment: @mattnz It seems like accuracy is important as well as consistency. I don't want a gauge that is always reading 10 lbs too low or too high.


How can I improve my musical ear so I can detect notes on different instruments?

Question: I'm a beginner in learning music (I'm learning Persian lute). How can I detect scales, notes, etc. by ear? I'm awful at that but I guess that's true for every beginner, right?
I've heard EarMaster software helps. Is it any good?
Comment: Detecting scales is a hard thing even for pros.
Answer: You're correct, in that this becomes easier with training and/or experience.
If you are talking about identifying notes and chords, there are two possibilities. If you want to be able to identify the note, chord or scale with no references, you're talking about absolute pitch. It's also called perfect pitch. Some people have the ability to hear a note, and identify it with no other reference points. Absolute pitch is not all that common, although you'll meet a few people with that ability if you hand around musicians long enough. If you want to know more, search for perfect pitch or absolute pitch.
The other possibility is relative pitch. This is the ability to identify a note/chord/scale, with some other reference. If you play me a Bb, I can sing an F. This is much more common than absolute pitch, and can be trained. This may be contentious, but I think it's more important than absolute pitch for playing music.
It's worth observing that absolute pitch is not 'opposed' to relative pitch; you can easily have both. The jury seems to be out on whether you can learn absolute pitch, but you can definitely improve your relative pitch. This will happen naturally as you play more, but intentionally training it is a great idea.
Finally, if you're not interested in the specific pitch, it gets even easier. Most musicians will be able to tell a major scale from a minor scale, with no external reference whatsoever. I suspect a Persian lute is not going to be playing Western major and minor scales, but I hope the principle still applies. You'll gain this ability as you play more. You can certainly break down a series of notes, determine the intervals, and see if they form a major or minor chord/scale, but with some practice this will happen automatically. You won't even think about intervals any more; you'll just know that collection of notes sounds major or minor.
In summary; You'll get better at this as you play more. Ear training is never a bad thing, so go for it if you have the time. I have no experience with that specific software package, so I can't offer any feedback there.
Answer: EarMaster is a very powerful and excelent software but nothing can be better than practicing while playing. Do it the way many people do it. Find a song you like and listen. Try to find the notes that are being played. Make up a tune in your head and find those notes on your instrument. Practice everyday and in some time you'll be much better at it.
Answer: It is possible to teach yourself to recognize notes by hearing them. However, for most people this is extremely difficult, in some cases- impossible, and usually take years to master. There are people for which it comes naturally- they can remember notes easily and are sort of 'born' with it. This is called absolute hearing (at least this is what I know it as, it might not be the real term for it.) Most people have relative hearing, meaning they can remember the intervals between the notes of a melody and hear/correct mistakes made within the intervals, but if you transpose the whole song 1/2 step lower they won't notice. Don't worry about memorizing and recognizing the notes too much. Do, however, learn the distances( number of steps) between the notes in major (whole whole half whole whole whole half) and minor (whole half whole whole half whole whole) scales and learn tell them apart from each other. This will help you with playing, especially with identifying your mistakes.
Answer: Music is all about listening and constant practice. To develop your hearing, listen to songs and sing along with the melody.


Cannot select partition during windows 7 installation

Question: I am facing a strange issue where I cannot select any partition for windows 7 installation. The installation force selects the unallocated space.
I had same issue with Windows 10 installation.
https://youtu.be/XSw60REkef0
Answer: The existing partitions probably contain an operating system. If you try to install Windows over top of an existing Windows installation, it is called an "upgrade install" and you can't do that if you run setup from the boot disc. An upgrade installation can only be performed by starting setup from within the running operating system.
To install windows from the boot disc, you will have to choose the free space or erase the existing partitions and allow Windows setup to create new ones. In this case, you should simply erase ALL partitions and then click Next. Windows will automatically create the necessary partitions at maximum size and continue.
Obviously, if you erase existing partitions it will also erase all the data on them.
Comment: I need to be able to select the partition in order to format it. The wizard should display the error instead of force selecting the unallocated space. And no, I am not trying 'Upgrade Install'.
Comment: Do you, or did you have Linux installed on any of those partitions? If Windows setup can't recognize the file systems it won't let you do anything with them. You can try deleting the partition from the command line by pressing `SHIFT-F10`. Once at the command prompt you can use diskpart to manage the partitions. Once you delete the problematic partition, you might need to reboot and start the Windows setup again. A better solution might be to use a partition manager boot disc that can re-organize the data and give you one chunk of free space you can use.
Comment: I should also point out something I overlooked. One of those partitions is a logical partition, and I don't think you can have a logical partition without a primary partition. So, this might also have something to do with it and is likely to keep you from removing the primary partition. Instead you can just try reformatting it NTFS from the command prompt, but first you'll have to force mount it to a drive letter with diskpart.
Comment: Very strange, I was able to select the partition this time. :o WHYYYYY?
Comment: I feel like a dumb now. It was related to sticky space key. :|


Wrapping up Asp.net Framework 4.0 in 3.5

Question: I am working on an application in VS 2010 and using Asp.net framework 4.0 which i just migrated from Framework 3.5. The reason i had to migrate it to 4.0 is, i have a third party toolkit dll which is built in Framework 4.0, so in order to include it i had to change target framework of this project to 4.0. As, this project is being referred from other projects ans so on.., i end up  converting whole application to framework 4.0. Every thing worked okay but as the application is using spring.net also, after successfully building the application, i found broken controls on almost all the pages. i am getting java script errors (about undefined control)for usercontrol PopupDatePickerControl we are using in the application. i downloaded and included latest version of Spring.net.  i have no idea what is causing this problem. Please help if any one has experience working with this combination of framework 4.0 and spring.net? OR there is any way out to wrap up Framework 4.0 into 3.5. so i don't have to do this Migration.
Thanks!
Comment: Can you trace with for instance Fiddler/Firebug if the javascript files your controls are requesting are not delivered. Imho this is due to a misconfiguration in your web.config (httphandler, httpmodule, axd).
Answer: Sounds like a shot in the dark on so many levels.  It's probably not the combination of 4.0 and Spring.NET, unless you aren't referencing the correct Spring.NET dlls.  Can you post parts of your IoC configuration and a rough outline of your app's architecture?
Also, what is the other third party toolkit you mentioned?


Connect to an IOS IBAction which is not at a "valid connection destination"

Question: I have been spending days to make connection from a button on the storyboard to a new NSObject class in an IOS project. Methods I used in OS X no longer work in IOS.
I have no trouble connection the button to the IBAction on the original UIViewController class. According to the Apple documentation my new class is not a "valid connection destination".
To work around the issue I tried to call the method in the new class from the UIViewController class. I tried notification and delegate schemes, using the posts on Stack Overflow, but could not get them to work.
The closest I came linking to a +method in the target class, such as
+ (void) startToneGenerator
{
    NSLog(@"Arrived in startToneGenerator");
//        [self startPlay:nil];
}

However, from inside that method I can not call the -startPlay in the same class. Because the -StartPlay class is part of an audio unit construct I can not change it to a +starPlay class without breaking the audio unit.
Can anyone point me to some documentation which describes what "valid connection destination" really means, and how to make the attempted connection a valid one.

I used the method suggested in answer 1 in OS X, where it does work, but it no longer works in IOS.
I am restating the code you clarify the problem.
// code in VC

- (IBAction)RunPauseStop:(id)sender
  {
   NSLog(@"arrived in RunPauseSTop");   // OK

   [uToneGenerator testMethod]; // OK
   //  [uToneGenerator startPlay:self]; // crashes
}

// code in uToneGenerator

+ (void) testMethod
{
NSLog(@"arrived in <testMethod>");   // OK
//  [uToneGenerator startPlay:nil];  // crashes
}

- (IBAction)startPlay:(id)sender
{
NSLog(@"arrived in <startPlay>"); // Don't get here
}

The line [uToneGenerator startPlay:nil]; compiles (with a warning) but crashes with:
2012-03-06 13:20:25.509 Tinnitus Tamer IP[863:f803] +[uToneGenerator startPlay:]: unrecognized selector sent to class 0x6c40
2012-03-06 13:20:25.509 Tinnitus Tamer IP[863:f803] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[uToneGenerator startPlay:]: unrecognized selector sent to class 0x6c40'
calling from testMethod; compiles but crashes with:
2012-03-06 13:22:31.413 Tinnitus Tamer IP[885:f803] +[uToneGenerator startPlay:]: unrecognized selector sent to class 0x6c44
2012-03-06 13:22:31.414 Tinnitus Tamer IP[885:f803] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[uToneGenerator startPlay:]: unrecognized selector sent to class 0x6c44'
I noted that the error message can not find +[uToneGenerator startPlay:, but the method I am trying to call is -[uToneGenerator startPlay:

uToneGenerator *utg = [[uToneGenerator alloc]init]; works OK. In spite of the compiler warning "NSProject may not respond to 'startPlay'.
Thanks for helping me out. Much appreciated. I really was stuck.
Answer: You need to call whatever class method you want inside the IBAction method in your VC:
- (IBAction)myButtonPressed:(id)sender {
     [MyClass myClassMethod];
}

Answer: If you want that code to work you must declare - (IBAction)startPlay:(id)sender with a +. Otherwise you will have to make an instance of your class:
uToneGenerator *utg = [[uToneGenerator alloc]init]; //or whatever you use

and then use that to call your startPlay method:
[utg startPlay:self];

Hope it helps.