how to find The letter with the most frequency in the user input
How do I count the number of occurrences of a char in a String?
\overline outside of math mode If I want to draw an overline over some text, not an equation, how can I do it? \overline seems to only work in math mode, and when used outside of math mode, it automatically says "Missing $ inserted". 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? Suppose $X,Y$ and $Z$ are multivariate normal with means and full covariance matrix. The conditional expectation $E(X | Y)$ is well know. What is the conditional expectation of $E(X | Y,Z)$ if $Y$ and $Z$ (and $X$) are correlated? Standard textbooks only seem to cover the case when $Y$ and $Z$ are uncorrelated. Is it possible to know the (public) IP address of a computer where TeamViewer is ready for a remote control session - without connecting to the computer? I have read that a holomorphic function in an open disc has a primitive in that disc. Does this mean that for any holomorphic function $f$ in any open set $U,$ that $f$ has a primitive? I say this because I can take a large enough open disc to cover the open set $U$ and find its primitive there. Is this a correct way of thinking? Javascript && operator as if statement? Once and for all: Is there anything that can possibly be done to my commander that would cause it to cease being my commander?    All of these questions ask the same thing, but aren't general enough to be marked as a duplicate.      Is a commander still a commander if it gets turned into a forest?     Is a commander still a commander if it gets turned face down? How to upload a file of size 2GB from Apex? Is there any sobject that I can make use of? How to programmatically click a button in WPF? How is arccos derived? Stupid question but I need to understand:  If $ \cos = \dfrac{\text{adjacent}}{\text{hypotenuse}} $  What is arcosine? $ \text{adjacent} \cdot \text{hypotenuse}$? Is this the same for arcsine and arctangent? Currently, Stack Exchange’s Markdown parser only allows four-space indents to represent code blocks:      // some code     // another line of code    and other Markdown implementations allow for an alternative syntax, that doesn’t require indenting each code line:  ``` // some code // another line of code ```   This is much more convenient to type out. It would be super useful if Stack Exchange could support this syntax.    By extension, this syntax also allow you to specify the source language right after the opening ```:  ```js // some code // another line of code ```   …which would then enable syntax highlighting for that specific language. Although it’s interesting metadata, I don’t think this feature is needed on Stack Overflow, as the syntax highlighting library works pretty well for various languages.  So, even if you would allow this syntax but ignore the ```language, this would greatly improve my productivity on Stack Exchange.  What do you think?  The moderators are currently collecting feedback regarding this feature, so please post a comment with your thoughts. Good idea? Bad idea? Don’t really care? What do you think are the benefits/drawbacks? Experiences? Let them know! Thanks! How to carry cologne bottles in hand luggage and prevent losses? Why are the dineutron and diproton unbound? At college we use ArcGIS Desktop 10, but that does not function on my Mac so I have QGIS there instead.  I want to do my exercises with QGIS, but in ArcGIS Desktop we use .lyr files with ArcMap and .lyrx files with ArcGIS Pro, and they are not supported by QGIS.  Does anyone know, how I can connect the *.lyr files to my *.shp files to use them on my Mac with QGIS? Why does increasing the number of features reduce performance? How do I create a PPA? How do I create my own custom PPA to share with the Ubuntu community? I am trying to create my own custom package set and I would really like to share it with the community. How do I get add-apt-repository to work through a proxy? reconfiguration issues with dpkg I ran into some problems installing a package with apt. The terminal hung up during an install and I saw no other choice but to close the terminal. The problem, however, is that I can't seem to solve the issues that this has caused.   As is typical, I get:  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   This gets me nowhere and I'm locked out until I run sudo dpkg --configure -a. Makes sense. However, this process spits the following out and then hangs on the last line:  Setting up virtualbox-dkms (5.2.10-dfsg-6) ... Removing old virtualbox-5.2.10 DKMS files...  -------- Uninstall Beginning -------- Module:  virtualbox Version: 5.2.10 Kernel:  4.15.0-23-generic (x86_64) -------------------------------------  Status: This module version was INACTIVE for this kernel. depmod...  DKMS: uninstall completed.  ------------------------------ Deleting module version: 5.2.10 completely from the DKMS tree. ------------------------------ Done. Loading new virtualbox-5.2.10 DKMS files... Building for 4.15.0-23-generic Building initial module for 4.15.0-23-generic   A typical solution I've read is that you need to fix the broken packages. When I try to fix the broken packages (sudo apt install -f), the system also hangs on the same line, although the output is different:  Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 3 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Setting up virtualbox-dkms (5.2.10-dfsg-6) ... Removing old virtualbox-5.2.1  0 DKMS files...  ------------------------------ Deleting module version: 5.2.10 completely from the DKMS tree. ------------------------------ Done. Loading new virtualbox-5.2.10 DKMS files... Building for 4.15.0-23-generic Building initial module for 4.15.0-23-generic   I am unable to get out of it unless I kill the process. This I do by checking what is currently running related to apt (ps aux |grep apt), and then I kill the relevant processes with sudo kill -9 process_number_here.  If I try to run things after that, it tells me I still need to reconfigure dpkg.  I tried looking around for more solutions to dpkg and all I really see is the nuclear option:  sudo rm /var/lib/dpkg/lock sudo rm /var/cache/apt/archives/lock sudo rm /var/lib/apt/lists/lock   I also delete the files in /var/lib/dpkg/updates because when I did some digging one of the files inside had the exact same text as the above long output... but I fully admit to being out of my league here and I don't know what to do.   Taking a look at the error messages, I recognize that it hangs on building something related to the kernel. But I have no idea where to even start solving that. Any help is appreciated. My system is ubuntu 18.04 Initialize parameter of method with default value Convergence of the series $\sum a_n$ implies the convergence of $\sum \frac{\sqrt a_n}{n}$, if $a_n>0$ I need help to solve following problem from Rudin's Mathematical analysis book:    Convergence of the series $\sum a_n$  implies the convergence of $\sum \dfrac{\sqrt {a_n}}{n}$, if $a_n&gt;0$  I tried to construct a suitable convergence sequence $b_n$ such that $\sum b_n$ converges and $a_n \leq b_n$ but, I am not able to find such sequence $b_n$ .  Thanks for the help and sugestions.