Disable gnome from asking passphrase in GUI when using ssh and gpg from terminal
How to disable the keyring for SSH and GPG?
Reflection of sound waves from the open end of an organ pipe & relationship b/w nodes & pressure We know that standing waves are created when any wave traveling along the medium will reflect back when they reach the end. But in an open organ pipe, there is nothing to oppose the wave and reflect it back. So then how are standing waves created in such a case? In standing waves where is the pressure greater, at nodes or anti-nodes? What are the differences between a bridge camera and a DSLR? Inserting the value from Datetime field form I have a form where the user can input datetime and then I want to store it in the database. Here's my schema :     'start' => array(           'type' => 'varchar', 'mysql_type' => 'datetime',           'not null' => FALSE,         ),   The form :     $form['add']['start'] = array(         '#type' => 'datetime',   '#default_value' => $date,       );   When I hit submit button, it shows me :     db_insert failed. Message = SQLSTATE[22007]: Invalid datetime format: 1292 Incorrect datetime value:...   What I got out of it was that the DateTime in Drupal is incompatible with MySQL's. Any suggestions or how should I process the value from the form so I can insert it into the db?  Alternatively, any way to convert DrupalDatetime into string?  (For what it's worth I also tried 'timestamp' as the MySQL type but it throws me the same error). What is a word that means to say in a positive sense? For instance, when writers say that a person was sexually assaulted instead of saying raped.  Or people use let go instead of fired.  What is that called? Does the following series have a closed-form expression:  $$\sum_{k=0}^{\infty} \frac{z^k}{(k!)^2}$$  I know that it must converge because:  $$\sum_{k=0}^{\infty} \frac{z^k}{k!} = e^z$$  and the $(k!)^2$ denominator obviously increases more quickly than the $k!$ denominator.  This problem came up in computing the probability of a draw in a football match with each team's goal scoring modeled as a Poisson process.  Thanks,  John Given   $$ f_{XY}(x,y) = \frac{1}{2\pi \sqrt{1-\rho^2}} \exp \left( -\frac{x^2 +y^2 - 2\rho xy}{2(1-\rho^2)} \right) $$  $Y = Z\sqrt{1-\rho^2} + \rho X$  And   $$ f_{XZ}(x,z) = \frac{1}{2\pi } \exp \left( -\frac{x^2 +z^2}{2} \right) $$  Show that $P(X&gt;0,Y&gt;0)= \frac{1}{4}+\frac{1}{2\pi}(\arcsin \rho) $  I'm supposed to use the fact that X and Z are independent standard normal random variables, but I don't quite understand how. Any help would be greatly appreciated. How to convert a one digit number to a two digit number I have a table that represents a timetable for bus, so each cell contains time of departure as hour followed by minute, both as two digits, but sometimes I don't have two digits,just one so I have to switch eg. from 12 4 -&gt; 12 04. How is it possible? Can Reduce *really* not solve for x here? I saw there are various manga with Akame ga KILL! in their names.  The ones I have found are:       Which one should I read if I want to continue the storyline of the anime? I was asked this question in an interview.  Lets say we have a correlation matrix of the form \begin{bmatrix}1&amp;0.6&amp;0.8\\0.6&amp;1&amp;\gamma\\0.8&amp;\gamma&amp;1\end{bmatrix}  I was asked to find the value of gamma, given this correlation matrix. I thought I could do something with the eigenvalues, since they should be all greater than or equal to 0.(Matrix should be positive semidefinite) - but I don't think this approach will yield the answer. I am missing a trick.  Could you please provide a hint to solve for the same? How can I prevent spam on sites which I control? This is a general, community wiki question to address all non-specific spam prevention questions.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .    For purposes of this question, spam will include:   Any automated post Manually-posted content which includes links to spammers' sites Manually-posted content which includes instructions to visit a spammer's site vi shows as vim When I type vi into a terminal it shows the following display:    Note that it says vim not vi, I'm sure I haven't downloaded vim yet and that this is actually vi not vim: for example the arrow keys print ABCD instead of moving. Why can partial derivatives be exchanged? In the   post in this stack exchange, one of the answers to the questions of do partial derivatives commute is: Second order partial derivatives commute if f is $C^2$ (i.e. all the second partial derivatives exist and are continuous). This is sometimes called Schwarz's Theorem or Clairaut's Theorem. This theorem is in my textbooks, yet I cannot seem to find the proof in them. I have tried proving the theorem yet I have gotten stuck. So, what is the proof of Clairaut's Theorem, or why do partial derivatives commute? If the proof is too long, a link to the proof with an intuitive explanation will be sufficient. how to prove that $\ln(1+x)< x$ gedit "cannot open display" , on remote computer , using ssh - Ubuntu 12.04 Possible Duplicate:          I am getting the following error message when using ssh to log into a remote machine:      gedit: cannot open display   I am using ssh in - Ubuntu 12.04. How do I rigorously show $f(z)$ is analytic if and only if $\overline{f(\bar{z})}$ is? I'm doing a bit of self study, but I'm uncomfortable with a certain idea. I want to show that $f(z)$ is analytic if and only if $\overline{f(\bar{z})}$ is analytic, and by analytic I mean differentiable at each point. Here $f$ is a complex valued function.  What I do is write $f(z)=u(x,y)+iv(x,y)$, where $u$ and $v$ are real functions of two variables. Then $\overline{f(\bar{z})}=u(x,-y)-iv(x,-y)$.  These two forms look very similar, in the sense the one function being differentiable should immediately imply the other is differentiable, since the only thing really changing might be a $-$ sign popping out due to the chain rule.   How can I more rigorously express that $f(z)$ is analytic iff $\overline{f(\bar{z})}$ using this? Many thanks. How to apply standardization/normalization to train- and testset if prediction is the goal? I want to be able to calculate the confidence interval from the estimated coefficient and respective standard errors.  I have a linear regression model which can be summarized (in R):  summary(fit1)  Call: lm(formula = bwt ~ height + weight + parity, data = data)  Residuals:     Min      1Q  Median      3Q     Max  -66.913 -10.624   0.991  10.979  55.621   Coefficients:             Estimate Std. Error t value Pr(&gt;|t|)     (Intercept) 31.19217   13.56879   2.299   0.0217 *   height       1.24964    0.23083   5.414 7.48e-08 *** weight       0.06781    0.02823   2.402   0.0164 *   parity1     -1.83309    1.19838  -1.530   0.1264     --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  Residual standard error: 17.9 on 1170 degrees of freedom Multiple R-squared:  0.04898,   Adjusted R-squared:  0.04654  F-statistic: 20.08 on 3 and 1170 DF,  p-value: 1.071e-12   With this model I can calculate the respective confidence intervals:  &gt; confint(fit1)                   2.5 %     97.5 % (Intercept)  4.57029503 57.8140351 height       0.79676227  1.7025207 weight       0.01243198  0.1231932 parity1     -4.18429933  0.5181151   I would expect the intervals of the predictor height to be given by  $$ 1.24964 \pm (1.96*0.23083) = [0.7972132,1.702067] $$  where 1.24964 is the estimated value for the coefficient and 0.23083 is the standard error for this coefficient. The numbers are close but not quite the same.  What am I doing wrong? How do I cherry pick packages from a PPA? I am planning an hour and a half ride with my 1 month old baby girl. I heard that being in the car seat for a long time is not good for newborns.  Is an hour and a half too long? Should we do a stop in the middle of the trip?