How to start an official email to a professor
How should I phrase an important question that I need to ask a professor?
I am looking for an adjective, similar to "holding a grudge" I am looking for an adjective that describes a person who is not willing to forgive or excuse someone's faults or wrong-doings from the past (other than "unforgiving"). For the ones who speak German, that word would be "nachtragend". Easy way to concatenate two byte arrays Replace a string in a text file using a shell script not working properly I have a text file containing this:  0 0 -1 0 1 0 0 0 0 -1 0 0 1.5 0.0 1.0 1   and I want to replace the 1.0 to 2.0 so that it becomes:  0 0 -1 0 1 0 0 0 0 -1 0 0 1.5 0.0 2.0 1   so I use this command:  sed -i 's/'1.0'/'2.0'/g' /home/user1/file1.txt   or this:  sed -i 's/1.0/2.0/g' /home/user1/file1.txt   but this is the result that appears and I don't know how to fix this:  0 0 -2.0 2.0 0 0 0 -2.0 0 1.5 0.0 2.0 1 proving topological equivalence How would I show that $$d_E = \sqrt{\sum_{i=1}^n(x_i-y_i)^2}$$ and $$d_\infty= \sum_{i=1}^n|x_i-y_i|$$ and $$\sup\{|x_1-y_1|,|x_2-y_2|,...,|x_n-y_n|\}$$ are topologically equivalent on $\mathbb{R}^n$? I can do it for $\mathbb{R}^2$, but I'm not sure how a generalization looks like. Is there a command prompt  equivalent for Windows 7? That is, I want to filter out the results of a command:  Bash use:  ls | grep root  What would it be from a Windows command prompt? The difference between log and ln $$\dfrac{1}{2}\ln(x+7)-(2 \ln x+3 \ln y)$$  Our professor let's us solve this but i do not understand how $\ln$ works. He says it has same properties with $\log$ but i still don't get it. What's the difference of the two? What should I do after a suspected compromisation of my system? Multiple File Extension Rename with single command I received some important files via mail. There are about 150 files like these. The extensions of the files are named as zip1,zip2,zip3, zip_ etc. I just want to change the extension of these files back to zip using a single command to avoid the manual task of renaming each file. Significant predictors become non-significant in multiple logistic regression When I analyze my variables in two separate (univariate) logistic regression models, I get the following:  Predictor 1:    B= 1.049,    SE=.352,    Exp(B)=2.85,    95% CI=(1.43, 5.69),    p=.003    Constant:    B=-0.434,    SE=.217,    Exp(B)=0.65,                            p=.046  Predictor 2:    B= 1.379,    SE=.386,    Exp(B)=3.97,    95% CI=(1.86, 8.47),    p&lt;.001    Constant:    B=-0.447,    SE=.205,    Exp(B)=0.64,                            p=.029   but when I enter them into a single multiple logistic regression model, I get:  Predictor 1:    B= 0.556,    SE=.406,    Exp(B)=1.74,    95% CI=(0.79, 3.86),    p=.171 Predictor 2:    B= 1.094,    SE=.436,    Exp(B)=2.99,    95% CI=(1.27, 7.02),    p=.012    Constant:    B=-0.574,    SE=.227,    Exp(B)=0.56,                            p=.012   Both predictors are dichotomous (categorical). I have checked for multicollinearity.  I am not sure if I have given enough info, but I cannot understand why predictor 1 has gone from being significant to non-significant and why the odds ratios are so different in the multiple regression model. Can anyone provide a basic explanation of what is going on? Implementing INotifyPropertyChanged - does a better way exist? When the phrase is used as an object, why so many native speakers are saying "you and I" instead of "you and me"? I'm not a native speaker but I thought "you and me" is correct. Not sure if this falls into the same category, but "Just between you and me" sounds more natural than "Just between you and I". setting upper and lower limits in rnorm Why was my flag declined? I've recently flagged the following , which I got in the flag queue.   The answer does not seem to attempt to address the question at all. It looks like a comment on one of the other answers (probably Luca's).  It got rejected with the following reason:  declined - flags should not be used to indicate technical inaccuracies,            or an altogether wrong answer   I did not flag this because I thought it was wrong, I flagged it because I didn't think it was an attempt to answer the question. For what it's worth, I don't get what the guy who provided that answer even tried to say.  Was I wrong to flag it? If so why? What is the difference between char * const and const char *? How was Hedwig able to find Sirius? In the beginning of Goblet of Fire, Harry sends Snuffles a letter.  Hedwig somehow finds him after the extremely specific command from Harry, "Just find him, okay?"   Theories:   Hedwig has a scanning system, like Baymax in Big Hero 6. Hedwig got super lucky. Hedwig flies really, really fast.   Now I know that owls are intelligent beings in the Harry Potter canon. But.... those ideas are just as crazy as the next.  So how did Hedwig do it? Request of a domain with no virtualhost in apache ends to default virtualhost If I ask Apache for domain.com that has no Virtual Host setup in Apache configuration, Apache will show the default Virtual Host. How can I prevent this from happening or simply drop the connection? I currently have Windows 7 on my computer and I want to install Ubuntu alongside Windows safely.  Could someone please provide clear instructions? How to embed Stack Overflow flair in a WordPress.com (free) blog? Has anyone successfully embedded their  on a WordPress.com-hosted blog?  The free hosted version of  (not )  from all posts before publishing. So they to strip out just about anything I can add to embed my Stack Overflow flair.  Note: I'll be switching to a paid, hosted site in the future (fixing the problem), but I'm looking for a quick, short-term solution. Schengen Business visa without a business invitation letter $y'=$ ${-x+\sqrt{(x^2+4y)}}\over 2$ , $y(2)=-1$ Prove that the solutions $y_1$ and $y_2$ for the initial value problem   $y'=$${-x+\sqrt{(x^2+4y)}}\over 2$ , $y(2)=-1$  are:  $y_1=1-x$  $y_2={{-x^2}\over 4}$  And explain why the two solutions not contradiction with the theory of existence and uniqueness.  ( sorry I don't speak English well )  My answer:  For the initial condition :  $y_1=1-x$ Satisfy the initial condition  $y(2)=-1$  $y_1=1-2=-1$   And Satisfy the differential equation  ${y_1}^{\prime}=-1$  ${{-x+\sqrt{x^2+4y}}\over 2}={{-x+\sqrt{x^2+4(1-x)}}\over 2}$  $={{-x+\sqrt{(x-2)^2}}\over 2}$  $={{-x+x-2}\over 2}=-1$  L.h.s.=R.h.s.  $y^{\prime}={{-x+\sqrt{x^2+4y}}\over 2}$  Also $y_2$ Satisfy the initial condition  $y_2={{-x^2}\over4}={-4\over4}=-1$   And satisfy the differential equation.   $y_2^{\prime}={-x\over 2}$  ${{-x+\sqrt{x^2+4y}}\over 2}={{-x+\sqrt{x^2+4({-x^2\over 4})}}\over 2}={-x\over 2}$  And for second part of exercise:  ${\partial f\over \partial y}={1\over \sqrt{x^2+4y}}$  and this not defined when $x=2, \ y=-1$  So $f(x,y)$ no satisfy lipshtize condition in any rectangular has (2,-1), Lipshtize condition including uniqueness of solution, so no contradict with the existence and uniqueness.  True ?  If this also wrong I well be delet it , I answered by the same way of my teacher :(