I have a point feature class in a geodatabase that uses WGS84 as its SRS. A colleage of mine created points in this feature class using an external database containing lat and long values. However, the lat and long values in the external database were using NAD83 (my fault -- I knew they were, I just forgot). I thought it wouldn't be a problem -- I just created a copy of the geodatabase and changed the coordinate system used by the feature class to NAD83. Should be good, right?  I added this feature class into ArcMap. I saw that the points in the copied feature class (now using NAD83) exactly line up with the original feature class (using WGS84). That doesn't seem right. If two points, having the same lat / long values, but referenced in different coordinate systems are overlaid on the same map, one of them should be projected on the fly to the coordinate system of the data frame, no?  Now, here's the weird part -- if I project the original point feature class (using WGS84) to NAD83, and add it to the map, then the points don't line up. See, this isn't what i expected, either. I expected that they would be projected to the other coordinate system (i.e., their lat / long values would be different by virtue of being projected, but they would be aligned with the original point because they were simply projected to the new coordinate system (then projected on the fly back to the original coordinate system).  Can anyone explain the behaviour that I'm seeing? And, how do I properly ensure that the NAD83 lat and long values collected by my colleague are projected to WGS84 in my target geodatabase properly?
I put 4 different layers into my ArcMap document, but only one of them will show up on the map! I should be seeing the other 3 layers as well. When I do a Zoom to layer, I can see one layer, but I cannot figure out how to make the other 3 show up at once on top of each other.  Before I opened ArcMap, I used ArcCatalog where I right-clicked 3/4 of the shapefiles and  clicked Properties &rarr; Coordinate system &rarr; Import and then clicked on my Trees layer, which has the coordinate system I want the other 3 to have. But when I opened ArcMap the 4 layers did not overlap, nor could I move them above or below each other.
Why is the even root of a number always positive? Let $n \in \mathbb N$ be a natural number and $a \in \mathbb R$ be a real number. The $n$-th root of the number $a$ is defined as follows:  Case I: $n$ is an odd number. In this case the $n^{\text{th}}$ root of $a$ is defined to be that number $b \in \mathbb R$ such that $b^n = a$.  Case II: $n$ is an even number. In this case the $n^{\text{th}}$ root of $a$ is defined to be that number $b \geq 0$ such that $b^n = a$.  Why is it that when $n$ is even, we only consider $b \geq 0$. For example, both $+2$ and $-2$ squared equal $4$, but when we say the square root of $4$ is $2$. Is there a reason for this? How can I run ssh-add automatically, without a password prompt? Code after bullet list isn't rendered correctly Possible Duplicate:         If there is a list immediately followed by a code block the code block is not recognized as code (Even though there is a newline between the two).  int answer = 42;  Note: This happens both in the WMD preview and in the final (server rendered) post. triggered my curiosity for this question. Why most of manga are black and white? Is this because of more cost if they add colors to it? Which of these sentences is correct?     Rupees are interchangeable with dollars   or      Rupees is interchangeable with dollars. Apache 2.4 - 403 HTTP status code How do I pre-populate a jQuery Datepicker textbox with today's date? I have a very simple jQuery Datepicker calendar:  $(document).ready(function(){     $("#date_pretty").datepicker({      }); });   and of course in the HTML...  &lt;input type="text" size="10" value="" id="date_pretty"/&gt;   Today's date is nicely highlighted for the user when they bring up the calendar, but how do I get jQuery to pre-populate the textbox itself with today's date on page load, without the user doing anything?  99% of the time, the today's date default will be what they want. Toast message with Chinese characters, is it a virus? I recently received some updates today from the Play Store. Every so often a pop notification, one of those bubble ones at the bottom of the screen with Chinese characters.  The most recent update I've noticed is the ES File Explorer. I wouldn't mind, but my device is rooted and so I am at risk. I have a screenshot of the notification.  My device is the Samsung Galaxy Tab A 9.7 and I have stock ROM installed.    What my question(s) are: Do I have a virus (it's not being picked up by Avast) and if I do, how do I remove it? Is there a way in javascript to detect if the unload event is caused via a refresh, the back button, or closing the browser? I am currently looking at the "unload" event of a window to try to determine how the "unload" event was triggered, but am having little success. Is there a way to determine how the javascript event was triggered?   Page Refresh Back Button (or navigate away from the page) Closing the Browser   Essentially I need to execute some code only when the browser window is being closed, not refreshed or navigated away from.  Purpose: When a customer does an update of our software, the update will redirect their first Internet request to an offer page. There is a button for a "Do Not Bother" option, but some users will simply close their browser. Upon closing the browser, I need to duplicate the "Do Not Bother" functionality so the user no longer gets redirected to the offer page. Simply attaching to the "unload" event will not work due to the different ways of leaving a page. Does the 2020 Apple M1 MacBook Pro support 2x daisy chained Thunderbolt Displays? The Apple Silicon based  supports Thunderbolt version 3 and I'm wondering if anyone has tried connection one to an ? Of course you'd need to use one of Apple's Thunderbolt 3 to Thunderbolt 2 converters. I also understand that this version is limited to supporting only a single 4K or 6K display, but since the original Apple Thunderbolt Display is only 2K I’d want to try and daisy chain these. Can I run more than one external display from the Apple Silicon M1 CPU/GPU based MacBook Pro (or Air)? Run TTY script every time I open a GUI terminal When I log in to a TTY I get the following nice text:  Ubuntu 16.04.03 LTS Log-in: username Password: Last log-in date/time Welcome to Ubuntu 16.04.03 LTS   * Documentation:  * Management:  * Support:  9 packages to update 4 updates are security updates   I would like the last 2 lines repeated every time I open a GUI terminal for all users in the adm group (but will settle for having the entire thing displayed each and every time I open a GUI Terminal for all users)  I tried the obvious:  fab-root@fab-ux-predator:~ $ cd /etc/update-motd.d/ fab-root@fab-ux-predator:/etc/update-motd.d $ ./90-updates-available  fab-root@fab-ux-predator:/etc/update-motd.d $ cat /var/lib/update-notifier/updates-available cat: /var/lib/update-notifier/updates-available: Permission denied fab-root@fab-ux-predator:/etc/update-motd.d $   What am I missing?  P.S. Obviously I can chmod o+r the file, but how future-proof would that be? Is the Moonbeam spell amazing, or are we doing it wrong? The description of the moonbeam spell (PHB pg. 261) says:  When a creature enters the spell's area for the first time on a turn or starts its turn there, it is engulfed in ghostly flames that cause searing pain... On each of your turns after you cast this spell, you can use an action to move the beam 60 feet in any direction.  We read this to mean a creature takes damage from moonbeam when any of the following conditions are met:  It begins its turn inside the moonbeam It enters the moonbeam on its turn The creature finds itself inside the beam on another character's turn, no matter how it got there  The creature will not take damage in the following instances:  A creature moves from one part of the beam to another (obviously it had to take damage, but it won't take more damage) A creature is in the beam after having been inside the beam already on that turn.  Following these assumptions, our druid cast a moonbeam and did damage to two enemies, Bob and Frank. On their turn, they took damage again, killing Bob. Frank left the beam. On the druid's next turn, she moved the beam in a circular motion, not exceeding 60 total feet of movement, and in the process the beam came in contact with a dozen enemies and ended on Frank. All dozen enemies received damage, as they were inside the beam at some point during the turn. On Frank's next turn, he again took damage for the fourth time and died. On each of the druid's turns, she moved the moonbeam around like this until the fight ended (it did not exceed the time limit and she made all concentration checks). Is this a legitimate use of moonbeam? It seems awfully powerful for a level 2 spell. Meta-analysis of means and medians in R? I've been asked to review the literature for all studies that estimate the mean and median Blood Lead Level (BLL) in a certain country, and then perform a meta-analysis to come up with one overall value for the mean and median level.   Is such a thing typically done? I'm not interested in any "effect size," just a univariate measure.   I'd like to create a forest plot and do some of the standard tests of heterogeneity across studies. Is there a package and function in R that will allow me to do a meta-analysis of mean and median BLLs?  Just to clarify, this would be a separate meta-analysis for means, and a separate meta-analysis for medians. I added this to /etc/crontab on a few different linux &amp; freebsd systems:  # monthly reboot: 3rd Tuesday of every month 56 07 15-21 * 2 root /sbin/shutdown -r now   I want a reboot on the 3rd TUESDAY of every month.  However, all the systems rebooted on the 3rd Wednesday of this month (the 19th).  What am I doing wrong?  Update: Thanks to Ranon's answer below, looks like the below revision will work, can anyone confirm or is there an even better way of doing it?  # monthly reboot: 3rd Tuesday of every month 56 07 15-21 * * root test $(date +\%u) -eq 2 &amp;&amp; /sbin/shutdown -r now Is a strong background in maths a total requisite for ML? I'm starting to want to advance my own skillset and I've always been fascinated by machine learning. However, six years ago instead of pursuing this I decided to take a completely unrelated degree to computer science.   I have been developing software and applications for about 8-10 years now, so I have a good handle but I just can't seem to penetrate the maths side of machine learning/probabilities/statistics.   I start looking at learning material and on the first page it might include something which confuses me and immediately sets up a barrier in my learning.   Is a strong background in maths a total requisite for ML? Should I try and fill in the blanks of my maths before continuing with ML? Can self learning really work for just a developer without any hard computer science background?    Related question: It seems that we are . This is the speed of our galaxy relative to the cosmic microwave background. Where does this rest frame come from? Is this special in any way (i.e., an absolute frame)? EDIT: I think the more important question is &quot;where does the CMB rest frame come from?&quot;. Help me understand the proof for Bolzano-Weierstrass Theorem! I have read in a book that the limit of the ratio of consequent Fibonacci numbers is the golden ratio. However, it was just mentioned thus not justified. So, my question is how would you derive the following limit: $$\lim_{x\to\infty}{\frac{F_n}{F_{n+1}}}=?$$ Where $F_n$ is the nth Fibonacci number? Can I update an early Airport Time Capsule? Does Professor X have any responsibility for the state of the world? Throughout the course of Logan, it's obvious that Professor Xavier is having issues controlling his powers, and at the end of the movie, just before      X-24 kills him   he claims to "remember" what he did and expresses regret. We also hear about an incident in Westchester that killed several mutants, that sounds like Xavier may have been involved. Is Xaiver the reason there are no more mutants? Is that why he's sorry, because he knows he killed them all?