When I compile my schematic, I get some errors in the compile window. When I double click them it zooms in on them and highlights them with a mask. How do I get rid of that mask?
I can't work out why Altium is doing this, or how to undo it, or how to make it stop doing it.  It happens when I use the 'Find Similar Objects... ' option; all of objects that it hasn't found are faded out and I can no longer select them.  Anyone know how to fix this?  Additionally, if anyone knows how to change, en masse, the components' footprint library to 'Any' through the SCH inspector, that'd be really helpful too.
Invertibility of the Product of Two Matrices I have shown that if two $n\times n$ matrices $A$ and $B$ are invertible, then $AB$ is also invertible. I am having problems though with showing that $(AB)^{-1}=B^{-1} A^{-1}$. I thought of using their left-multiplication transformations but it seems that this is only associative and not commutative so I can reverse $L_A L_B$ Technique for finding the centerline of a curved object? I'm curious to know if anyone knows of any effective techniques for finding the center line of a curved object.  In the screenshot below you'll see a crude version of what I mean.     Is there any way to get that line to perfectly trace the center, or is it easiest to just eyeball it?  Photoshop or Illustrator techniques are acceptable. What is a "year" in Westeros? jQuery: Javascript throws Error "The operation is insecure" when setting value How to get from Nice to Monaco by public transport? What's the simplest and cheapest way to get from central Nice, France to Monaco by public transportation? Can I color text by using an image, so that the color isn't flat? I'm using tikz to attempt to make a book cover, and I have a "wallpaper" image that looks like leather (not that I've handled that many leather-bound books). I'm using the node command to place text over the top of it, but none of the colors I've experimented with look decent.  Can I use an image of gold-leaf as the fill/stroke for the text? Or for that matter, for the path lines as well?  I've tried googling for this, but I can't figure out a set of keywords non-generic enough to pull back useful results. Limit as $x\to 0$ of $\frac{(1+x)^{1/x}-e}{x}$ It is often stated that the Lagrangian formalism and the Hamiltonian formalism are equivalent.   We often hear people talk about eigenvalues of Hamiltonians but I have never ever heard a word about eigenvalues of Lagrangians.   Why is this so? Is it not useful? is it not possible to do it? Suppose we have two short exact sequences in an abelian category $$0 \to A \mathrel{\overset{f}{\to}} B \mathrel{\overset{g}{\to}} C \to 0 $$ $$0 \to A&#39; \mathrel{\overset{f&#39;}{\to}} B&#39; \mathrel{\overset{g&#39;}{\to}} C&#39; \to 0 $$ and morphisms $a : A \to A&#39;, b : B \to B&#39;, c : C \to C&#39;$ making the obvious diagram commute. The snake lemma states that there is then an exact sequence $$0 \to \ker a \to \ker b \to \ker c \to \operatorname{coker} a \to \operatorname{coker} b \to \operatorname{coker} c \to 0$$ where the morphisms between the kernels are induced by $f$ and $g$ while the maps between the cokernels are induced by $f&#39;$ and $g&#39;$.  It is not hard to show that the morphisms induced by $f, g, f&#39;, g&#39;$ exist, are unique, and that the sequence is exact at $\ker a, \ker b, \operatorname{coker} b, \operatorname{coker} c$. With the use of a somewhat large diagram shown , we can even construct the connecting morphism $d : \ker c \to \operatorname{coker} a$. However, I'm stuck showing exactness at $\ker c$ and $\operatorname{coker} a$. I thought Freyd might have had an element-free proof in his book, but it turns out he proves it by diagram chasing and invoking the Mitchell embedding theorem [pp. 98–99]. Is there a direct proof? I just installed Ubuntu 12.10 on an ASUS X401U, and after installation there is no list of wireless connections. I didn't have that problem with an installation on HP. What I can do to enable Wifi?  07:00.0 Network controller [0280]: Ralink corp. Device [1814:3290] What's the easiest way to play a sound file (.wav) in Python? By easiest I mean both most platform independent and requiring the least dependencies. pygame is certainly an option, but it seems overkill for just sound. How do I determine the size of an object in Python? I want to know how to get size of objects like a string, integer, etc. in Python.  Related question:   I am using an XML file which contains size fields that specify the size of value. I must parse this XML and do my coding. When I want to change the value of a particular field, I will check the size field of that value. Here I want to compare whether the new value that I'm gong to enter is of the same size as in XML. I need to check the size of new value. In case of a string I can say its the length. But in case of int, float, etc. I am confused. Polling the keyboard (detect a keypress) in python How can I poll the keyboard from a console python app?  Specifically, I would like to do something akin to this in the midst of a lot of other I/O activities (socket selects, serial port access, etc.):     while 1:       # doing amazing pythonic embedded stuff       # ...        # periodically do a non-blocking check to see if       # we are being told to do something else       x = keyboard.read(1000, timeout = 0)        if len(x):           # ok, some key got pressed           # do something   What is the correct pythonic way to do this on Windows?  Also, portability to Linux wouldn't be bad, though it's not required. In a sentence taken from the Oxford Dictionary:     ‘The inscription on his tombstone in Groombridge Church, where he is buried alongside his three children, bears his original name and no reference to his nom de plume.’   Is ‘buried’ an adjective, a , or a   because it follows the copular verb is?      Predicate nominatives complete only linking verbs. The linking verbs include the following: the helping verbs is: am, are, was, were, be, being, and been; the sense verbs: look, taste, smell, feel, and sound; and verbs like become, seem, appear, grow, continue, stay, and turn.   Or is it a past participle because the clause is in the passive voice?   Does “he is buried” mean currently his body lies in a coffin covered with soil, or  does it mean he has been buried by someone?  If we say ‘he was buried’ it clearly refers to an event that happened and ended sometime in the past. It might even suggest that the burial ground has since been changed. I have several input and option elements on my page, each (well almost) have an event attached to update some text on the page once they change. I use jQuery which is really really cool :)   I also use Microsofts  framework, utilizing the UpdatePanel. The reason why I do that is that certain elements are created on the page based on some server-side logic. I don't really want to explain why I use the UpdatePanel - even if it could (it can with quite some effort) be rewritten to use only  I still want that UpdatePanel.  You probably guessed it - once I have a postback on the UpdatePanel the jQuery events stops working. I actually was expecting this, since the "postback" is not really a new postback so my code in document.ready that binds the events won't be fired again. I also confirmed my suspicion by reading up on it in the jQuery help libraries.  Anyway I'm left with the problem of rebinding my controls after the UpdatePanel is done updating the . I preferably need a solution that does not require adding more .js files (jQuery plug-ins) to the page but something as simple as being able to catch the UpdatePanel's 'afterupdating' where I can just call my method to rebind all the form elements. Injectivity of Homomorphism in Localization Let $\alpha:A\to B$ be a ring homomorphism, $Q\subset B$ a prime ideal, $P=\alpha^{-1}(Q)\subset A$ a prime ideal. Consider the natural map $\alpha_Q:A_P\to B_Q$ defined by $\alpha_Q(a/b)=\alpha(a)/\alpha(b)$. Suppose that $\alpha$ is injective. Then is $\alpha_Q$ always injective?    I think so, but I'm clearly being too dense to prove it! My argument goes as follows.  Let $\alpha(a)/\alpha(b)=0$. Then $\exists c \in B\setminus Q$ s.t. $c\alpha(a)=0$. If $B$ is a domain we are done. If not we must exhibit some $d\in A\setminus P$ s.t. $da=0$. Obviously this is true if $c =\alpha(d)$. But I don't see how I have any information to prove this!  Am I wrong and this is actually false? If so could someone show me the trivial counterexample I must be missing?   Many thanks! What can I expect from a Skype interview for PhD admissions? How to demystify the axioms of propositional logic? How might I go about getting some intuition on the typical axiom schemes given for propositional logic? They seem rather mysterious at first glance.  For example, these are taken from:    $\phi \to \phi$ $\phi \to \left( \psi \to \phi \right)$ $\left ( \phi \to ( \psi \rightarrow \xi \right)) \to \left( \left( \phi \to \psi \right) \to  \left( \phi \to \xi \right) \right)$ $\left ( \lnot \phi \to \lnot \psi \right) \to \left( \psi \to \phi \right)$ Mid 2012 MBP shuts down claiming no power with charge at 30% or 40% or more I have two mid 2012 MBPs. Sometime last year they both started randomly shutting down and showing the 'please plug me in to power' image when trying to start them up. That would be fine if the batter was at 1% or less but this happens when the battery is at anywhere from 30% to as high as 48% full. The power cycle info says 500 cycles or so. Both of them do this. They are both patched current, always. I asked Apple they suggested NVRAM PRAM and SMC reset, as expected, which had no effect. Any ideas? Where has all the RAM gone? I have 1GB of RAM, and when I run NetBeans and Firefox, they get about 300MB of RAM. At some point, the system becomes very slow, probably 100 times slower than normal, switching windows (Alt+Tab) becomes a huge task and the computer is practically useless. This is probably the moment when it starts to swap.    Two questions:   According to images provided, where has all the RAM gone? When I calculate all the processes memory, it is far smaller then 1GB. Is it normal for system to become 100 times slower when the RAM is full and using swap space?   On another computer with 4GB of RAM I have no problems.     Update: I added 2GB of RAM, now I have 3GB. Anyone who wants to use heavy apps with 1GB on Unity, I don't think it's going to work. Works fine on an empty desktop :)