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I am having difficulty in understanding about weighted linear least squares. Could anybody explain me instead of minimizing the residual sum of squares why we need to minimize the weighted sum of squares? Further, I want to know about the term weighted? Although I have gone through some wiki notes but I am not able to understand. Thank you very much for the help. | 1 |
I just downloaded and installed MikTex and TexMaker today, and was wondering if you have any advice. I'm starting to read through various wikipedia tutorials, and other guides, but videos would be an immense help! | 1 |
A and B worked together to complete a certain task in three hours. If A works alone, he can complete the task in five hours. If B works alone, how much longer will it take him to complete the task? I have the answer to this question, but I just don't get how that works. Please help me out. | 1 |
Most important theorems in measure theory do not assume the completeness of measure spaces. Monotone convergence theorem, Dominated convergence theorem, and Fubini's theorem, to name a few. So I wonder if the completion of a measure space is necessary. In particular do we need to consider Lebesgue measurable sets which are not Borel sets? | 1 |
When i put a pencil in the middle of a paper and rotate it very fast, whatsoever is written on it, will appear in concentric circles. What is the reason behind this phenomenon and what is it called? | 1 |
The variational method, as it pertains to quantum mechanics, is used to approximate the energies of a particular system. Is it possible to use the same variational method to approximate the eigenvalues of other observables? | 1 |
I have been searching in vain for statistics about the runtime of pdfTeX, LuaTeX and XeTeX. My impression is that (ordering by increasing runtime), LuaTeX > XeTeX > pdfTeX, but exactly how big is this difference? | 1 |
In referring to a particular femme fatale, I described her "femme fataleness." That is "ungrammatical" (I believe) but got the point across. Is there a correct term for this particular attribute? If so, what is it? | 1 |
I'm struggling to understand how to define multiplication and addition, now that I've been told that multiplication is not just repeated addition. It seems that the axioms for the two are identical, save that multiplication is said to not have an inverse for the additive identity. Doesn't this imply that multiplication cannot be defined without an addition? | 1 |
I know that any Riemann integrable functions have at most countably many discontinuities, and similarly, any bounded functions with countable number of discontinuities are Lebesgue integrable. But is it necessarily true that any Riemann integrable functions have at most countably many discontinuities? Thanks | 1 |
I see that you can use a Stern-Gerlach apparatus for massive particles that can be deflected, but that doesn't work for photons. What would you do instead to measure photon spin in a lab? | 1 |
I would appreciate it if you could explain to me the difference between implementing and executing in the context of the following sentence: The implementing agency(ies) for this project is UNEP and the national executing agency is the Department of Environment. | 1 |
Can you please clarify for me which is the correct answer to the following question: Do you often have visitors? a. Yes, pretty much every day b. Yes, quite often c. Not very often. | 1 |
As the title says it, I want to know how people find the work function of a metal without knowing the threshold frequency. Yes I've already searched on Google but I didn't find anything really relevant. I just found how to calculate Work function with threshold frequency. | 1 |
I was given a piecewise function, which happens to be continuous on some interval. It asks me to prove that it's Riemann integrable. I know that continuous functions are Riemann integrable, but is there a way to prove it for some specific function (without using that theorem that continuous functions are Riemann integrable)? | 1 |
For any graph G, prove that the line graph L(G) is claw-free. I have a fairly good intuition for this one but it's hard to put into words. I really need help with this one! I feel that I should use the pigeonhole principle... | 1 |
This integral comes from a physics book when calculating a field of an uniformly charged sphere (without Gauss' Law). It says that it can be done by partial fractions, but I cannot imagine how. | 1 |
Question: Prove that at any given moment, there exists a pair of diametrically opposed points on the equator of the Earth that have the same temperature. Use the Intermediate Value Theorem. Now I've been kinda struggling with how to deal with the Intermediate Value Theorem and I have no idea where to even start on this one. | 1 |
You can visualize a first-order Markov chain as a graph with nodes corresponding to states and edges corresponding to transitions. Are there any known strategies to visualize a second-order Markov chain, i.e. where transitions have two past elements and one future element? | 1 |
In graph theory, what is the difference between a cycle and a simple cycle? My impression is that a simple cycle is the same as a cycle except that you cannot repeat vertices. Is this correct? | 1 |
I have been searching in the literature, with no results, for the (Zero Field) Magnetic Susceptibility of BiSCCO, but I cannot find any article regarding that. Does someone have a reference that might be useful to me? Thanks a lot. | 1 |
Consider a recursive Mergesort implementation that calls Insertion Sort on sublists smaller than some threshold. If there are n calls to Mergesort, how many calls will there be to Insertion Sort? Why? Wouldn't this depend on the threshold, or is there another way to look at this? | 1 |
Does "feel committed to" require an infinitive or gerund complement? For example, which of the following is grammatical? I feel committed to following up on that. I feel committed to follow up on that. | 1 |
Even if Lebesgue measure and integration can be defined without using the extended reals, it might not be a very helpful formulation. My motivation for asking this question is that I'm curious about in which ways Lebesgue integration is an extension of Riemann integration, which doesn't necessarily use extended reals. | 1 |
The Cayley table tells us whether a group is abelian. Because the group operation of an abelian group is commutative, a group is abelian if and only if its Cayley table is symmetric along its diagonal axis. Sorry, but why is this true? | 1 |
What is the difference between pull over and pull away? I am still trying to get used to American English. It seems like if I do not understand the driving vocabulary I am going to fail in the driving test. | 1 |
What's the difference in the usage of these two adverbs continuously and continually? Here are some examples: a) She was told off for continually being late. b) It rained continuously for three hours this morning. c) The firemen worked continuously through the night. d) I'm afraid you continually make the same mistakes. | 1 |
Does adding the word "ok" to the end of a statement imply a choice instead of a command or order? Example: "Wash the dishes now". as opposed to "Wash the dishes now, ok?" Does this weaken your statement? | 1 |
The four major cities in the Netherlands, i.e. Amsterdam, Rotterdam, The Hague and Utrecht belong to the Randstad. What is the English translation for the Dutch word Randstad? I have found downtown but I wonder whether this is the correct translation. | 1 |
I was wondering about discrete metric space. Is it a proper metric space? I am trying to find some example of non proper metric space. I am not sure whether discrete metric space is proper or not. | 1 |
Possible Duplicate: Why is matter drawn into a black hole not condensed into a single point within the singularity? When we speak of black holes and their associated singularity, why is matter drawn into a black hole condensed into a single point within the singularity? | 1 |
I've heard a lot about the CJK package, so I want to give that a try. There is, however, no documentation for that package (see the link), nor do the available documentation files at CJK's website tell me anything about how to use the package. So how do I figure out how to use this package? | 1 |
In my physics textbook it describes the events at the beginning of the Universe. I'm confused about the order at a certain point. It says that at some point primordial helium is created, then it says that later atoms are formed. Isn't primordial helium made of atoms? Thank you :) | 1 |
Will we ever come up with non-gender specific pronouns and possessive pronouns for the English language? It seems that there are many new words in the English language every year, so why not gender-neutral pronouns? This would solve many problems, in literature and in everyday life. | 1 |
Which would be better to say? He reminds me of Dill from To Kill a Mockingbird. He reminds me of Dill in To Kill a Mockingbird. He reminds me of Dill of To Kill a Mockingbird. Also, which is more appropriate in a formal context? | 1 |
Possible Duplicate: What are your favorite English language tools? I have a question regarding the English language that is too general for this site according to the faq. OTOH, I don't know where to look for the answer. Is there a list of sites, books, etc. that are commonly used to answer questions? | 1 |
While playing around with cyclotomic fields, I started to wonder about taking the roots of unity in higher dimensional analogues of the complex plane. Are the roots of unity well defined in the quaternions, octonions, and other hypercomplex algebras? Are there higher dimensional cyclotomic fields, and if so do they have any interesting properties like unique factorization or interesting morphisms? | 1 |
Do the Law of Sines and the Law of Cosines apply to all triangles? Particularly, could you use these laws on right triangles? That is, could you use these laws instead of the Sine=opposite/hypotenuse, Cosine=adjacent/hypotenuse, and Tangent=opposite/adjacent rules to solve right triangles? I can't find this stated in any of my textbooks, nor has my instructor said anything about it, which I find odd. | 1 |
Is there any difference between the following two statements: I have to pay bills I have bills to pay Could you please tell us the difference between the above two statements and when to use them? | 1 |
I've always found it irksome when people form sentences such as "I'm done my homework." It is of my understanding that you are never done something, but rather you are done with something. Am I right to be bothered by this? | 1 |
I'm told at school that the Electromotive Force (e.m.f) of a battery equals the potential difference between the terminals of the battery when there is no current. How is that possible? How can there be a potential difference with no charge flowing? | 1 |
How do you exactly define what is and isn't a dimension? I heard somewhere that it is "anything you can move through" but if that is right, why wasn't time and space considered a dimension before Einstein? | 1 |
Connes's non-commutative geometry program includes an approach to the Standard Model that employs a non-commutative extension of Riemannian metric. In recent years I've heard physicists say that this approach does not hold significant interest in the physics community. Is this, in fact, the case? If so, why? I do not mean for this question to be argumentative, but instead would like clarification. | 1 |
We were taught at school that if we want to make something plural, we should add "s" at the end. Later on, I learned that there are uncountable nouns. Not so much familiar with it. Can you please give some examples? | 1 |
I learned how to use bibtex from the LaTeX wikibook, found here. They say that to compile a LaTeX file that uses bibtex, you need to call pdflatex once, followed by bibtex, followed by two more calls to pdflatex. I'm wondering: what's actually going on at each of these steps? Why do I need to run pdflatex and bibtex in that order? | 1 |
If physics is the study of the physical universe, wouldn't that mean chemistry, biology, neuroscience, zoology, history, economics, sociology, etc, wouldn't they all be subfields of physics? I believe they are. If anyone can convince me otherwise with a good argument, the answer will be accepted. | 1 |
I need to figure out this property of Hermitian / Orthogonal projections "A is a Hermitian projection if and only if it is an orthogonal projection" Your assistance will be highly appreciated. Thank You | 1 |
Photons travel at the speed of light. Is there a known explanation of this phenomenon, and if yes, what is it? Edit: To be clearer, my question is why do photons travel at all. Why do they have a speed? | 1 |
I'm having some problems determining which of the following is more grammatically correct: The season that I like the best is Winter or Winter is the season that I like the best I know that both are technically correct, but when would you use one over the other? | 1 |
One of the requirements of my English final includes removing all prepositions from a previously written essay. I'm having trouble getting rid of prepositions like "to", "in", "of", and other common preposition that seem like a requirement in writing. Could someone point me in the right direction? Thanks. | 1 |
I recently came across this proposition that the eigenvalues of a product of square matrices are invariant under cyclic permutation of the product order. Is there perhaps some group theoretic way of proving this proposition? I've tried a few cases and it seems to be true, but a direct proof has proven elusive. Or is a proof not so simple? | 1 |
I've read that the characteristic function of a probability distribution always exists because it's bounded. However, the characteristic function is still Taylor expanded in terms of the moments of a given probability distribution. Given the the moments don't necessarily exist, why is it that the characteristic function still exists? | 1 |
I'm trying to wrap my mind around the semantic differences between the words "Register" and "Apply". For example, are there any real differences between these two sentences: "I will apply for this event." "I will register for this event." What is the best way to think about the meanings between the two words? | 1 |
From my experience, it seems that although unstable is more commonly used, instable is often preferred in engineering and scientific contexts, e.g. "aircraft instability", "instable algorithm". Are there any differences in the implied meaning of the two terms? Should unstable be preferred? | 1 |
I saw a few groups on the web. A group's name is "Non alcohol ~" and another one is "Alcohol free ~". But I don't know the difference between "non alcohol" and "alcohol free". I think that "non alcohol" and "alcohol free" have the same meaning. Am I right? | 1 |
In fluid mechanics the terms 'pure straining flow' and 'pure rotational flow' are often thrown around (see e.g. here). I have tried looking for a formal definition of these two but have not been able to find one (or in fact anything you might call a definition). So how can we formally define these two terms? | 1 |
In the spin Hall effect, electrons with different spins accumulate in opposite directions without any external magnetic field. Broadly, the reason behind this is the spin-orbit interaction. But, the question is how? How does the spin-orbit interaction leads to this. A physical explanation will suffice. | 1 |
Is there any connection between fluctuation dissipation theorem and Kramers-Kronig relations? They are often described together under linear response theory but I do not see any exact connection (like one being special case of another). | 1 |
The force of gravity is constantly being applied to an orbiting object. And therefore the object is constantly accelerating. Why doesn't gravity eventually "win" over the object's momentum, like a force such as friction eventually slows down a car that runs out of gas? I understand (I think) how relativity explains it, but how does Newtonian mechanics explain it? | 1 |
I am trying to find the equation for the form that is in the picture. Basically it is an infinitely extending roller coaster loop. I just can not find the magic words in Google. Any suggestions? What is it called? What is the equation? | 1 |
When referring to a U.S. state in a formal document, is it correct to capitalize "State," or should it remain uncapitalized? For example: This school is accredited by the State of Maryland OR This school is accredited by the state of Maryland | 1 |
I have a doubt about the Hermite Spline. Is it the interpolation with the minimum value of curvature among the possible interpolative functions between two points? Is it possible to demonstrate it? Thank you very much! | 1 |
Dirac delta function can be defined in several ways. I know two definitions. One is as a distribution and the other is as a measure. I found many materials on the derivatives of delta function as a distribution. However, I couldn't find materials dealing derivatives of delta function as a measure. Could someone point me at any materials or explain it? | 1 |
Would you please tell me which of these four sentences is correct one? I am so confused with them :( Action movies are three times as popular as comedies for men. Action movies are three times more popular than comedies for men. Men watch action movies three times as many as comedies. Three times as many men watch action movies than comedies. | 1 |
I'm aware that the Milky Way has a dark matter 'halo' around it, presumably a spherically symmetric distribution. But I'm completely ignorant regarding the theories explaining dark matter... Is there any reason to not expect a star-sized object to also be made of dark matter? I know they'll be extremely difficult to detect, but I'm wondering if it's even physically possible to exist. | 1 |
How many triangles in this picture: I know that I can just count the triangles to solve this specific problem. I would be interested to know if there is a systematic approach to doing this that can be generalized to larger diagrams of the same type. | 1 |
I'm having trouble obtaining the answer for this practice-test problem. I'm taking the volume of the whole cylinder as if it weren't cut then subtract the portion cut off. But I'm not getting any of the answers below. Any hints will be greatly appreciated. Thank you all. | 1 |
After listening of some lectures of Leonard Susskind about black holes, he mentioned that conservation of information is one of the foundations of physics. After searching the web I cannot seem to find how we came up with this theory. Could someone explain how we know this is true and/or how did we come to this conclusion? | 1 |
According to a book I'm reading, the Fourier transform is widely used in quantum mechanics (QM). That came as a huge surprise to me. (Unfortunately, the book doesn't go on to give any simple examples of how it's used!) So can someone provide one please? | 1 |
I want to know if I can determine the time where the sun's azimuth is at a given value. In other words, I want a function that takes the sun azimuth along with longitude or time zone and outputs the time. Is there anything like this? | 1 |
After reading definitions of universal and k-universal (or k-independent) hash function families, I can't get the difference between them. Also, I couldn't find any examples of hash function families being universal, but not k-universal (it's written, that k-universality is stronger, so they must exist). Could you please clarify the subject to me, or give a good piece of literature/articles to read about it? | 1 |
A recent arXiv article measures the variation of gravitational potential in a local region around the solar system, and from that it tries to infer the mass density. Are there any valid counterarguments to their conclusion, i.e: that there is no dark matter near our vicinity? | 1 |
I rarely need the ancillary files TeX produces when compiling a document (.aux, .log, .out, .synctex.gz). In fact, I've only ever had to read the .log, and that's only a few times. Is there a way to write them to a separate directory, so that my working directory only contains .tex and .pdf files? | 1 |
I'm looking for a package in which you can create nice bar and/or line charts in LaTeX. Currently I'm plotting the charts in Calc (OpenOffice), export it to a PDF document, crop it and then including it as graphics. I reckon there should be some more efficient way of doing this, preferably entirely in LaTeX. | 1 |
In special relativity, when two observers move in respect to each other, each observes the other's clock tick slower. An observer floating in space far from gravitational fields, observes earth clock ticking slower; at what rate is the clock of the floating observer ticking as observed from earth? | 1 |
Where does the word "crack" originate from in the phrase "Give me another crack at that"? Curious to know if it's in reference to driving horses? Perhaps a derivative of "craic" in Irish? Or in a structural metaphor about material splitting? Cheers. | 1 |
Do you use a question mark when a sentence starts as a question but then turns into a statement? For example, "Can you explain this to me, because I don't understand the second part." "What did he just say, because I couldn't hear him over the noise of the television." I usually use a period but don't know if that is correct. | 1 |
I'm trying to use different distance metrics like Euclidean, Manhattan, cosine, chebyshev among other distance metrics in my k-means algorithm to calculate distances between the data points and the centers. In what situation would one distance metric be more useful over the other in a clustering scenario? [Comparing all the above mentioned distance metrics] | 1 |
Let I be an open interval that contains the point c and let f be a function that is defined on I except possibly at the point c. Suppose that lim |f(x)| as x->c exists. Give an example to show that lim f(x) as x->c may not exist. Not really sure of an example for this? | 1 |
I'm modeling the flight trajectory of a golf ball, and using angular velocity to calculate the Magnus force. Currently, I'm assuming angular velocity to be fixed throughout the ball's flight. How accurate will this be? How much will the angular velocity of the ball be affected by air resistance? | 1 |
I got really confused about the graph of the relationship between wavelength and intensity of black body radiation. What does the peak stand for? And what does the graph tell us? How can we analyze it? | 1 |
How would I go about computing the volume of an ellipsoid with spherical caps removed and a cylindrical hole through it? I'm thinking about finding dV of a cross section (the ellipsoid has a circular horizontal cross section). Would this be the best way to go? I need to find if the volume is dependent on the radius of the sphere. | 1 |
I'm looking for a proper English word to say "conversational partner". Is "interlocutor" a word an average person would understand? Are there any other words or shorter expressions which could describe a person you are having a conversation with, but who is not your friend and is basically unknown to you? | 1 |
Is there a polynomial time algorithm that gives the extreme point as output for which objective function is minimized/maximized ? I am not looking for any solution that minimizes/maximizes the objective function, but an extreme point of the feasible region for which objective function is minimized/maximized. | 1 |
I have read that in projectile motion both vertical and horizontal components are independent of each other but i don't get it that how it is possible i think that they are dependent. If they are not could someone explain with a mathematical relation. | 1 |
On a yoghurt advert, the voiceover claimed that you have infinite combinations with it. However, given that there is a finite amount of matter, is it possible to have infinite combinations with the yoghurt or just a very large number of combinations? | 1 |
In the Lagrangian path-integral formulation of QFT, an anomalous symmetry is defined to be a symmetry of the action which is not a symmetry of the measure of the path integral, and therefore not a symmetry of the partition function. How do we define an anomalous symmetry in the Hamiltonian formulation of QFT, where this is no path integral or partition function? | 1 |
Speaker A: We want to ask you some questions. If you don't mind, of course. Speaker B: [He opens the door of his house] Sure, be my guests. Is the idiom being used correctly? If not, what would be a better alternative? | 1 |
He missed out several important facts. He omitted several important facts. I think these two sentences are the same meaning. Is there a slight difference? A few days ago, an American native speaker explained to me that "omit" means intentionally take out whereas "miss out" means mistakenly take out. Is it true? Could anyone clarify the difference to me? | 1 |
There are several PR firms, lobbying groups who specialize in mud slinging, making wild allegations on behalf of their clients. Is there a word that describes such a person whose job is to make allegations against others? | 1 |
I looked all over but could not find anything. Is there a package out there that has a symbol/dingbat of a calculator? I know there probably isn't, but I've seen much stranger stuff out there before... | 1 |
Suppose there are two light beams. One is red while the other is violet. The energy of both is the same. Which one of these beams has a larger number of photons, or is the number of photons relevant? | 1 |
I am sure there has to be a more precise word to describe a person that is not giving up on her beliefs no matter what other says. You could say consistent in her beliefs, but I am looking for something more elaborate. An example of such a person might be Margaret Thatcher. Thanks | 1 |
What is the origin of the idiomatic expression rub someone the wrong way? Is it correct to use the idiom in reverse, i.e. rub someone the right way, possibly meaning to calm or to please? | 1 |
I know of at least three equivalent formulations of QM: The "normal/standard" one, dealing with Hilbert spaces and state vectors. The Feynman path-integral formulation. The Wigner-Weyl phase space formulation. My question is: what is the usual name given to the first, "normal" formulation that everyone learns as an undergraduate? | 1 |
I know the differences in the meaning of word "trash" and "garbage" but how about "take out the trash" vs. "take out the garbage"? Can both these expressions be used interchangeably? What is the difference in meaning if any? | 1 |
My textbook states that "Laser communication is much faster than microwave communication." But, how can that be? Both are electromagnetic waves with different frequencies but, how can the speed be different? Or Is the statement referring to any kind of processing speeds involved? | 1 |
I might be mistaken, but I feel odd calling the following "wooden handrails", since handrails are supposed to be made of metal. Is it OK to call it "handrail", "guard rail", or a "wooden handrail"? Or is there a better term for it? | 1 |
Today, my teacher proved to our class that every convergent sequence is a Cauchy sequence and said that the opposite is not true, i.e. Not every Cauchy sequence is a convergent sequence. However he didn't prove the second statement. Is there an example or a proof where Cauchy sequence is not convergent? | 1 |
Is there any good word/phrase/idiom for that feeling of scorn when you're accepted by someone/something after getting rejected the first time? I remember a phrase being quoted by Nathan Fillion in Castle when Richard Castle's daughter is rejected to Stanford and later gets in. Still can't remember the lines, just the situation. | 1 |
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