I'm actually asking about my wife's MacBook Pro which I don't use very often. It's slowed down quite a bit recently and apparently before the update to El Capitan. Programs have started to take a long time to launch but once they have launched actually run fine. After booting up it will take about 45 seconds for Safari to even be usable. Spotlight also lags a lot and can't even keep up with typing, although it responds to 'escape' quickly.  I've watched the system monitor and even when programs are launching the CPU seems to be low with around 90% idle. It has 4GB of RAM and there always seems to be around 1.5Gb free.  I've attached the summary showing the hardware below. It doesn't have an SSD.  I've also run the Apple Hardware Test which took approximately an hour and nothing was reported from it.  From what I've read people have suggested upgrading the memory but since it doesn't seem to be running out of memory I would be surprised if this helped. There's also very little running and nothing user installed that is being launched in the Dock at start up.   Any help would be great and happy to provide any other stats needed.   Model Name:    MacBook Pro   Model Identifier:    MacBookPro9,2 Processor Name:  Intel Core i5 Processor Speed: 2.5 GHz Number of Processors:    1 Total Number of Cores:   2 L2 Cache (per Core): 256 KB L3 Cache:    3 MB Memory:   4 GB
I bought a Mac (13", early 2011) almost 5 years ago. When I first got it, it was running under OS X 10.7 and it was pretty fast. I've being upgrading it ever since and it's now running under Mac OS X 10.11.  I guess it didn't totally survive the upgrades because, today, there's a lot of bugs, freezes, lags, "spinning beach ball" appearing,... for example, when I write something on a normal program/editor, the cursor freezes for a few seconds, then catches up to what I'm writting.  As you can guess, that's really annoying! I've been thinkning about upgrading the hardware but I don't know what to do: should I change the RAM to 8 GB - 1 333 MHz (currently my computer has 4 GB - 1 333 MHz)? Or should I upgrade to an SSD (which is pretty expensive and difficult to install)?  Thank you very much.
How did the writers not notice that the mailbox of Leela's parents says "Turanga," and not "Leela"?  Turanga Leela is Leela's proper name, with Leela being her surname, so shouldn't it follow that her folks would be the same? How does TeX actually work? Leave only two decimal places after the dot Installing Wi-Fi driver for Realtek Semiconductor RTL8723DE Device [10ec:d723] How do I install Wi-Fi drivers for Realtek RTL8723DE device in Ubuntu 16.04?  lspci -v | grep -i network 02:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723 Java function for arrays like PHP's join()? Hidden fields though inheritance Counting buffer overlap in QGIS I have a 3-wire  that looks like this:    I'm trying to wire it up to my Arduino to detect changes in weight. From what I understand, the changes in voltage are so small that the Arduino can't detect the changes without amplifying the voltage. So I bought an  at  that looks something this:    I found  that shows how to wire everything up. However, I can't figure out the schematic and why they are using two load sensors instead of just one. They also mention resistors but I'm not sure why they are using them (and why the sizes they chose), or where in the circuit to put them.  Can someone please help me figure out how to wire this thing up to detect changes in voltage? Also, is there a way to do this by using only one of these sensors? This is what I've done so far:    The amp also has some pins that I don't understand: Offset null, NC. What are these pins for? Should I be using them?  Update: Now I am working with an Instrumentation Amplifier (). I also now have a 4-wire load sensor that I am playing with. Still can't get it to work, but I thought I would try to understand that before moving to the 3-wire load sensor. Persist sort/filter selections Catenatives followed by infinitives and gerunds permission denied BASH Installing PHP 5.3 in Ubuntu 14.04 Show that when $BA = I$, the solution of $Ax=b$ is unique I'm just getting back into having to do linear algebra and I am having some trouble with some elementary questions, any help is much appreciated.  Suppose that $A = [a_{ij}]$ is an $m\times n$ matrix and $B = [b_{ij}]$ and is an $n\times m$ matrix and $BA = I$ the identity matrix that is $n \times n$.  Show that if for some $b \in \Bbb{R}^m$ the equation $Ax = b$ has a solution, then the solution is unique. Allow more than one @name notification per comment Now this is probably a surprise to many since I always see thousands of comments like :  @Sarfraz, @balpha just told you they did in the first comment he wrote. Also, allowing only one Stack Overflow user to be logged in per IP address would be problematic for networks with shared IPs.  What's surprising is that apparently the notification will trigger only for Sarfraz and not for balpha. As you can see from the :  Only one person can be replied to at a time in a comment. The first one in the string wins.  I propose to increase the limit to let's say 3 or 5 people; it won't hurt (never seen that feature being abused) and especially many people believe it already works that way. Inverse of a matrix is expressible as a polynomial? Let $A$ be an $n \times n$ matrix. Prove that if A is invertible, then there exists a polynomial $p$, such that $A^{-1}=p(A)$  Thus far:  Let $W$ denote the $k$ dimensional A-cyclic subspace spanned by a vector $v$.  Then, $I_n=\sum_{i=0}^{k} a_{i}A^i$ for some scalar $a_i$.  What I want to do is multiply both sides by $A^{-1}$, so that way it just falls into my hands, but Im not sure that is 'legal'. Applications Not Reopening After Restart $\lim\limits_{n \to \infty} \frac{a_n}{b_n}=l$ ; Prove $\sum\limits_{k=1}^\infty a_k$ converges iff $\sum\limits_{k=1}^\infty b_k$ converges. Written, in Ex.8 Ch.9.1 of the book Advanced Calculus by P. M. Fitzpatrick :     Suppose that $\sum\limits_{k=1}^\infty a_k$ and $\sum\limits_{k=1}^\infty b_k$ are series of positive numbers such that $$\lim_{n \to \infty} \frac{a_n}{b_n}=l \ \ \ \text{and} \ l&gt;0.$$ Prove that the series $\sum\limits_{k=1}^\infty a_k$ converges iff the series $\sum\limits_{k=1}^\infty b_k$ converges.   Am I correct by the following (sketch of) proof? :  1- For a given $\epsilon_1$ there is $N_1$ such that $\left|\frac{a_n}{b_n} - l\right| &lt; \epsilon_1$ for all $n \ge N_1$.  2- Since the series $\sum\limits_{k=1}^\infty a_k$ converges, for a given $\epsilon_2$ there is $N_2$ such that $\left|b_{n+1}+\dots+b_{n+k}\right|&lt; \epsilon_1$ for all $n \ge N_2$ any for all natural numbers $k$.  3- Define $N = \max {\{N_1,N_2}\}$.   4- From Step (1), $a_{n+k} &lt; (\epsilon_1+l) b_{n+k}$ for all $n \ge N$ any for all natural numbers $k$. [Also, $a_i$'s and $b_i$'s are all positive]. Thus $a_{n+1}+\dots+a_{n+k} &lt; (\epsilon_1+l) (b_{n+1}+\dots+b_{n+k})&lt; \epsilon_3$. Then the convergence of the series $\sum\limits_{k=1}^\infty b_k$ implies the convergence of the series $\sum\limits_{k=1}^\infty a_k$.  5- For the reverse implication, we use the fact that $\lim\limits_{n \to \infty}\frac{a_n}{b_n}=l \iff \lim\limits_{n \to \infty}\frac{b_n}{a_n}= \frac{1}{l}= l' &gt;0$ and repeat the process this time for a and b exchanged.   6- The Quotient Property For Sequences hold for a nonzero limit in the denominator, but since the limit in the numerator also is zero so we may use the The Quotient Property For Sequences.    Thanks. What is the purpose of the Character Table in style files? What is the reason to insert the code below at the beginning of a style file? For example, the code below can be found on lipsum.sty.   %% \CharacterTable %%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z %%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z %%   Digits        \0\1\2\3\4\5\6\7\8\9 %%   Exclamation   \!     Double quote  \"     Hash (number) \# %%   Dollar        \$     Percent       \%     Ampersand     \&amp; %%   Acute accent  \'     Left paren    \(     Right paren   \) %%   Asterisk      \*     Plus          \+     Comma         \, %%   Minus         \-     Point         \.     Solidus       \/ %%   Colon         \:     Semicolon     \;     Less than     \&lt; %%   Equals        \=     Greater than  \&gt;     Question mark \? %%   Commercial at \@     Left bracket  \[     Backslash     \\ %%   Right bracket \]     Circumflex    \^     Underscore    \_ %%   Grave accent  \`     Left brace    \{     Vertical bar  \| %%   Right brace   \}     Tilde         \~} %%   What is it for? Strange artifacts along window borders after waking computer from sleep mode NB: Nvidia has released an official fix; please see ,  and/or .  Upon waking up Ubuntu 16.04 from Suspend, the following graphical glitches appear around all windows, context menus, and similar:      This is currently known to affect the following NVIDIA cards running the proprietary drivers:  NVIDIA GeForce 610M, driver version 375.39, 340.102 NVIDIA GT 630M, driver version 375.39 NVIDIA GTX 650, driver version 375.39 NVIDIA GT 740M, driver version 378.13 NVIDIA GTX 745, unknown driver version NVIDIA GTX 850M, driver version 375.39, 378.13 NVIDIA GT 940M, driver version 375.39 NVIDIA GTX 950M, unknown driver version NVIDIA GTX 960M, driver version 378.13 NVIDIA GTX 970, driver version 375.39 NVIDIA GTX 970M, driver version 375.39 NVIDIA GTX 980 TI, unknown driver version NVIDIA GTX 1060, driver version 375.26, 375.39, 378.09 NVIDIA GTX 1070, driver version 378.09  The above above list has been sourced from reports from other users here on AU,  thread, and  thread. NB: This is be no means an exclusive list. It probably effects nearly all Nvidia cards.  Furthermore, this issue has been replicated on a clean install where the only change was a software update and the installation of the latest NVIDIA drivers.  What is going on, and how can it be resolved? Connect iPhone to Mac Without Charging I am developing iOS apps and I hate, that always when I connect my iPhone to my Mac to install and test an app, the iPhone gets charged. Is there any possibility to connect my iPhone to my Mac without charging the phone?    My Environment: -  iPhone 4S (No Jailbreak) -  MacBook Air3,2 (Late 2010)