javaFX getting nullpointer exception when trying to set BarChart from different controller
What is a NullPointerException, and how do I fix it?
How do I get the deformed coordinate of a vertex with Python? How might someone find the deformed coordinate via Python or otherwise when using a subdivision modifier with the 'show on cage' option?  For example, a subdivided cube with cage enabled and a vertex selected shows the location of the vertex at 1,1,1 but when manually placing the cursor near on the surface it is closer to .5,.5,.5  I know the vertex location needs to be at its non-deformed location for subdivision to even work but would like to get more accurate point locations at the surface without having to apply to mesh. PostgreSQL create line from points Should not we apply pseudo-forces all the time as the Earth is a non-inertial frame of reference? I made changes to iptables config file in /etc/iptables/filter in Ubuntu and want to reload them. I read the man page and also googled but couldn't find the information. Any help will be appreciated. short view distance in 3d view? Do objects rotate around the torque vector or its center? If a sphere has a torque vector coming out of it at point A, would the sphere rotate about its center or the axis of the torque vector? Some irreducible character separates elements in different conjugacy classes Let $x$ and $y$ be elements that are not conjugate in $G$.  Then there is some irreducible character $\chi$ such that $\chi(x) \not = \chi(y)$.   Clearly the "irreducible" part isn't important, since any character can be written as the sum of irreducible characters, but I'm having trouble going beyond that.  I'd appreciate a good hint over a full answer, and I'd be most interested in a way to construct a group representation $\varphi:G \to GL(V)$ of $G$ such that the character of the representation takes different values on $x$ and $y$. Robust method to extract "pure" part of a variable I am trying to perform a multi linear regression model:  $$y_i = β_0 + β_1x_{i1} + β_2x_{i2} +... + β_px_{ip} + ε_i$$  where $$x_{i1}, x_{i2}, ..., x_{ip}$$ are highly correlated with each other (VIFs can be as low as 5 and high as 30).  I am just wondering if there exists a procedure with the following properties:  1) extracts the pure part of each independent variable, where pure is defined as a part of the variable which is uncorrelated with other variables.  2) the pure part and the original variable should be similar to each other, whether similar is defined as moments such as mean and variance and correlation coefficient (ideally >0.90) Display each sub-directory size in a list format using one line command in Bash? I want to get a list of the directories and their sizes in a list format like how you get when you do a ls -l.  The thing is that is there a one line command that can do this? I see others have long commands just to output this. That's just too long.  What command can do this or combination of commands that can be easily typed? du -h gives it, but it displays all of the sub-folders which is not what I want. just the current directories folders. number of prime ideals in algebraic integers Ignore python multiple return value Say I have a Python function that returns multiple values in a tuple:  def func():     return 1, 2   Is there a nice way to ignore one of the results rather than just assigning to a temporary variable? Say if I was only interested in the first value, is there a better way than this:  x, temp = func() Is "until" inclusive or exclusive? I sent an email to someone and got an auto-reply saying:     I am out of the office until 09/15/2014.   Does this mean he will be available on the morning of the 15th? What algorithm is used by computers to calculate logarithms? We can click the website mentioned by the users in their profile page. They can enter anything that  be .   But, in  profile page, the website link is not clickable. Why not? How can I show that $y'=\sqrt{|y|}$ has infinitely many solutions? Show that the first order differential equation $y'(x)=\sqrt{|y(x)|}$ with intial value $y(1/2)= 1/16$ has infinitely many solutions on the interval [−1, 1].  My thought were to show that this equation has two solutions (just by ansatz, or just looking at the interval $]0, 1]$ to get $y'(x) = \sqrt{|y(x)|}$) and deduce from that that there must be infinitely many solutions since the solution set forms a vector space. I've got a nagging feeling this isn't the way to go though. Can anybody give me a hint where to look? Why less temperature at high altitude Why there is always cold at high altitudes. e.g. at peak of mountains. Also as we go high from sea level, temperature starts decreasing. Why is it? Can Superman see through his eyelids? Can we get notification in the tab (change of title)? I'm usually running many different StackExchange sites in Firefox using tabs (using ReloadEvery to update every 5 minutes).  Right now to check for activity, I have to manually click on the tab to see if the envelope is lighted.  How about making the icon on the tab i.e. the title text change in some way, denoting that you have activity on the page?  We already add a message count for the chat tabs, so this shouldn't be very complicated.  Possible Example: Customize feed on stack exchange android app How do I check the series $\sum_{n=2}^{\infty} \frac{(-1)^n }{n+(-1)^n}$ for absolute convergence/conditional convergence ?  How can I solve this problem?