Error NullReferenceException
What is a NullReferenceException, and how do I fix it?
How do I sudo a command in a script without being asked for a password? I'm new to blender and trying to model the blade of my helicopter and can't figure out how to make an edge curved (for the red tip and selected edge). The object is a plane, with one loop cut. I attempted making a bevel Ctrl B, but nothing happens (A dotted line appears attached to the cursor, moving does nothing, left-clicking does nothing).  also I cant add a curve modifier, just says its disabled. What is the correct way to model this? Is there a continuous function such that $\int_0^{\infty} f(x)dx$ converges, yet $\lim_{x\rightarrow \infty}f(x) \ne 0$? Evaluate $$ 1 + \frac{1}{3}\frac{1}{4}+\frac{1}{5}\frac{1}{4^2}+\frac{1}{7}\frac{1}{4^3}+\dots$$  All i could do was to see that $$\frac{1}{3}=\frac{1}{2.1+1},\frac{1}{5}=\frac{1}{2.2+1},\frac{1}{7}=\frac{1}{2.3+1},\dots$$  SO, we should be able to write   $$ 1 + \frac{1}{3}\frac{1}{4}+\frac{1}{5}\frac{1}{4^2}+\frac{1}{7}\frac{1}{4^3}+\dots=1+\sum_{n=1}^{\infty}\frac{1}{2n+1}.\frac{1}{4^n}$$  This is what i could simplify the given question to...   But, this is doing me no good.. I could not go any further..  I would be thankful if some one can help me to clear this.  I would request users who are trying to help me to just give necessary hints but not post it as answer.  Thank You. set fontsize for TikZ figure Convert a list to a string in C# Equivalent Resistance? How do you find the equivalent resistance here? (I realized it's a Wheatstone bridge, but it's unbalanced, so that doesn't help.) I tried using Kirchhoff's laws, but there is no cell given. Relativity Of Simultaneity Confusion Was this an oversight?  Or is it to do with the JVM? importing a multipage PDF file into InDesign CC When I place a multipage pdf file into InDesign CC, the pages go outside of my document settings, making this function useless.  What do I have to do to make the placed  pdf pages go within my document settings, which in this case is 11 in. Length X 8.5 in. width, .5 in. margins on all sides, with two columns per page. I would greatly appreciate an answer to this, Thank you. Proving a function is Lipschitz continuous Show that the following function is Lipschitz continuous and find a Lipschitz constant  $$y\mapsto f(x,y)\\ f(x,y)=\frac{y}{x}\ln(\frac{y}{x})\text{  , } |x-1|\leq\frac{1}{2}\text{  , } |y-e|\leq\frac{e}{2} $$  I have no clue on where to begin to prove this.   My first question is how I should interpret this function, is $x$ a sort of constant? TZInfo::DataSourceNotFound error starting Rails v4.1.0 server on Windows Does being refused entry to Singapore mean I am now blacklisted? My friend who is an Indonesian citizen tried to enter Singapore this week and was refused entry at the Singapore Harbour Front Ferry Terminal by immigration.  This was his first trip overseas and is not used to international travel, so due to his inexperience and that he was excited to go to Singapore, he possibly made some mistakes on trying to be granted access into Singapore.   He was told he was to enter a Singapore address for his stay or a friend or relative he will stay with. He was only staying for one day and was going to catch the ferry back at night, so he had no plan to stay in Singapore and as such had no address to put. They then asked why he was traveling alone and that he should travel with somebody for his first trip. He told them he always travels alone in Indonesia and finds it easier to see and do things alone. He was then asked why he was entering Singapore and the reason he gave was to purchase some electronics which he cannot buy in Indonesia. They asked for how much money he had and they then advised that he did not have enough money to purchase the items he was after. They refused his entry and he was then escorted to a ferry and returned to Indonesia. His passport was not stamped and he was not fingerprinted.   He was given a Notice of Refusal of Entry which had the reason as "Being ineligible for the issue of a pass under current immigration policies" form on his departure. Also included on this form is his passport number etc. He was not advised of him being banned or a time frame that he cannot enter Singapore.  My questions are: Has he been banned or restricted to enter Singapore for a period of time? When entering countries including Singapore, does he need to tick the box stating he has been refused entry into another country? I am hoping to get my friend to Australia at the end of the year for a 10 day holiday and will this hinder his chance of getting a visa and entering Australia? Make font size bigger than max limit of 1296 pt in Adobe Illustrator (2015)? For some reason and for many years there's a limit for font size in Illustrator. It is 1296 points max, so you can't go bigger without converting type to outlines first. Converting to outlines means you will not be able to edit type parameters and text it-self. Don't know how about you, but this makes me sad in non-destructive editing era.  What's your workaround? Who are the diamond moderators, and what is their role? Some people have a diamond after their username (e.g. )    What special privileges do diamond moderators have? How can I become a diamond moderator? Who are the diamond moderators?  How many are there?      For more information, see  in the .     Note: not to confuse with certain Stack Exchange employees, for example  members or "community managers", who often have diamonds as well, but are not ordinary moderators. How does chain fishing work? I would like to know how to understand/analyse the circuit below. And sorry but my level in electronics is not that high and I could only tell that the opposing transistors on the left are meant to cancel any current from the input , yet I don't really understand the B stage which I think the C stage is well related to , and if I wanted to analyse the nodes around the circuit apart from (A,B,C) How can I do it ?  Is it by measuring the current on resistors/nodes?  and note that the output voltage of the circuit in node C is zero this is what it meant to be.I would appreciate any help.  Regards What is Ubuntu's status on the Meltdown and Spectre vulnerabilities? Any questions relating to status updates, or asking if anything is going to be patched for these vulnerabilities should be closed as duplicates of this question.    are in the news right now and sound pretty severe. I don't see any security updates from Ubuntu that cover these vulnerabilities.  What is Ubuntu doing about these vulnerabilities, and what should Ubuntu users be doing?  These are CVE-2017-5753, CVE-2017-5715 and CVE-2017-5754. How do I unset an element in an array in javascript? So I understand that Euclidean distance is valid for all of properties for a metric. But why doesn't the square hold the same way?