Attaching CGPDFPageRef to MFMailComposeViewController
How to attach CGPDFDocument/CGPDFPage to MFMailComposeViewController
Lie bracket for Lie algebra of $SO(n,m)$ How does one show that the bracket of elements in the Lie algebra of $SO(n,m)$ is given by  $$[J_{ab},J_{cd}]  ~=~ i(\eta_{ad} J_{bc} + \eta_{bc} J_{ad} - \eta_{ac} J_{bd} - \eta_{bd}J_{ac}),$$  where $\eta$ has is the definite symmetric form with signature $(n,m)$? hard disks spin up by processes / applications that simply get a list of disks? How to prevent? I have a 24/7 always-on Debian Jessie based headless home server that has a large 1TB SSD for the OS and all of my frequently accessed files. This same system has 4 larger hard disk drives in a SnapRAID array. These are mainly for archiving infrequently accessed Blu-rays and want those drives to remain spun down in standby unless I actually read or write to them. They are all formatted as ext4 and mounted with noatime and nodiratime enabled.  So even though no process or program should be regularly accessing those drives in any direct way, the hard drives constantly get spun up from standby. It seems to be related to graphical programs that provide a gui file browser, even something like Chromium. If I don't even browse into those drives, I'm thinking that these processes by simply getting a list of available drives spins up the hard disks. Much like blkid does. The problem is, it's hard to determine the root cause of this since none of these processes are actually reading or writing the filesystem on those drives, so no files are actually changing or being touched. Is there some sort of cache that I can populate or a buffer to prevent these programs from spinning up the hard drive simply by getting a list of available disks? This is honestly driving me insane, since I can't find a reliably way to keep these disks spun-down even though there is no direct access of the filesystem.  UPDATE: Thanks to Stephen's answer, I was able to trace the disk activity to gvfs and udisks. It's a real shame that these processes insist on waking up disks in standby when they aren't actually being accessed to do any real I/O with the filesystem. So far I just uninstalled them, knowing that it will remove some functionality from PCManFM and the like. Plotting a function with an argument in degrees I want to plot a function. The function is, F is proportional to x/cos(x). Here x is rotation in degree and F is the force. I have to plot the graph where the x axis will be from 0 to 70 degree and the y axis will be linear value 0 to 5. I am not able to find any option to draw graphs where x axis is with rotational degree. Ethernet: how important is the magnetics topology? I have some Ethernet issues with a set of boards (6/10 are bad). They're possibly just assembly house mistakes... but I'm very concerned about my magnetics jack.  I could have sworn I saw a example schematic with my jack's topology used with my PHY before, but I can't find it. The PHY's datasheet and suggested magnetics jacks are all identical in topology, and very different than what I have.  I'm using a SMSC  PHY, with a Bel  magnetics jack.  The transformer ratios on my jack vs. a suggested jack for this PHY like the  are the same (1:1).  The inductance is the same, 350uH. However, the choke on mine is on the circuit side, not network side. Also, while the TLA has four 75 ohm resistors from taps tied to a single 1nF/2kV cap, mine has an extra set of 1nF caps between the taps and the 75 ohm resistors.  The main difference is that my jack is a POE jack, and I thought I found an example that used one exactly like it. So, the topology is obviously different just because of that feature.  At the moment, I have 4 good boards, 1 'sometimes' board, and 5 boards that just blink a LED at 11.68Hz representing some error that no datasheet explains.  How important is this? Of course there's no other jack with that footprint.  EDIT  I added some detail on the magnetics jacks above. I was just recommended the SI-60152-F, so I'll compare to that one. Of course like all the other recommendations... it also has no stock at anyone on FindChips.  LATE EDIT  It turns out my problem was the crystal layout that fed the Ethernet PLL.  On the respin, I went with a more standard non-POE jack. Using Regular Expressions to Extract a Value in Java I have several strings in the rough form:  [some text] [some number] [some more text]   I want to extract the text in [some number] using the Java Regex classes.  I know roughly what regular expression I want to use (though all suggestions are welcome). What I'm really interested in are the Java calls to take the regex string and use it on the source data to produce the value of [some number].  EDIT: I should add that I'm only interested in a single [some number] (basically, the first instance). The source strings are short and I'm not going to be looking for multiple occurrences of [some number]. What would be the best way to calculate someone's age in years, months, and days in T-SQL (SQL Server 2000)?  The datediff function doesn't handle year boundaries well, plus getting the months and days separate will be a bear.  I know I can do it on the client side relatively easily, but I'd like to have it done in my . How to determine the current widget's parent container (sidebar widget id) Convert UTC date time to local date time Consider the following snippet:  $$\text{d}_{H}(A,B)  = \max\left\{ \sup_{a\in A} \inf_{b\in B} \text{d}(a,b),\sup_{b\in B} \inf_{a\in A}\text{d}(a,b)\right\}$$     In the output, the text under the inf's is significantly smaller then the one under the sup's. The same happens when I have it in an align environment.  You can see the same problem in the wiki definition of the . How can I have the typeset under the inf's and sup's in the same size? Open all iCloud tabs from iPhone on Mac TLDR; Is there a way to simultaneously open all iCloud tabs saved on iPhone, on a Mac?  I use my iPhone for browsing and as a means of "read it later" I just leave the open tabs there with the purpose of opening them all later on my Mac. Is there a way to open them all (much like Chrome allows in the "Tabs from other devices" in History page)? Why would a spinning space station create a centrifugal force on an astronaut rather than simply spinning around him/her? We often see films with spinning space station that create  by having the astronauts pulled outwards by centrifugal force.  I'd like to know if this would really happen, and if so, why is the following scenario not true:   Take an astronaut in open space. He doesn't move. Put a big open spinning cylinder around him - surely he still doesn't move. Close the cylinder. I still see no reason for him to be pulled outwards. Why are there no other dragons in ASOIAF? Send Ctrl+Alt+F1, Crtl+Alt+F7 into VirtualBox Hi there! I'm looking for a help drawing this diagram. Any ideas? If perimeter of a triangle is $2d$, what is the length of sides so the triangle has maximal area?    I found some solution using circle and angles, but I think I have to use derivatives.    I need help. In Korea, we learned that we should use the past tense when the subject is an historical event, as in "The Korean war broke out in 1950."  However, I think that when the event continues to affect the present (now), we should use the present perfect.  So I think that we can say 'The Korean war has broken out in 1950.'  Am I right? How to derive variance-covariance matrix of coefficients in linear regression Looking for a title of a sci-fi novel or story where a government department's job was to slow things down URLs: Should I use hyphens, underscores or plus symbols? Which is better for search engines?   example.com/my_cool_page.html example.com/my-cool-page.html  example.com/my+cool+page.html Input file1 is:  dog 123 4335 cat 13123 23424  deer 2131 213132 bear 2313 21313   I give the match the  pattern from in other file ( like dog 123 4335 from   file2).  I match the pattern of the line is dog 123 4335 and after printing all lines without match line my output is:   cat 13123 23424 deer 2131 213132 bear 2313 21313   If only use without address of line only use the pattern, for example 1s how to  match and  print the lines?