I have a question about the following derivative. Let us have $X\in\mathbb{R}^{m\times n}, z\in\mathbb{R}^{n}$ and I would like to find the derivative $$\frac{\partial (z^{T}X^{T}Xz)}{\partial z}. $$ Any idea? It gives me a hard time. Thank you.
It's stated that the gradient of:  $$\frac{1}{2}x^TAx - b^Tx +c$$  is   $$\frac{1}{2}A^Tx + \frac{1}{2}Ax - b$$  How do you grind out this equation? Or specifically, how do you get from $x^TAx$ to $A^Tx + Ax$?
A question about a primitive root mod $p=2^{2^k}+1$, where $p$ is prime. Forgive me for the unclear title. Some time ago, my HTC M8, which is rooted and runs on a  showed something weird. Firstly, in the Google Maps App a mysterious blue dot appeared, that captures the screen completely and makes it impossible to quit or use the application. It looks like this (I could make a screenshot)     When this happens in Maps, the only thing I can do is a hard restart with Power+Volume Up.  Since I have seen this occasionally in the camera app as well, I suspect it is not a bug of Maps itself. I know that the Venom ROM is not standard but maybe this is connected to some setting and anyone has seen this. Btw, the Venom ran smoothly for almost 3 years now.  Question: Has someone a clue what this could be and how I can get rid of it? Which stats / gear can get the best our of wasteland exploration? Trying to get the best out of wasteland exploration here! I get it that you'd obviously need a big gun for survival out there, but apart from that, I'm wondering which stats / gear can get the best out of exploration.    How would you choose who to send out exploring from your dwellers. Which stat is the most important to choose explorers? Strength or endurance maybe? Does it make much of a difference equipping combat outfits? If so, whats the most important stat to boost through outfits? I understand that clicking "shut down" from the menu that comes up on clicking the cogwheel triggers the following command to be executed:  dbus-send --system --print-reply --dest=org.freedesktop.Hal /org/freedesktop/Hal/devices/computer org.freedesktop.Hal.Device.SystemPowerManagement.Shutdown   However, when I execute this command on a terminal, I get the following error:  Error org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.Hal was not provided by any .service files   Is it because 14.04 uses some other service for shutting down, or am I doing something wrong?    Note: This question is in follow-up of: I left my cast iron pot on the gas stove, on high flame, and then forgot about it for 3 hours. It was empty and I was drying it before I oiled it to store it. After I discovered it and let it cool, I oiled it with a paper towel and all this rusty stuff came off and continues to come off. Is my pan ruined? What should I do? The product of $n$ consecutive integers is divisible by $n$ factorial How can we prove that the product of $n$ consecutive integers is divisible by $n$ factorial?     Note: In this  and the comments here the OP has clarified that he seeks a proof that "does not use the properties of binomial coefficients". Please post answers in said newer thread so that this incorrectly-posed question may be closed as a duplicate. Mail.app crashes constantly, even after deleting mail profile and cache I thought the new Apple font was called San Francisco, but I cannot find it in the font list of the Keynote.app for my Mac. Is it called another way or it is not available for Keynote?  I am currently using OS X El Capitan. Apache answer both HTTP and HTTPS on the same port Reprojecting LiDAR data with libLAS, error: "latitude or longitude exceeded limits"? Comments must be at least 15 characters long, which is supposed to make comments like &quot;...&quot; impossible to submit. This works fine, however, there is a way around this, by using comment replies, even &quot;fake&quot; ones e.g. &quot;@somelongname ...&quot;. Can the system strip the comment reply part (e.g. &quot;@somelongname&quot;) before performing the minimum characters check? Editing Subject in new Gmail For , the answer given on 7 Feb about how to edit the subject line in the new format of Gmail does not work for me.   There is no box on the left with a down arrow to options to reply, forward or edit subject in my version. There is a book on the right offering options to    Reply Reply to all Forward Filter message Print Delete Report spam Report phising Show original Message text garbled Translate message Mark answered    But, no option to edit subject Log of products to sum of logs Using a foreign driver's license in California when staying with a J-1 visa I'm planning to attend a Californian university as a visiting scholar (not paid by the university) on a J-1 visa, for a total of four weeks; a colleague of mine will do the same, but for 12 weeks. I've been told (personally, ie. no citable sources) that, if you're staying on a J-1, you're effectively a California resident for the time you're there, and, therefore, need a Californian driver's license.  I've read up on this and found  that states:     If you are a visitor in California over 18 and have a valid driver   license from your home state or country, you may drive in this state   without getting a California driver license as long as your home state   license remains valid.      If you become a California resident, you must get a California driver   license within 10 days. Residency is established by voting in a   California election, paying resident tuition, filing for a homeowner's   property tax exemption, or any other privilege or benefit not   ordinarily extended to nonresidents.   I'm not planning to vote in any elections, nor will I own a home there, but I'm not sure what would constitute "privileges or benefits not ordinarily extended to nonresidents".  Do we need to get driver's licenses in California, or can we use our foreign licenses? How about day trips to Arizona or Nevada?  Note: this seems to be related to , but my question is specifically about staying there on a J-1. Philosophy is the mother of all science Prologue Running google search:  at the time of this post yields about 114,000 results, and while this Quora post:  puts forth the question to determine the truth of the matter, it does not address the historical, etymological, and philosophical import of the matter. This PhilSE Post:  clearly addresses theory, but does not address the historical aspect. The related question in Researchgate post:  seems to not provide a substantial answer either. Inquiry What is the  context in which the statement 'Philosophy is the mother of all science' or related ones began to recognize as a  the  relationship between philosophy and the advent of modern science under thinkers like ? That is to say, what historical and social consequences were responsible for seeing  somehow superior as a theory to the ? Epilogue The question is intended to determine the metaphilosophical insights of philosophers. For example, if Karl Popper used the phrase or one similar, did he appeal to previous philosophers for insight on that same relationship? See Also How can I automatically forward Facebook messages to my email or phone? I can create email addresses that forward to other email addresses.  Likewise, can I automatically forward Facebook messages to either my email or phone? Incorrect plot using pgfplots (trigonometric functions like cos, sin and tan) Cascading Dropdown I am new to SharePoint 2013. What I need to figure out is based on the following situation. I have several school districts with multiple schools within the school district. I would like to create a cascading dropdown that 1st lists the districts and then will automatically populate a list of schools within a particular district when the district is selected. Can someone tell me if this is possible and if so what steps do I take to achieve it?    Thank you! I have seen people showing one slide progressively by pressing Enter. Could anyone tell me how to realize that in Beamer? In how many ways can we choose $r$ numbers from $\{1,2,3,...,n\}$,   In a way where we have no consecutive numbers in the set? (like $1,2$)