I am experiencing difficulties understanding the concept of convolution and especially convolution of 2 independent indicator functions. I would be really thankful if someone can help understand the intuition behind it. Thank you in advance
I've been wondering about this one for a while; I find it a little weird how abruptly it happens. Basically, why do we need just three uniforms for $Z_n$ to smooth out like it does? And why does the smoothing-out happen so relatively quickly?  $Z_2$:     $Z_3$:    (images shamelessly stolen from John D. Cook's blog: )  Why doesn't it take, say, four uniforms? Or five? Or...?
Antonym of "phobia" If a phobia is to have an irrational fear of something, what is the word for having an irrational affinity for something?  For example a numerologist may fear the number 13, but be attracted to (or even have a love for) the number 8. (Some would say this is irrational.) What's the batched Refactor Fields tool "field mapping" syntax in QGIS? In QGIS, there is this nice tool "Refactor Fields" in the Processing Toolbox :    Using it on a single layer is fairly straightforward.  However, when you plan on using it in a batch mode, one can see the "Fields mapping" textbox. I'm looking for an example of the syntax to be used there.  I haven't found any specific documentation yet. What makes a bread either close or open crumbed/textured? What causes the texture of bread to be open, ie with lots of large holes, or close, ie a regular, uniform tender crumb with no large holes? How can I achieve either? Upgrading straight handlebars to drop handlebars I have a two-and-a-half year old  (with a road-bike-like frame and thin tires; it's somewhere in the loosely-defined "hybrid" range) that I use to commute to work, twenty-five miles round-trip, once or twice a week. The bike has straight handlebars, and having gotten used to the idea of commuting via bike, I'm interested in upgrading to drop handlebars. It looks like I'd need new break/shift levers to go with the handlebars; the whole upgrade looks like it'd run a couple hundred dollars. This is a sizable fraction of the original cost of the bike, which leads me to wonder if I'm better off saving my money for a new bike that's a little better adapted to my use.  Is upgrading my bike's handlebars a reasonable investment? What is the "canary thread" and why is it starving? The following occasionally appears in /var/log/syslog:  rtkit-daemon[1145]: The canary thread is apparently starving. Taking action. rtkit-daemon[1145]: Demoting known real-time threads. rtkit-daemon[1145]: Successfully demoted thread 1431 of process 1368 (n/a). rtkit-daemon[1145]: Successfully demoted thread 1430 of process 1368 (n/a). rtkit-daemon[1145]: Successfully demoted thread 1368 of process 1368 (n/a). rtkit-daemon[1145]: Demoted 3 threads.   What's going on here? Why this proof $0=1$ is wrong?(breakfast joke) We have $$e^{2\pi i n}=1$$  So we have $$e^{2\pi in+1}=e$$  which implies $$(e^{2\pi in+1})^{2\pi in+1}=e^{2\pi in+1}=e$$ Thus we have $$e^{-4\pi^{2}n^{2}+4\pi in+1}=e$$  This implies $$e^{-4\pi^{2}n^{2}}=1$$  Taking the limit when $n\rightarrow \infty$ gives $0=1$. What is wrong with defining \bal as \begin{align}? I'm using Microsoft Word 2010 and I worked in a word-2003 compatible document (.doc). After hours of working, I selected a half of text and did Ctrl+X to copy it into another document. Surprising, after closing the current document and opening a new one and pressing Ctrl+V, nothing happened. After closing original document, ms word asked me if I want to save the clipboard buffer and I pressed No, as I didn't knew that MS Word has it's own clipboard.  Is there a way to recover that text that was "cutten" from original document and never "pasted" to the new one? The PC was not rebooted so i guess all my temp files are here. How do I convince gdal2tiles to output pngs with transparency? Friendly_Id and Reserved Words -- How can i replace the reserved word? Why are two permutations conjugate iff they have the same cycle structure? Why Does The Background Image Not Show in Orthographic View? Chi-squared test when two vectors have different lengths I want to compare two groups (vectors) having different lengths to see if their distributions differ considerably. However, when I use chisq.test, I get an error due to inequalities of lengths:  &gt; chisq.test(factor(Group1), factor(Group2))   results in:  Error in chisq.test(factor(Group1[, col]), factor(Group2[, col])) :  'x' and 'y' must have the same length   Could someone help me with this? Thanks. Lubuntu 16.10: How to make login through greeter without typing password work I would like to simulate the behaviour of a zener diode in LTspice. Consider the following schematic         &ndash; Schematic created using   I'm interested in simulating its performance when Vcc changes from the rated value (say 12V), for example when Vcc varies from 11 to 15 V.  Now, I know how to simulate this behaviour in LTspice for a generic diode or even for a particular diode which is available in the model library, but when it comes to using a custom diode, I have no idea on how to specify the diode parameters.  Looking into the documentation I was able to come up with a setup that is the correct one, that is, I can specify a custom diode model but now I'm having problems in understanding where to find all the parameters since the datasheet of my diode of choice does not provide all of them. In the LTspice model shown below I've picked a 4.7 V zener diode that was available just to have a base model to edit (and a 1k resistor just for reference).    The diode I'd like to use is a 3V . How can I simulate, as realistically as possible, the behaviour of this diode given the few parameters available in the datasheet? JDBC-ODBC Bridge queries to Access fail when they have accented characters I am running Wireshark on my linux machine and i have simple python web server running on localhost:8080  I am capturing only local port 8080. When i open browser on localhost:8080 wireshark captures huge amount of tcp communication (as page loads with all resources) but there`s no HTTP only TCP...   Why i cannot capture HTTP on custom port ? I unplugged my USB stick from Ubuntu 16.04 without the save remove option, but exfat should be fine doing so. No read write was happening, the partition does not use journaling. What I end up with is an unmountable USB stick with checksum error.   What tools are there to recover the partition table or at least the data on the USB stick? What I am doing now is scanning via parted. Has anyone experienced the same problem with exfat and recovery options? Unfortunately parted probably won't detect the partition because .  I also tried to use Partition Wizard on Windows but it failed to detect anything, just showing unallocated space. How do I proceed? are there helpful tools under Windows or Ubuntu?    I also tried to use gpart -v /dev/sdb but it failed to detect anything. On OS X there is a tool called fsck_exfat, is there any on Windows?  update The disk is preinstalled with Parted Magic. After quick search no partition shows up. This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application? How can I solve this quantum mechanical "paradox"?