Should I delete the intercept
When is it ok to remove the intercept in a linear regression model?
PHP Echo Line Breaks How can I disable the volume warning if you raise the volume too much? How can I split a polygon by network line in QGIS? I have a road network as line layer and a land cover as polygon layer, I want to find number of subpolygon for each polygon that divided by line layer in QGIS?  I used union function in Geoprocessing Tools in Vector menu of QGIS and then polygonize function to convert union result to polygon but in table of new polygon there is NULL data. "every" vs "each"? Is there a way to unfold a mesh? Is there a way to take a mesh, cut it with seams or sharp edges and flatten it, so that the faces stay the same shape and size?  Making paper models is one aspect, where you could use that technique.  No, I'm afraid SZ0Return is not going to do it properly.  And misusing the UV-unwrap is only a last option.    Note, while it's an option to revert to Blender 2.49 which had a script to do this, I'd like a solution that I can use inside the current workspace. Currently look after 3 websites. I changed one of them to be HTTPS as it's ecommerce, however have seen a huge drop in organic traffic since this was implemented. Went from around 800 impressions to 400.   Any ideas as to why?   Very concerning as I expected it to improve if anything!  I set up 301 redirects to carry through to old pages to http://www.example.com/product1 would go to https://www.example.com/product1  I also set up a separate webmaster account for the HTTPs version as our integration wasn't working well with Google Merchant Centre, and data is flowing correctly but unsure why/if this would cause conflict.  Very confused! Why does `\texttt` repeat and shrink my equation? When I use \texttt with the caret symbol in an amsmath equation environment, I get a very weird result. Specifically, the text repeats itself four times while shrinking.  MWE:  \documentclass{article} \usepackage{amsmath}  \begin{document}  \begin{equation*}     \texttt{y^o} \end{equation*}  \end{document}   Compiling this document with pdflatex produces the following result:    The same result occurs even if I remove the o character. To fix it I could modify the offending line to \texttt{y$^o$}, but why is this repeating happening in the first place? What is so special about $\alpha=-1$ in the integral of $x^\alpha$? Of course, it is easy to see, that the integral (or the antiderivative) of $f(x) = 1/x$ is $\log(|x|)$ and of course for $\alpha\neq - 1$ the antiderivative of $f(x) = x^\alpha$ is $x^{\alpha+1}/(\alpha+1)$.  I was wondering if there is an intuitive (probably geometric) explanation why the case $\alpha=-1$ is so different and why the logarithm appears?  Some answers which I thought of but which are not convincing:   Taking the limit $\alpha=-1$ either from above or below lead to diverging functions. Some speciality of the case $\alpha=-1$ are that both asymptotes are non-integrable. However, the antidrivative is a local thing, and hence, shouldn't care about the behavior at infinity. The Tree of Life in Evangelion I've noticed references to the Kabbalah in a couple of anime I've watched.  One of them is Neon Genesis Evangelion.  Neon Genesis Evangelion has it in the sky in both the opening credits and in the series itself:     I also remember it was on the ceiling at NERV, but the best screencap I could find of that was too tiny to be visible.  So, my question is, Is there any deeper meaning to the use of the Kabbalistic tree of life, or is it just used because it looks cool? Is a contradiction enough to prove a set equality to $\varnothing$? I need to find the cardinality of the set $S$ of all infinite subsets of $\mathbb{Q}$.   It's easy to prove $\operatorname{card} S=\mathfrak c$ if you first prove that the cardinality of the set of all finite subsets of $\mathbb{Q}$ is $\aleph_0$.   But is there some other proof for the statement without using the second one (about finite subsets)? Probably there is =) Does GCM (or GHASH) only provide 64-bit security against forgeries? In a  a doubt was voiced about my answer, which claims GCM to requires $2^{128}$ for a successful forgery. The doubt was that the square root needs to be taken meaning the security would be $2^{64}$.  So of course I immediately checked the relevant security theorem ():  $$\mathbf{Adv}^{\text{auth}}_{\operatorname{GCM}[\operatorname{Perm}(n),\tau]}(\mathcal A)\leq \frac{0.5(\sigma+q+q'+1)^2}{2^n}+\frac{q'(\ell_A+1)}{2^\tau}$$  with $\sigma$ being the total plaintext size in blocks, $q$ being the total number of encryption queries, $q'$ being the total number of decryption queries, $n$ being the size in bits of the underlying permutation, $\ell_A$ being maximum authenticated input length in blocks and $\tau$ being the tag size in bits.  Now clearly from this we can see that performing $2^{n/2}=2^{64}$ queries yields a strong enough advantage for a break.  Now my question is: When talking about "n-bits of security" or "needs $2^n$ operations to break", do we usually talk about "online" security, ie queries to an oracle can be done and cost $1$ or "offline" security where no oracles are available or do we need to make this decision depending on the situation?  TL;DR: Does GCM offer 64 or 128 bit security? I have lost my passport here in Beograd. Can I travel just with my Czech ID card from Belgrade to Budapest? I have read a lot about the SB-800/SB-900 but I am on a low budget (around ~120$). Is there an external flash that I can have to start learning to use it? I do not need TTL compatibility so it can be an older model. I have a Nikon D5000. Is there a Google Drive client available? I'd like to install a  client for Xubuntu (12.04).  I'm getting non-English Google results, and I didn't find  in the Xubuntu repositories.   Does anyone know of a client that works well for Ubuntu or it's supported derivates (or installation instructions for grive?) R raster: masking a raster by polygon also remove cells partially covered? I want to mask out a raster based on the values of a polygon: i.e., set to NA all values of the raster that are not covered by the polygons. However, it seems that raster::mask() masks out cells (i.e. set them to NA) even if they are partially covered?  This is similar to the question: , but unlike crop(), mask() does not have the snap="out" option.   Check: here the right point of the triangle touches a cell, yet that cells is masked out.   library(raster) library(sp)  r &lt;- raster(xmn=1, xmx=5, ymn=1, ymx=5, nrows=4, ncols=4) r[] &lt;- 1:length(r)  Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2))) Sr2 = Polygon(cbind(c(4.1,4,2),c(2,3,2)))  SpP = SpatialPolygons(list(Polygons(list(Sr1), "s1"), Polygons(list(Sr2), "s2")), 1:2)  plot(mask(r, SpP)) plot(SpP,  add=TRUE) Is there a unique solution for this quadratic matrix equation? Prevent VLC from starting a new instance every time a media file is opened How do you read CSS rule values with JavaScript? What really causes light/photons to appear slower in media? I know that if we solve the Maxwell equation, we will end up with the phase velocity of light being related to the permeability and the permittivity of the material. But this is not what I'm interested in - I want to go deeper than that. We know that the real speed of light is actually not changing, the decrease in speed is just apparent. Material is mostly empty, the light will still travel with $c$ in the spacing. The rare atoms will disturb the light in some way. So I am interested in how the atoms affect the light. Photon absorption-emission theory Some textbooks that I read explain it in a way kind of like this: In a material the photons are absorbed by atom and then re-emitted a short time later, then they travel a short distance to the next atom and get absorbed&amp;emitted again and so on. How quickly the atoms in a material can absorb and re-emit the photon and how dense the atoms decides the apparent speed of light in that material. So the light appears slower because it has a smaller “drift speed”. Interference theory But recently I realize an alternative explanation: Atoms respond to the light by radiating electromagnetic wave. This “new light” interferes with the “old light” in some way that results in delayed light (advanced in phase), this can easily be shown by using simple phasor diagram. Consequently effectively the light covers a smaller phase each second, which gives the impression of a lower phase velocity. However the group velocity is changing in a complicated way. I think that the first explanation does not explain the change in phase velocity of light. if we consider light travelling into a slab of negative refractive index non-dispersive material, let’s say the light is directed perpendicular to the slab. The phase velocity’s direction will be flipped, but group velocity’s direction in the material will not change. Only the second explanation can explain the flipped phase velocity direction. I guess that the velocity that we get in the first explanation is actually belongs to the group velocity. It makes sense to me that the front most of the photon stream determines the first information that the light delivers. So the question is What really cause the phase velocity of light to be decreased?  &quot;drift velocity&quot; of photons (they aren't the same photons, they are re-emitted all the time) phase difference between absorbed and emitted light something else  And also, I still don't really understand detailed explanation of the absorption-emission process for small light's wavelength (for large lambda compare to the atoms spacing, the photons will be absorbed by the phonons). The dispersion relation that we know is continuous and also some material is non-dispersive, therefore the absorption process must occur in all frequency for a certain range. So definitely it doesn't involve the atomic transition, otherwise it will be quantized. My guess is that the relevant absorption process gets smooth out by the dipole moment. What makes the spectrum continuous? EDIT: link for dispersion relation: