Is there a declaration/assign function in MATLAB or Python which works in both ways, bilateral/mirror type of use? Example;  x = 3 print x #output is 3#   but what if there is a type of function, like this;  x _=_ 3 print x # output is 3 # print 3 # output is x #
I was working with a new C++ developer a while back when he asked the question: "Why can't variable names start with numbers?"  I couldn't come up with an answer except that some numbers can have text in them (123456L, 123456U) and that wouldn't be possible if the compilers were thinking everything with some amount of alpha characters was a variable name.  Was that the right answer?  Are there any more reasons?  string 2BeOrNot2Be = "that is the question"; // Why won't this compile?
Set the default permission when creating a file K-Means clustering for mixed numeric and categorical data My data set contains a number of numeric attributes and one categorical. Say, NumericAttr1, NumericAttr2, ..., NumericAttrN, CategoricalAttr, where CategoricalAttr takes one of three possible values: CategoricalAttrValue1, CategoricalAttrValue2 or CategoricalAttrValue3. I'm using default . It works with numeric data only. So my question: is it correct to split the categorical attribute CategoricalAttr into three numeric (binary) variables, like IsCategoricalAttrValue1, IsCategoricalAttrValue2, IsCategoricalAttrValue3 ? How to create an annuity timeline on LaTeX I was wondering, how can I create a timeline exactly like this one:    on LaTeX?  I am a Finance student, and write all of my notes using LaTeX. These timelines, are giving me a headache. Since we use a lot of different timelines because of annuities. I want to learn how to create one basic timeline, so that I can then change anything I want. But basically, I want something like this, with the arrows and everything.  Thank you so much guys! Prove $-(-a)=a$ using only ordered field axioms I need to prove for all real numbers $a$, $-(-a) = a$ using only the following properties:     I tried by starting with P12 written using symbolic logic:  $\begin{align} \forall a,b \in P \to &amp; a \cdot b \in P \Leftrightarrow True \\ \forall a \in P \land \forall b \in P \to &amp; a \cdot b \in P \Leftrightarrow True \\ \lnot \left[ \left( \forall a \in P \right) \land \left( \forall b \in P \right) \right] \lor &amp; a \cdot b \in P \Leftrightarrow True \\ \exists a \notin P \lor \exists b \notin P \lor &amp; a \cdot b \in P \Leftrightarrow True \\ \end{align} \\ $  and played with evaluating it with $b = -1$, $-a$ and so on. But, felt this wasn't really a solution because the last symbolic logic statement above is ambiguous.  Not to mention--other than P12--I haven't used any of the axioms listed above whatsoever. ( And I've not bothered to prove any of the theorems of symbolic logic I have used. )  Can anyone give me a start on this problem?  Many thanks in advance.  Edit  Thank you, everyone! .  Best regards! What are the integer solutions to $a^{b^2} = b^a$ with $a, b \ge 2$ I saw this in quora.  What are all the integer solutions to $a^{b^2} = b^a$ with $a, b \ge 2$?  Solutions I have found so far:  $a = 2^4 = 16, b = 2, a^{b^2}  = 2^{4\cdot 4} =2^{16}, b^a = 2^{16} $.  $a = 3^3, b = 3, a^{b^2} = 3^{3\cdot 9} =3^{27}, b^a = 3^{3^3} =3^{27} $.  In the general case, $a$ and $b$ have the same set of prime divisors, so let $a =\prod_P p_i^{a_i}$, $b =\prod_P p_i^{b_i} $ with each $a_i \ge 1, b_i \ge 1$.  $b^a =b^{\prod p_i^{a_i}} =(\prod p_j^{b_j})^{\prod p_i^{a_i}} =\prod p_j^{b_j\prod p_i^{a_i}} $  $a^{b^2} =a^{\prod p_i^{2b_i}} =(\prod p_j^{a_j})^{\prod p_i^{2b_i}} =\prod p_j^{a_j\prod p_i^{2b_i}} $  Therefore, for each $p_j$, $b_j\prod p_i^{a_i} =a_j\prod p_i^{2b_i} $.  I haven't gotten any further than this.  I conjecture that there are no other solutions. Showing that $1^k+2^k + \dots + n^k$ is divisible by $n(n+1)\over 2$ Where can I get a device with 'Ubuntu for phones' pre-installed? Why does $\sqrt{n\sqrt{n\sqrt{n \ldots}}} = n$? Ok, so I've been playing around with radical graphs and such lately, and I discovered that if the   nth x = √(1st x √ 2nd x ... √nth x);   Then  $$\text{the "infinith" } x = x$$  Example:   $$\sqrt{4\sqrt{4\sqrt{4\sqrt{4\ldots}}}}=4$$ Try it yourself, type calc in Google search, hit  then a number, such as $4$, and repeat, ending with $4$, (or press the buttons instead).  I'm a math-head, not big enough though, I think this sequence is divergent or convergent or whatever, too lazy to search up the difference.  However, can this be explained to me? Like how the Pythagorean Theorem can be explained visually. When I was a kid we had a VHS tape of some Disney live action (not animated) sci-fi movie. It may have been a mini-series or a made-for-tv movie, but I'm not sure. I'm also not sure about the year but it would probably have been late 80s or early 90s based on when I would have seen it. I know it was Disney because they had some live action Goofy and Mickey running around the movie's set as an introduction discussing the plot with a host before the movie.  The plot is basically as follows:   A starship is loaded with mostly children and teenagers as a cross-galaxy human settling effort. Accidents (which are not really accidents and later revealed) cause adult crew members to be killed.  They travel to another planet and face all sorts of troubles. It arrives at the new planet after overcoming obstacles.   Other memorable scenes that may help:   Navigating out of earth's asteroid belt made out of space junk. One of the adults was killed via an airlock malfunction. The ship was supposed to be peaceful with no weapons. At one point they bring on board some crazy guy who puts together a rail gun. There's a memorable line like "Do you want no weapons at all or a well aimed rock?"  There's a planet or space station (I can't remember which) that has a fight scene with the evil bad guy. This scene takes place on what looks to be a carnival or fairground. The bad guys are trying to steal the ship the kids are on because it has some kind of really good futuristic space drive.   Hopefully you remember it better than I do! I've tried looking online for it before with no luck. Is there a function to round a float in C or do I need to write my own? Check for missing fonts/characters in XeLaTeX? Because I began to use many Unicode characters (Japanese, some unusual diacritics, etc.) I switched from LaTeX to XeLaTeX to render my documents. Unfortunately, if a font is missing, the letters are simply left out (for example, when I had forgotten to specify the font for Japanese) without any error (and I can't seem to spot a warning either). I will read the result, but I prefer to get some early warning if some character isn't available. Is there any way to get a warning about characters that have not been rendered? An error would be even better. I came across the :    Which states:     $\pi$ Pi      Pi is an infinite, nonrepeating $($sic$)$ decimal - meaning that   every possible number combination exists somewhere in pi.  Converted   into ASCII text, somewhere in that infinite string of digits is the   name of every person you will ever love, the date, time and manner    of your death, and the answers to all the great questions of    the universe.   Is this true? Does it make any sense ? Using global variables in a function Health effect of electromagnetic and acoustic waves on brain function Selling customized versions of Ubuntu My question is next: "Can I modify some version of Ubuntu Linux, add some software related to electrical engineering, modify look and some functions of Ubuntu, basically customize the entire system so it suits the needs of electrical engineers working on the field or in the office, and then that customized system sell in order to make profit?"   I'm not sure am I allowed to do that (is it legal?), so I would appreciate answer. Find a value anywhere in a database I have a manuscript that is under review in a major journal which is a main result out of a few recent years of my research. When applying for faculty positions, I would like to send the draft as a part of my writing sample. But since the material is not yet published, I am not sure if it is a good idea.  What are the foreseeable disadvantages of sending an article in review to the faculty search committee?  My area is neuroscience / biomedical engineering.  Update: The paper got into a high-profile journal, and I got a job at a different place which did not require a writing sample. Weird font in system windows Suddenly all the system windows have this weird font. I can't read nor understand what the system is asking me. How can I change it to normal fonts?    I'm using OS X Yosemite 10.10.3 Entropy increases when two substances mix with each other.  For example, the entropy of mixing of two different gases are given by $$\Delta S= 2Nk\ln\frac{V_f}{V_i}\;.$$  But, the entropy doesn't increase when the two gases mixing are same.  This is pointed by Daniel V Schroeder:     It's important to note that this result applies only if the two gases are different like helium and argon. If you start with the same gas on both sides, the entropy doesn't increase at all when you remove the partition.   Now, why is this so? Both the gases, though the same, increase their individual entropies when they expand, don't they?  So, why did Schroeder say there is no entropy of mixing? What actually happens such that there is no change in entropy when the gases are the same? Unexpected gaps in IDENTITY column