What three odd integers have a sum of 30?
What five odd integers have a sum of $30$?
I used to study at Cambridge School I used to study at Cambridge School.  I am used to studying at Cambridge School.  If the verb is continuous tense, it need to be added "verb to be" before used to? SQLite - UPSERT *not* INSERT or REPLACE Is there some clever way to do this in SQLite that I have not thought of? Basically I want to update three out of four columns if the record exists, If it does not exists I want to INSERT the record with the default (NUL) value for the fourth column. The ID is a primary key so there will only ever be one record to UPSERT. (I am trying to avoid the overhead of SELECT in order to determine if I need to UPDATE or INSERT obviously) Suggestions?  I cannot confirm that Syntax on the SQLite site for TABLE CREATE. I have not built a demo to test it, but it doesn't seem to be supported. If it was, I have three columns so it would actually look like: CREATE TABLE table1(      id INTEGER PRIMARY KEY ON CONFLICT REPLACE,      Blob1 BLOB ON CONFLICT REPLACE,      Blob2 BLOB ON CONFLICT REPLACE,      Blob3 BLOB  );  but the first two blobs will not cause a conflict, only the ID would So I assume Blob1 and Blob2 would not be replaced (as desired)  UPDATEs in SQLite when binding data are a complete transaction, meaning Each sent row to be updated requires:  Prepare/Bind/Step/Finalize statements unlike the INSERT which allows the use of the reset function The life of a statement object goes something like this:  Create the object using sqlite3_prepare_v2() Bind values to host parameters using sqlite3_bind_ interfaces. Run the SQL by calling sqlite3_step() Reset the statement using sqlite3_reset() then go back to step 2 and repeat. Destroy the statement object using sqlite3_finalize().  UPDATE I am guessing is slow compared to INSERT, but how does it compare to SELECT using the Primary key? Perhaps I should use the select to read the 4th column (Blob3) and then use REPLACE to write a new record blending the original 4th Column with the new data for the first 3 columns? Can we prevent titles with an unnecessary tag in them? So we have lots of questions that are titled like this:  Specifically, questions that have one of their tags in front of their title. Thankfully, these silly users usually use a hyphen or a colon afterwards, which makes it really easy to . Can we clear up this clutter?  Perhaps with a filter that strips off the excess when posting? EDIT: As an added bonus, see  for another style of question title that bugs the heck out of me. How do I make a bootable Ubuntu USB? How do I make an Bootable Ubuntu USB containing the the latest version of Ubuntu?  For completeness, how would I be able to do this on Ubuntu, Windows, OS X or another Linux distro? Images are escaping from the help center privilege page Images included in the fully expanded privilege pages are escaping from the body.    This is most noticeable on the  (which I know is going away soon anyway):    But is also apparent on:       In the edit page preview, the images sit correctly within the borders.  Chrome 27, Windows 7 In my custom Drupal 8 plug-in I perform such query:  $select = db_select('my_table', 'e'); $select-&gt;addField('e', 'field1');  $select-&gt;condition('field3', 'NULL', '!='); $select-&gt;condition('field4', array(11, 12, 31, 32, 33), 'IN');  $select-&gt;groupBy("e.field1"); $select-&gt;orderBy("e.field1"); $select-&gt;orderBy("e.field5"); $entries = $select-&gt;execute()-&gt;fetchAll(\PDO::FETCH_ASSOC);    And it works fine. It returns me all records grouped by field1 that meets the condition, orderered. But it returns only field1 column.  I wanted to get more columns, so I have added another $select-&gt;addField('e', 'field2'); just after first one:  $select = db_select('my_table', 'e'); $select-&gt;addField('e', 'field1'); $select-&gt;addField('e', 'field2');  $select-&gt;condition('field3', 'NULL', '!='); $select-&gt;condition('field4', array(11, 12, 31, 32, 33), 'IN');  $select-&gt;groupBy("e.field1"); $select-&gt;orderBy("e.field1"); $select-&gt;orderBy("e.field5"); $entries = $select-&gt;execute()-&gt;fetchAll(\PDO::FETCH_ASSOC);    This time I get error:     Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[42000]: Syntax error or access violation: 1055 Użyto 'my_database.e.field2' bez umieszczenia w group by:   Which means "my_database.e.field2 has been used without putting in into group by". But I don't want to group by every column I select.  Unfortunatelly Drupal 8 added ONLY_FULL_GROUP_BY :( Then, how can I use groupBy and select more then one column at the same time? Why would Antimatter behave differently via Gravity? Prove that $f$ is differentiable Summarize the mathematical problem at the heart of breaking a Curve25519 public key It's pretty easy to generate a Curve25519 private key: generate 32 random bytes of data and then do:  e[0] &amp;= 248 e[31] &amp;= 127 e[31] |= 64   You can then generate a public key by doing  on the private key. For example, here's a random keypair I just generated:  public: e40ed268dff20db8497d0691421d00b086aad1efedcd5bd223d9eb6c0b85665f secret: e3c0e8b20ba7894882ddb37522dbe90867befcf9f31a5ce29c0d7997e0bd856d   The whole safety of public key encryption is that it is hard to take a public key and reverse the operation. Elliptic curve cryptography, as I understand it, relies on the fact that a  is hard to find. In particular, for a given large b and g, it is hard to find an integer k such that  $b^k = g$  How does that equation relate to Curve25519? Specifically, if I had a public key like the one above, how would I express, in math terms, the problem I need to solve to find the private key? How does it relate to the equation I see from time to time - $y^2 = x^3+486662x^2+x$, and the number $2^{255} - 19$?  I am guessing it is not as simple as "the private key is k and the public key is b and/or g" in the equation above. I'm also a little confused because the keys would appear to have roughly the same number of digits, which would seem to imply that there aren't many feasible values for k? Can't format my usb drive. I have already tried with mkdosfs and gparted I have a MicroSD card in a USB adapter (which plugs into a USB port on my machine, and acts like a USB flash drive). I was using Unetbootin to make this a bootable USB flash drive with Kubuntu. But I needed to cancel while it was working. So I killed the Unetbootin process from the console.  Since then, I can't format the MicroSD or delete the folder that Kubuntu made. I have also tried mkdosfs, with no success. I can't mount the drive anymore either? What can I do to make this drive usable again?  Trying to create a new partition table in GParted, as described in Eliah Kagan's answer, does not work. It fails with the error message "imposible crear tabla de particiones" ("unable to create a partition table"). Are there any clones/alternatives for running a Stack Exchange style Q&A site? Simulating data to fit a mediation model I am interested in finding a procedure to simulate data that are consistent with a specified mediation model.  According to the general linear structural equation model framework for testing mediation models first outlined by  and described elsewhere such as , mediation models for outcome $Y$, mediator $\newcommand{\med}{\rm med} \med$, and predictor $X$ and are governed by the following three regression equations: \begin{align} Y    &amp;= b_{11} + b_{12}X + e_1                \tag{1}  \\ \med &amp;= b_{21} + b_{22}X + e_2                \tag{2}  \\ Y    &amp;= b_{31} + b_{32}X + b_{32} \med + e_3  \tag{3} \end{align} The indirect effect or mediation effect of $X$ on $Y$ through $\med$ can either be defined as $b_{22}b_{32}$ or, equivalently, as $b_{12}-b_{32}$.  Under the old framework of testing for mediation, mediation was established by testing $b_{12}$ in equation 1, $b_{22}$ in equation 2, and $b_{32}$ in equation 3.  So far, I have attempted to simulate values of $\med$ and $Y$ that are consistent with values of the various regression coefficients using rnorm in R, such as the code below:  x   &lt;- rep(c(-.5, .5), 50) med &lt;- 4 + .7 * x + rnorm(100, sd = 1)   # Check the relationship between x and med mod &lt;- lm(med ~ x) summary(mod)  y &lt;- 2.5 + 0 * x + .4 * med + rnorm(100, sd = 1)  # Check the relationships between x, med, and y mod &lt;- lm(y ~ x + med) summary(mod)  # Check the relationship between x and y -- not present mod &lt;- lm(y ~ x) summary(mod)   However, it seems that sequentially generating $\med$ and $Y$ using equations 2 and 3 is not enough, since I am left with no relationship between $X$ and $Y$ in regression equation 1 (which models a simple bivariate relationship between $X$ and $Y$) using this approach.  This is important because one definition of the indirect (i.e., mediation) effect is $b_{12}-b_{32}$, as I describe above.  Can anyone help me find a procedure in R to generate variables $X$, $\med$, and $Y$ that satisfy constraints that I set using equations 1, 2, and 3? Where can I find sample or real Selenium projects. All the material I can find on github and on internet are basic, and never intermediate or advanced.  How does a real Selenium project look in real life? How can I find sample code? What do I set the 'Opens with...' property to in order to get the system to run .bat files again (when they are double-clicked)?  Somehow my boss convinced his workstation that the handler for .bat files was supposed to be Word. Now, when double-clicking .bat files, they're opened up in Word. "This is a favorite question" tooltip when not favorite Understanding English (Listening skills) I always know that the natural logarithm $\log_e$ is the inverse of the exponential function $e$, but to my surprise when reading elementary functions in complex analysis, I discover that that is not always true. $$\log(e^z)=z+2k\pi i$$  My question here is that, why is the above expression true? How do single photons travel from here to there I know there have been similar questions but I'm still unclear what the overall consensus is. (1) I assumed and have read that photons travel in straight lines unless deflected by gravity but there are conflicting theories. (2) I have heard that single photons takes every possible path but that makes no sense. Why would a single photon traveling from here to the moon go to every other place in the universe along the way.  (3) I can understand a single photon traveling as a particle or packet of energy but I have a hard time understanding a single photon traveling as a wave. I have never understood any attempts to answer this.  (4) Does a single photon have a frequency and what causes the frequency? If not then how does it have energy? I have many questions about single photons and their frequency. Where can I get a device with 'Ubuntu for phones' pre-installed? Comparing $\pi^e$ and $e^\pi$ without calculating them How can I  compare (without calculator or similar device) the values of $\pi^e$ and $e^\pi$ ?