Unable to open Package Manager E: Malformed entry 1 in list file /etc/apt/sources.list.d/ros-latest.list (Component) E: The list of sources could not be read. Go to the repository dialog to correct the problem. E: _cache-&gt;open() failed, please report. W: Ignoring file 'ros-' in directory '/etc/apt/sources.list.d/' as it has no filename extension
How do I remove a malformed line from my sources.list? I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.
My actual question is to find the number of transversal given a collection of set ...  After a little bit of study it has come down to:  How can we count the number of matchings in a bipartite graph with parts of size $m$ and $n$ such that it covers all $m$ vertices of the first part, $m \le n$?  I already know that there is a way to count the number of perfect matchings in a bipartite graph with $m=n$ using the permanent of its (square) incidence matrix. Why do residuals in linear regression always sum to zero when an intercept is included? I'm taking a course on regression models and one of the properties provided for linear regression is that the residuals always sum to zero when an intercept is included.   Can someone provide a good explanation for why this is the case? Can Windows 7 be repaired to run with new motherboard? I have HP computer and it came with Windows Vista. It also had an option to upgrade to Windows 7 via upgrade disc. I have upgraded to Windows 7 via the special upgrade disc (It is special because it will only allow to install Windows 7 if Vista is already installed.  My motherboard recently died. I just replaced it and Windows 7 will not start up. It reboots and sometimes gives a blue screen of death. Very similar problem as described in this post: . Windows will not boot into normal or safe mode. Start up repair from system repair disc does not fix the problem. However, "" post on superuser describes that it should be possible to run Windows 7 on a new motherboard.  Is it hopeless to find a way to repair Windows 7 and I need to do a clean install? Is there a difference for repair options between OEM and retail versions of Windows 7? I remember doing this type of repair just fine in Windows XP days, so why am I unable to do so with Windows 7 - is it Microsoft or HP's fault? Should I stop buying HP computers or should I switch to Ubuntu? Solutions of $x^2 \equiv 1 \pmod N$ I am stuck with this exercise:     Show that $\forall s &gt;0 \quad \exists N &gt;0$ such that $$x^2 \equiv 1\pmod N$$ has more than $s$ solutions.   I think I cannot use the theory if quadratic residues, because the modulus is not prime, so maybe I must prove it with square roots or roots of unity, but I don't know how to approach it at all.  Thanks for any help. Why doesn't matter pass through other matter if atoms are 99.999% empty space? The ghostly passage of one body through another is obviously out of the question if the continuum assumption were valid, but we know that at the micro, nano, pico levels (and beyond) this is not even remotely the case. My understanding is that the volume of the average atom actually occupied by matter is a vanishingly small fraction of the atom's volume as a whole. If this is the case, why can't matter simply pass through other matter? Are the atom's electrons so nearly omnipresent that they can simultaneously prevent collisions/intersections from all possible directions? Prove that for for all $p,q\in \mathbb{Z}$, $q&gt;0$ we have: $$ \left| \sqrt{2}-\frac{p}{q} \right| &gt; \frac{1}{3q^2}. $$  To be honest, I do not know where to start - any help would be appreciated. Should I capitalise "or" between examples? On this site, there are often many different options as an answer, for example both with and without the Oxford comma.  When giving multiple options, should I capitalize the word "or" between them?  Option 1:     Eggs, butter and milk are dairy products   Or   Eggs, butter, and milk are dairy products     Option 2:     Eggs, butter and milk are dairy products   or   Eggs, butter, and milk are dairy products     Notice in Option 1 the "or" is capitalised. In Option 2 the "or" isn't. Other word for person who does something to others but does'nt like it done to them This is a duplicate question but has still not been answered for me. I'm so close to the exact word - I know there is one out there - but the closest word I can find is a hypocrite --     a person who claims to have certain moral principles or beliefs but behaves in a way that shows they are not sincere.    The word I'm looking for is a person who does not claim things, but does thing to another and they consider it wrong or immoral to have done to them. When is unbalanced data really a problem in Machine Learning? I have created the custom setting with the hierarchy type    I have added some fields to the custom settings  phone field is added to the custom settings  custom setting Name:Order_Configuration__c  Phone :12345 - one profile  phone:456798 - another profile   Is it possible to access the different values for different profiles in custom settings using apex trigger code How to reverse PCA and reconstruct original variables from several principal components? Principal component analysis (PCA) can be used for dimensionality reduction. After such dimensionality reduction is performed, how can one approximately reconstruct the original variables/features from a small number of principal components?  Alternatively, how can one remove or discard several principal components from the data?  In other words, how to reverse PCA?    Given that PCA is closely related to singular value decomposition (SVD), the same question can be asked as follows: how to reverse SVD? What's the best way to communicate between view controllers? Being new to objective-c, cocoa, and iPhone dev in general, I have a strong desire to get the most out of the language and the frameworks.  One of the resources I'm using is Stanford's CS193P class notes that they have left on the web.  It includes lecture notes, assignments and sample code, and since the course was given by Apple dev's, I definitely consider it to be "from the horse's mouth".  Class Website:   Lecture 08 is related to an assignment to build a UINavigationController based app that has multiple UIViewControllers pushed onto the UINavigationController stack.  That's how the UINavigationController works.  That's logical.  However, there are some stern warnings in the slide about communicating between your UIViewControllers.  I'm going to quote from this serious of slides:   Page 16/51:     How Not To Share Data         Global Variables or singletons         This includes your application delegate      Direct dependencies make your code less reusable         And more difficult to debug &amp; test         Ok.  I'm down with that.  Don't blindly toss all your methods that will be used for communicating between the viewcontroller into your app delegate and reference the viewcontroller instances in the app delegate methods.  Fair 'nuff.  A bit further on, we get this slide telling us what we should do.  Page 18/51:     Best Practices for Data Flow         Figure out exactly what needs to be communicated   Define input parameters for your view controller   For communicating back up the hierarchy, use loose coupling         Define a generic interface for observers (like delegation)         This slide is then followed by what appears to be a place holder slide where the lecturer then apparently demonstrates the best practices using an example with the UIImagePickerController.  I wish the videos were available! :(  Ok, so... I'm afraid my objc-fu is not so strong.  I'm also a bit confused by the final line in the above quote.  I've been doing my fair share of googling about this and I found what appears to be a decent article talking about the various methods of Observing/Notification techniques:   Method #5 even indicates delegates as an method!  Except.... objects can only set one delegate at a time.  So when I have multiple viewcontroller communication, what am I to do?  Ok, that's the set up gang.  I know I can easily do my communication methods in the app delegate by reference's the multiple viewcontroller instances in my appdelegate but I want to do this sort of thing the right way.  Please help me "do the right thing" by answering the following questions:   When I am trying to push a new viewcontroller on the UINavigationController stack, who should be doing this push.  Which class/file in my code is the correct place? When I want to affect some piece of data (value of an iVar) in one of my UIViewControllers when I am in a different UIViewController, what is the "right" way to do this? Give that we can only have one delegate set at a time in an object, what would the implementation look like for when the lecturer says "Define a generic interface for observers (like delegation)".  A pseudocode example would be awfully helpful here if possible. Show that $\int_0^ \infty \frac{1}{1+x^n} dx= \frac{ \pi /n}{\sin(\pi /n)}$ , where $n$ is a positive integer. Mannequin Duplication glitch How does a capacitor function in a 120V AC motor circuit? I don't understand the direction of current flow when a capacitor is wired in series with the start windings in, say, a fridge or other AC motor  running at/under 120V AC. Wiring diagrams seem to suggest that voltage energizes the hot leg of the circuit and current flows through the run windings and then returns via the neutral leg. Without a capacitor, the same thing would happen to the start windings. Problem there I guess is that both windings would be in phase and thus no spin created for the rotor. So, a capacitor is wired in series with the start windings which I kind of understand. But I don't know how the voltage and current behave. Does voltage energize the hot leg, flow through the start windings and then charge the capacitor? When voltage on the hot leg oscillates down to zero, does the capacitor discharge back toward the starter windings, or does current flow through the capacitor to the neutral leg? Basically I don't understand where the capacitor's charge goes when the hot leg is hot and when it is not. Lastly, is the capacitor placed between (downstream from) the start windings and neutral, or could it be wired between incoming voltage and the windings? Is there any difference between Present Perfect and Present Perfect Continuous? I have seen this construction quite often:      Online ads have been around since the dawn of the Web, but only in   recent years have they become the rapturous life dream of Silicon   Valley.   What is the rule there?. When your sentence doesn't start with pronoun + verb, invert them as verb + pronoun?. I know it sounds awkward but is it possible (grammatically correct) to use something similar to:      Online ads have been around since the dawn of the Web, but only in   recent years they have become...   And in any case, does this only work with have (or has)? Maybe it works fine with 'had' but I can't think of an example right now. Add 'Page' above page numbers in Table of Contents Salesforce query on profile not working on user language change I have a query on profile like  profilename = [Select name from profile where id=:userinfo.getUserprofileid ].name  Now I have a check in  VF page  like  profilename  == 'System Administrator' . this works fine if the logged in user language is english. If the user language is different then profile name will be  'System admin' in that language . So how to prevent this beahviour?   Also  is there any particular field in profile which I can use  to identify the profile is system admin? so that I can have check on that field instead of checking for name which is causing the problem, for example I think modifyall filed is only checked for system admin. How do I specify a pointer to an overloaded function?