Perfect infinitive for future
Perfect infinitive
Give users a way to see their "Positive Question Record" score Why we don't use gamma rays, x-rays or ultraviolet to transmit data? The greater the frequency range of a transmission medium, the greater the number of bits per second it can transmit. In other words, the bigger the bandwidth in hertz available, the bigger the bandwidth in bits per second that can be transmitted.  Given that, why we don't use gamma rays, x-rays or ultraviolet to transmit data instead of e.g. visible(light) in optical fiber or microwaves(cell phones)? Given three matrices $A$, $B$ and $C$ such that $ABA^T C$ is a square matrix, the derivative of the trace with respect to $A$ is:  $$ \nabla_A \operatorname{trace}( ABA^{T}C )  = CAB + C^T AB^T $$  There is a proof . However, I was not able to understand the second line of the proof. it says something like this:  $$ \nabla_A \operatorname{trace}( ABA^T C )= \nabla_\bullet \operatorname{trace}(f(\bullet)A^{T}C) + \nabla_\bullet \operatorname{trace}(f(A) \bullet^T C) $$  Where  $f(A) = AB$  I tried searching the proof or any hint using google, but I couldn't fine anything. Could anyone please help me with this second line. I cannot sleep. I am obsessed with this proof. Nonlinear regression model linear in some parameters In a set of  that I stumbled upon online, the author discusses a nonlinear regression model, which is linear in some parameters, like this $$ y = \theta_1 + \theta_2\exp \left( {\theta_3x} \right) + \varepsilon $$ and suggests to first perform a nonlinear regression to estimate $\theta_3$, and then use OLS to estimate the other two parameters. I am not very experienced in regression modeling, so please forgive me if I ask a very simple question, but I don't understand how you can do this consistently without also estimating the other 2 parameters? Apparently, there is some trick involved, which I don't understand...  Another question is what happens to the ability to do inferences based on parameter estimates to the complete model if you do the regression in two stages like that?  Many thanks! How do I install PowerShell? Not long ago I read something on Microsoft's website about PowerShell being available for Ubuntu.   How would I go about the install of PowerShell?  I'd appreciate guidance for both Xenial &amp; Trusty.   Any installation method is fine, whether compiling source or relying on a package-manager.  Source-compiling methods should contain beginner-level detail. Short circuit or disconnect to bypass a compressor Buffering GeoJSON file using Python? I'm trying to perform a simple buffer on GeoJSON file using Python script. I am able to do it on a shapefile using Python script and on GeoJSON using QGIS fix distance buffer tool but I can't figure out how to do it on GeoJSON using Python script. I read many posts on it but none of them include working solely on GeoJSON. I also know that it is possible to convert GeoJSON to .shp but I need to work only with GeoJSON files.  My code that works for .shp file:  from osgeo import ogr  ds = ogr.Open(r'C:\vector files\tryyy.shp', 1) in_lyr = ds.GetLayer() out_lyr = ds.CreateLayer('new_buff44',in_lyr.GetSpatialRef(),ogr.wkbPolygon) out_lyr.CreateFields(in_lyr.schema) out_defn = out_lyr.GetLayerDefn() out_feat = ogr.Feature(out_defn) bufferDist = -0.00015075  for in_feat in in_lyr:      geom = in_feat.geometry()     out_feat.SetGeometry(geom)     for in_feat in in_lyr:          geom = in_feat.geometry().Buffer(bufferDist)         out_feat.SetGeometry(geom)         for i in range(in_feat.GetFieldCount()):             value = in_feat.GetField(i)             out_feat.SetField(i, value)         out_lyr.CreateFeature(out_feat)  del ds print "finish"   When I change the file from shp to geojson in the org.Open line I get:      NoneType' object has no attribute 'CreateFields'   I thought that if I read vector file as OGR datasource object then it doesn't matter which format is the original vector file.   Can someone help me understand what I should change so that the code will work on GeoJSON files? How can you detect if users have created sock puppet accounts? How many users have created more than one profile on SO to vote themselves on their other original profile? There are some benefits when you have more reputation and sometimes you don't want a single -1 vote on your question or answer. In this case you may have an extra account to convert that -1 vote into 0 vote and  upvote for each of your questions and answers to gain reputation. I think it is not a good thing to do as a good developer.  Is there any way to recognize this situation? I think there should be some stats in each user's profile about how many votes are posted by each user on him/her or something like that.  So how many users have more than one profile? How to handle this situation? I have not created one yet but............ I don't think so :) How to change boot priority? I have a laptop with Ubuntu installed as the only OS. I also have a USB stick with a Windows 7 installation on it. I want to install Windows from the USB stick on my laptop but when I try to restart the laptop to get access to BIOS, I can't seem to find the command for it, its like it skips everything and just says Ubuntu and then takes me to the login screen.  How do I change the boot priority to USB in Ubuntu? Can we have a notification when the answer to any of my question got edited? If a user asked a question and got an answer which was not helpful.  After sometime the answerer edits the answer with some good content. How the OP will get to know that?  Is it necessary to add comment check my edited answer?  We can say that the OP should refresh the page to find the helpful answer.  Consider if the OP finds the answer as helpful and accepted that. After sometime if the answerer/anyother user edit the answer to change the content which may not solve the issue.   How will it be notified to OP?  currently we are notifying the OP when there is any comment to the queation or any new answers or any comments with the name of OP with @ to any answer.  This will lead the future visitors to confuse and reduce the quality of post.  Can we have a notification to the original poster when the answer to any of his/her question got edited? How do I enable comments for user profiles? With users being entities in D7 I assumed the user type would would have built in "comment" option. That doesn't seem to be the case. I just want to allow users to leave comments on the user profile page. Is there a simple way to doing that? I would like to see everything on my computer screen in grayscale (like say the kindle screen). How do I do this? Google Maps API map doesn't appear Proving that $\lim\limits_{x\to\infty}f'(x) = 0$ when $\lim\limits_{x\to\infty}f(x)$ and $\lim\limits_{x\to\infty}f'(x)$ exist How can I add a folder to the launcher for quick access to it. In this particular case I wish to drag it to the launcher. Which repository source do I need to add to my sources.list to access the package firmware-linux-nonfree?  I am using Deb 6 testing 32 bit. What is the difference between a linear and a circular polarizer? Change MySQL default character set to UTF-8 in my.cnf? if $x_i$ are IID  continuous random variables, with $E[x_i]=μ$, is the following correct?   $E\left[\prod_{i=1}^n(1+⍺\space x_i)^i\right] = \prod_{i=1}^nE\left[(1+⍺\space x_i)^i\right] =  \prod_{i=1}^n(1+⍺\space E\left[x_i\right])^i = (1+⍺\space μ)^n$  thanks! Proving that without the axiom of choice there is a set with an accumulation point that isn'tthe limit of a convergeant sequence I've been reading the simple parts of Thomas Jech's book on the Axiom of Choice and came across the following proof on page 141. The proof assumes a mathematical model without the axiom of choice.     Lemma. $X$ is D-finite if and only if $X$ does not have a countable subset.       Theorem. There is a set $S$ of real numbers and a real number $a \not \in S$ such that a is in the closure of $S$ but there is no sequence $(x_n)^{\infty}_{n=0} \subset S$ such that $(x_n)^{\infty}_{n=0} \longrightarrow a$.       Proof. Let $D$ be a D-finite infinite set of reals. We claim that the set $D$ must have an accumulation point. To prove this claim suppose that all $d \in D$ are not accumulation points, then let $\{I_n:n=0,1,...\}$ be a fixed enumeration of open intervals with rational endpoints. Assign the least $n$ such that $I_n \cap D={d}$ to each $d \in D$. This makes $D$ countable and by the above lemma gives us our contradiction. So $D$ has an accumulation point $a$. Let $S=D \setminus\{a\}$ and since $S$ is D-finite, every convergent sequence in $S$ is eventually constant.   Could somebody explain this proof? Why is the last sentence true/ Why does this mean every convergent sequence is eventually constant?  I think the following theorem is important     Theorem. There is a model of ZF which has an infinite set of real numbers without a countable subset