Why the slope will be infinitive if the tangent of curve is verticle ?  Suppose $x^2+2ax+y^2=0$ is a curve and its tangent is verticle to $x$-axis. From what basis we call the slope of this axis will be infinitive? Actually I searched a lot but didn't find any specific answer.  Thanks in advance
Find the slope of tangent line to the curve at the point $(1, \pi/2)$  the equation is  $$\sin(xy) = x$$  The right answer was = Slope is infinite   My answer was taking the derivative and I end up in this equation   $$ (1-y\cos(xy))/ x\cos(xy)  $$  I substitute with the points and the calculator showed an error, Does the error means infinite ?
Deriving Newton's Third Law from homogeneity of Space COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? I'm currently the proud owner of Frost the horse. What I want to know is, what will happen to him if I ride another horse?  Obviously nothing will happen as long as I have him in sight, e.g. I'll be able to ride Frost to make him my horse again.  Scenarios  But what will happen if, before I get back on Frost, I fast travel somewhere? Will he return to where I originally stole him, will he disappear forever, or can I own two horses simultaneously?  Ownership?  If he goes back to where I originally stole him, will I have to steal him again, and therefore never be his true owner again?  Two Horses?  The reason I'm asking is because I want to get Shadowmere (the Dark Brotherhood horse) while keeping Frost. Is it possible to do this, or will riding Shadowmere make me lose Frost forever? Setting Boundaries around city in google maps Is there a quick way to reset a .blend files windows and settings to default How to define a bijection between $(0,1)$ and $(0,1]$? How to define a bijection between $(0,1)$ and $(0,1]$?   Or any other open and closed intervals?   If the intervals are both open like $(-1,2)\text{ and }(-5,4)$ I do a cheap trick (don't know if that's how you're supposed to do it): I make a function $f : (-1, 2)\rightarrow (-5, 4)$ of the form $f(x)=mx+b$ by \begin{align*} -5 = f(-1) &amp;= m(-1)+b \\ 4 = f(2) &amp;= m(2) + b \end{align*} Solving for $m$ and $b$ I find $m=3\text{ and }b=-2$ so then $f(x)=3x-2.$  Then I show that $f$ is a bijection by showing that it is injective and surjective. Gnome terminal will not start I just tried to install python 3.6 on my Ubuntu 16.04 system, and now I can't run the terminal from the launcher or from Ctrl + Alt + T. I tried to run gnome-terminal from XTerm and got the following message:  Traceback (most recent call last):   File "/usr/bin/gnome-terminal", line 9, in &lt;module&gt;     from gi.repository import GLib, Gio   File "/usr/lib/python3/dist-packages/gi/__init__.py", line 42, in &lt;module&gt;     from . import _gi ImportError: cannot import name '_gi' Error in sys.excepthook: Traceback (most recent call last):   File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook     from apport.fileutils import likely_packaged, get_recent_crashes   File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in &lt;module&gt;     from apport.report import Report   File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in &lt;module&gt;     import apport.fileutils   File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in &lt;module&gt;     from apport.packaging_impl import impl as packaging   File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 23, in &lt;module&gt;     import apt   File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in &lt;module&gt;     import apt_pkg ModuleNotFoundError: No module named 'apt_pkg'  Original exception was: Traceback (most recent call last):   File "/usr/bin/gnome-terminal", line 9, in &lt;module&gt;     from gi.repository import GLib, Gio   File "/usr/lib/python3/dist-packages/gi/__init__.py", line 42, in &lt;module&gt;     from . import _gi ImportError: cannot import name '_gi'   How can I fix this error?  It should also be noted that:   My gnome-terminal file is now a python script. The gnome-terminal.real file will open the terminal as expected. python3.5 gnome-terminal will open the terminal as expected. Blender 2.8 : python code to switch shading mode (between wireframe and solid mode) If i switch between solid and wireframe mode, i can see in the info window that these commands are invoked :  bpy.data.screens["Layout"].shading.type = 'WIREFRAME' bpy.data.screens["Layout"].shading.type = 'SOLID'   Now i want to execute this command using python console. So i cut and paste the codes into python console but i got this error :   &gt;&gt;&gt; bpy.data.screens["Layout"].shading.type = 'WIREFRAME' Traceback (most recent call last):   File "&lt;blender_console&gt;", line 1, in &lt;module&gt; AttributeError: 'Screen' object has no attribute 'shading'  &gt;&gt;&gt; bpy.data.screens["Layout"].shading.type = 'SOLID' Traceback (most recent call last):   File "&lt;blender_console&gt;", line 1, in &lt;module&gt; AttributeError: 'Screen' object has no attribute 'shading'   Does anyone know why ? and what the correct script should i use in python console ?  Thanks How to escape braces (curly brackets) in a format string in .NET How can brackets be escaped in using string.Format? For example: String val = &quot;1,2,3&quot; String.Format(&quot; foo {{0}}&quot;, val);  This example doesn't throw an exception, but it outputs the string foo {0}. Is there a way to escape the brackets? Generalized RBF Kernels There is the notion of Generalized RBF Kernels, for example in "Towards Optimal Bag-of-Features for Object Categorization and Semantic Video Retrieval" from Jiang (1) or in formula (2.72) in  (2).  They define: Gen. RBF Kernel: $e^{-pd(x,y)}$, where (1) says d can be any distance function and (2) requires it to be a metric.  I now have been wondering for a long time: Is a function defined by $e^{-pd(x,y)}$ where d is a metric always a Mercer's Kernel? I think in (2) it sounds like it, but if it were true, not many people know of it, since they are still looking to prove that $e^{-EMD(x,y)}$ is a kernel, where EMD = Earth Mover's Distance, which is a metric.  If its not a Mercer's Kernel - do you know of any counter example? How long would the conference be for? I want to know if this is grammatically correct " How long would the conference be for?". A zero-dimensional ring is Noetherian? Proposition: Let $A$ be a non-zero ring that is not a field. Suppose $A$ is zero dimensional. Then it is Noetherian.   Proof: Let $p$ be a prime ideal of $A$. If $p$ is not maximal, then $p \subsetneq m$ for a maximal ideal $m$. Hence $dim A \ge 1$, contradiction. Hence every prime ideal is maximal. Consequently, every increasing (or decreasing) chain of prime ideals will be trivial in the sense that it will have length $0$. Hence the ring is Noetherian (and Artinian).  Is there a problem with the above proof? Proper fstab entry to mount a samba share on boot? I am a little confused on the proper fstab entry for a samba share in Ubuntu 12.04     I can get the drive to mount manually by using:  sudo mount -t cifs //192.168.2.2/raid_drive /mnt/homeserver -o username=jon,password=password  So I tried putting this in fstab:  //192.168.2.2/raid_drive /mnt/homeserver cifs username=jon,password=password,iocharset=utf8,mode=0777,dir_mode=07‌​77 0 0  Which gives me this error in syslog:  kernel: [ 2217.925354] CIFS: Unknown mount option mode kernel: [ 2217.936345] CIFS VFS: default security mechanism requested.  The default security mechanism will be upgraded from ntlm to ntlmv2 in kernel release 3.3  This  says to use smbfs although I believe smbfs is deprecated?   What is a common fstab configuration for a samba share in Ubuntu 12.04?   EDIT:  Using the accepted answer below I was initially getting this error message (from dmesg):  [   45.520883] CIFS VFS: Error connecting to socket. Aborting operation [   45.520990] CIFS VFS: cifs_mount failed w/return code = -115   although it turns out this was due to network connectivity issues, and not related to improper fstab entry. Why is the empty set considered an interval? What is the definition of an interval and why is the empty set an interval by that definition? I want to make a long shadow just like in this image.  I can create this shadow with shapes and by deleting the unwanted shadows after rasterizing the layer. But it's not very reusable. I can't resize the layer after rasterizing it.  Is there any easy way to make a long shadow like in the image below? How to delete a Test Class WITHOUT using eclipse I cannot install Eclipse, even if I wanted to.  It is not approved software for my org.  How can test classes be deleted from production, using deployments? There no 'active' checkbox when I am editing the classes in sandbox mode, so I can't just deactivate the test class, and i cant deploy a deleted class to prod...  how the heck is this done?  I dont want to use ANT or special software.  SF must have a native way to achieve this.  And if not...  then I am very disappointed in humanity. Reducing size of KML file (after converting from Shapefile) Need to develop a tapered spacer for under a car lift on an angled concrete slab I need to fabricate/develop an angled spacer.  13 inch wide by 10 inch long, by 3/4 inch to 1 3/8 inch thick. This spacer is needed to go under two of the posts of a hobbyist car lift in my garage. The garage floor is angled by the door where two of the four corner posts will go. These two rear posts need to be on a flat surface and at the same level as the two front posts.  Each post pad will need to handle approximately 2000 pounds. I was thinking of building a 4-sided mold where the column pads would be on the angled concrete and pouring some type of epoxy, resin, or cement into the mold. Which the metal plate from car lift posts would sit on. enter image description here I want to run an app in 'kiosk' mode for public unattended access via touch screen (no mouse or keyboard attached). I can already automate a network user logon and then the app launches (but only in last state - not necessarily full screen - which I want) I know with Workgroup Manager you can hide the dock, use simple Finder etc...but need something more powerful. Ideally it needs to monitor if the app crashes out and restart it / log limited user off and back on again.  Thanks  Phil Prove that $C\exp(x)$ is the only set of functions for which $f(x) = f'(x)$