How to store a Preferred Contact?
How to have a one-to-many relationship with a privileged child?
When I created my account, I used Facebook Connect as my only login type and I can only log in to my account using it.  I wish to create a Stack Exchange login to be able to log in with instead of Facebook Connect, but I can't find how to do this. It seems that the option for creating a Stack Exchange login is only present when creating a new account? Valid characters in a Java class name Do I have an SSD and a hard drive on my MacBook Pro? I looked at the details provided in  my system report/storage and I noticed that it appears I have a hard drive of 499.05GB and an additional SSD drive of 499.42GB. Does this mean I have 1TB of data? I only have 139GB available so do I have 500GB 'hiding' somewhere? (If so where??)  I am unsure how to interpret this information- why does it list both storage types? Is it duplicating the information?     Macintosh HD:      Available:    139.8 GB (139,800,666,112 bytes)   Capacity: 499.05 GB (499,046,809,600 bytes)   Mount Point:  /   File System:  Journaled HFS+   Writable: Yes   Ignore Ownership: No   BSD Name: disk1   Volume UUID:  EF0908C8-XXXX-XXXX-XXXX-XXXX80333709         Logical Volume:  Revertible:  Yes (unlock and decryption required)   Encrypted:    Yes   Encryption Type:  AES-XTS   Locked:   No   LV UUID:  8CC9C88D-XXXX-XXXX-XXXX-XXXX2002329B        Logical Volume Group:   Name:    Macintosh HD   Size:    499.42 GB (499,418,034,176 bytes)   Free Space:  18.9 MB (18,903,040 bytes)    LVG  UUID: EE040070-XXXX-XXXX-XXXX-XXXXA83B309         Physical Volumes:      disk0s2:     #is this a second disk?      Device Name:  APPLE SSD SM0512G   Media Name: APPLE SSD  SM0512G   Media   Size:   499.42 GB (499,418,034,176 bytes)   Medium Type:  SSD    Protocol:  PCI    Internal:  Yes   Partition Map Type: GPT(GUID Partition Table)  #does this mean its partitioned?   Status: Online   S.M.A.R.T. Status:  Verified   PV UUID:    A1391405-XXXX-XXXX-XXXX-XXX2E8FCDF3 Fibonacci proof question: $f_{n+1}f_{n-1}-f_n^2=(-1)^n$ I have 1-band GeoTIFF file. The color interpretation for band is gray. I want a color table in order to transform my Col.tiff to Col.jpeg or Col.png.  I tried putting a color table in this tiff via a .vrt:  gdal_translate -of VRT  Col.tiff Col.vrt   then adding in the .vrt:  &lt;ColorInterp&gt;Palette&lt;/ColorInterp&gt; &lt;ColorTable&gt;    &lt;Entry c1="0" c2="0" c3="255" c4="240"/&gt;    &lt;Entry c1="0" c2="0" c3="254" c4="240"/&gt;    &lt;Entry c1="0" c2="0" c3="253" c4="240"/&gt;    &lt;Entry c1="0" c2="0" c3="252" c4="240"/&gt; &lt;/ColorTable&gt;   And translate again :  gdal_translate Col.vrt Col.tiff   But it answered:  Warning 1: Unable to export color table to GeoTIFF file.  Color tables can only be written to 1 band or 2 bands Byte or UInt16 GeoTIFF files.   How can I do it?  For information, there is gdalinfo for the Band:  Band 1 Block=55x18 Type=Float64, ColorInterp=Gray   Description = Something   Metadata:     GRIB_COMMENT=Something[p]     GRIB_ELEMENT=TMP     GRIB_FORECAST_SECONDS=0 sec     GRIB_REF_TIME=1401926400 sec UTC     GRIB_SHORT_NAME=SMTHG     GRIB_UNIT=[p]     GRIB_VALID_TIME=1401926400 sec UTC How can I tell what RAM will fit my computer? If I want to add more RAM to my computer, how can I buy something compatible? What kinds are there? How do I determine which kind my computer will accept and how much I can add? I took a look at  but my question is not the same.  I have unique keys encrypting each plaintext (in CBC mode, AES-256) and I do not use a key to encrypt more than one plaintext. Is it insecure to use null IVs in this case? If it is insecure, why? From the Cracks in time and space story arc it's known that if a TARDIS is blown up (possibly while in the Time Vortex) it rips creation itself apart. Also, from the Stolen Earth / Journey's End we learn the Daleks' masterplan which is subjugating creation itself via destroying it with the Reality Bomb (unfading Z-neutrino energy radiation).  In the Last Great Time War all sorts of temporal weapons were used and it's known that Daleks have the ability of time travel as well. Why didn't they use the Time Vortex back then to win the war once and for all via detonating a TARDIS while inside? Why do we use the object instead of the subject pronoun in constructions like "stupid me"? I'm trying to find out how come we say lucky me and stupid us rather than lucky I and stupid we. My understanding is that this is not a recent invention, but a relic from the distant past where it was a dative construction. However, I don't see the reason for using any case other than the nominative in this construction to begin with.        He went surfing. → Lucky him went surfing.   I got pulled over. → Stupid me got pulled over.   They bought a house. → Thoughtless them bought a house.      This is rather intriguing. After thinking about it for a while, I couldn't come up with any other language, Germanic or otherwise, where simply introducing an adjective would dictate a change of grammatical case. This appears to be an English peculiarity. How far can it be traced back? Can anyone comment on its background? I want to typeset a piece of code containing line breaks.  New lines should indent to a specified point in the previous line.  Here is a monospaced example to illustrate what I mean.  Notice how 'case' and 'of' line up below, as well as 'let' and 'in':  swap : forall a, b. Tuple a b -&gt; Tuple b a swap a b x = case x              of tuple a b y z. let x' = tuple b a z y                                in x'   The code I want to typeset is not monospaced, so I can't just use a verbatim environment to get what I want.  The actual LaTeX of the first line, for instance, is  \mathsf{swap} : \forall\alpha,\beta.\;\mathsf{Tuple}\;\alpha\;\beta\to\mathsf{Tuple}\;\beta\;\alpha   How can I align some text to a specific point in the previous line? Is there an efficient way to copy text from a PDF without the line breaks? How to capture the scene exactly as my eyes can see? I'm taking Calculus II next semester so I don't have all the tools from it to back me up but something came up in a discussion this evening that asked me to prove that the following sequence converges. As I'm new to formal math I'm hoping someone can verify my proof, especially step $6$. I must prove that $$\lim_{n\to\infty}P_n=b$$ where $$P_{n+1} = P_n + \frac{b-P_n}{2}$$ $$P_0 = a$$ and $a,b \in \mathbb{R}$ such that $a&gt;b$ My proof goes as follows:   We must prove that $$\lim_{n\to\infty}P_n=b$$  That is, $\forall\epsilon&gt;0$ there exists a $\delta$ such that there exists an $n$ satisfying $$n&gt;\delta \iff b-P_n&lt;\epsilon$$  First, let us prove that $P_n$ is bounded by $b$ by contradiction. Let us choose an $i$ such that $P_i &lt; b$ and $P_{i+1}&gt;b$. Then we have $P_{i+1} = P_i + \Delta P$ where $\Delta P &gt; b-P_i$. but this is impossible because by the definition of the recurrence $\Delta P = \frac{b-P_i}{2} &lt; b-P_i$. Therefore, $P_i$ is bounded from above by $b$.  Additionally, it is trivial to show that $P_{i+1} &gt; P_i$.  With this in mind, choose an arbitrary $\epsilon$. We need to show that there exists an $n$ such that $P_n &gt; b-\epsilon$. Assume the contrary, that $P_n$ is bounded by $\epsilon$.  Using a similar argument to what which was used before, assume $P_n$ is bounded by $\epsilon$ and then there exists a $P_i$ such that $P_{i+1}\not &gt; P_i$. But this results in a contradiction with (4)  Therefore, $P_n$ is not bounded by $\epsilon$ and we have proved what we want to prove. Flash plugin up to date but Firefox keeps telling me that I have the old version XPath select node with namespace Values of $\sum_{n=0}^\infty x^n$ and $\sum_{n=0}^N x^n$ Why can't I find a USB-C hub with multiple USB-C ports? My computer only has one USB-C port and I want to connect multiple USB-C devices to it.  I have trawled through Amazon but am amazed that I cannot find a single one. There are many hubs that have USB 3.1 USB-A ports but not USB-C ones.  Is there a limitation in the spec that prevents this being possible? Backup with duplicity on Google Cloud Storage I have already set a backup routine that backups all my files to Amazon S3 using duplicity. I would like to create a similar backup routine with Google Cloud Storage. Is it possible to get duplicity to work with GCS? Use of substitution into the integral $\int_0^2 \frac{\arctan x}{x^2+2x+2}dx$ This question: got some attention, but I didn't understand anything of it. Now I looked at the solution of the book and there is given the hint to use the change of variable $$x=\frac{1-t}{1+2t}$$ Could you please explain how one could think of such substitution? Is there some intuition behind this? Also after I used the substitution I got: $$\int_{-1/5}^1\frac{3\arctan\left(\frac{1-t}{1+2t}\right)}{5t^2+8t+5}dt$$ How can I finish this using the hint from the book? Wubi with 14.10 doesn't work - failed to partition the selected disk I tried to install Ubuntu 14.10 on my computer with Wubi. The installation appeared to work in Windows, and told me to reboot.   After rebooting the Ubuntu installer continued the installation, until it stopped with an error message: Failed to partition the selected disk with the detail This probably happened because are too many primary partitions in the partition table.