"I can't write on file ..." when installing class from a .ins file I'm trying to install the elsarticle class manually on MiKTeX 2.9 (Windows) from the .ins file. However, when I type latex .\elsarticle.ins, I get the following:  This is pdfTeX, Version 3.14159265-2.6-1.40.17 (MiKTeX 2.9) entering extended mode ! I can't write on file `elsarticle.log'. Please type another transcript file name:   When I type any other file name, I keep getting the same error.
How can I install a package on MikTeX? I need to install a LaTeX package on my MikTeX system.  Specifically, I am trying to make biblatex work, but I always get the error message:    ! LaTeX Error: File `biblatex.sty' not found.   I have changed the options to have the "Quick Build" command that includes biblatex too.   Code/commands are correct because it's working under Overleaf.
Performance differences between pipelines and process substitution I tend to use pipelines in my bash scripts over process substitution in most situations, especially in cases of using multiple sets of commands as it seems more readable to do ... | ... | ... over ... &lt; &lt;(... &lt; &lt;(...)).  I'm wondering though why using process substitution is much faster in some situations than using a pipeline.  To test this, I timed two scripts using 10000 iterations of the same attached commands with one using a pipeline and another using process substitution.  Scripts:  pipeline.bash:  for i in {1..10000}; do     echo foo bar |     while read; do         echo $REPLY &gt;/dev/null     done done   proc-sub.bash  for i in {1..10000}; do     while read; do         echo $REPLY &gt;/dev/null     done &lt; &lt;(echo foo bar) done   Results:  ~$ time ./pipeline.bash  real    0m17.678s user    0m14.666s sys     0m14.807s  ~$ time ./proc-sub.bash  real    0m8.479s user    0m4.649s sys     0m6.358s   I know that pipelines create a sub process whereas process substitution creates a named pipe or some file in /dev/fd, but am unclear about how those differences impact performance. Simulation software to solve high school level mechanics problems I'm a physics teacher and I would like to find a simulation software that could be used to give exact numerical answers to high school level problems in Newtonian mechanics.  I want the students to first calcultate a numerical answer to a physics problem and then use the simulator to visualize the problem in order to understand it better and verify that the simlator gives the same answer that they got when doing the calculation themselves.  Here are some examples of what kind of problems I want the students to be able to solve with the simulator:   A slope with a specific angle of inclination and a ball starts rolling at a certain point. Determine the speed, angular momentum and total mechanical energy of the ball after a specific time t. A ladder of known mass and length is leaning against the wall at a specific angle. The contact between the ladder and the wall is frictionless. Calcultate the x and y components of the force between the floor and the ladder.   I would like the software to have the following features:  - Simulation in 2D. No 3D simulations are necessary and the software should at least have the option of doing simulations only in 2D.  - Position all objects exactly by writing numbers (just positioning the objects using the mouse is not precise enough).  - Show animations of the time evolution of the system.  - Show forces, velocities and accelerations as arrows.  - Give exact numerical results so that the students can use the software to verify their calculation.  Ideally the software would have a graphical user interface, but if no suitable software with graphical interface exixts, I could also consider a software with text-based inputs. I would consider both free and commercial software.  My question is: Is there any software that would meet these requirements and if there is, where could I get it? Any smart ideas on finding the area of this shaded region? Is it possible for test error to be lower than training error Is it possible to have test error lower than training error?  I have a classification problem with 2000 samples, 500 of which are positives, 1500 are negatives. I split my data into 70% training data, 30% test data.  Run random forest with 200 estimators and cv=10. I did this several times and compared the recall and precision score and notice the scores for my test set is significantly better. Is this possible? Difference between "asked" and "were to ask" in conditional sentences? How can I search an Excel spreadsheet in SharePoint? Looking to be able to search an Excel spreadsheet from the SharePoint mobile app.  I have a spreadsheet with Postal Codes/Zip Codes with corresponding information. I would like to be able to search as you would in Excel.  When I upload a test spreadsheet, it opens as like a PDF. User has "Read" permissions for the document library the spreadsheet is located in.  Thanks in advance, How to peel hard boiled eggs easily? This is one of the most annoying duties in the kitchen, for me.  What are yours tips and tricks to peel hard boiled eggs easily? How can I run a program on startup, minimized? I just want Telegram to be run and I have added it to startup apps. The point is that I need it to be minimized. Any commands? (Sorry to re-post this, I have lost access to my original account.)  I've recently installed Kubuntu 18.04.3 on a new AMD Ryzen 3000-series-based system. The system is installed on a SATA SSD, specifically on an Ext4 partition, with a SATA HDD formatted in NTFS mounted for storage. The system has been in use for a few days, with a maximum uptime of two days (so far).  My issue is this: the HDD indicator light on the case flashes every 1-3 seconds, even when the system is idle, and there is no obvious reason to access the disk. The flashes are not regular: sometimes the light is dark for as long as 3 seconds (obviously it is difficult to time such short intervals -- I am approximating), sometimes there are a few quick pulses less than a second apart. The flashes seem to vary in duration as well -- sometimes very brief, sometimes nearly a second. Unmounting the secondary HDD does not appear to have any effect.  Some searching lead me to try iotop. I ran sudo iotop -Pao, and waited until 10 flashes of the HDD light had occurred. This is the result:   6887 be/4 root          0.00 B      0.00 B  0.00 %  0.02 % [kworker/u64:1-events_power_efficient]   433 be/3 root          0.00 B      0.00 B  0.00 %  0.02 % [jbd2/sda2-8]  6302 be/4 root          0.00 B      0.00 B  0.00 %  0.01 % [kworker/u64:0-events_unbound]   The "kworker" processes seem to switch between various states, such as "events_power_efficient", "events_unbound", and "events_freezable_power_". The jdb2 process does sometimes write to disk, though that was not observed here (even though, as I said, 10 flashes of the HDD light occurred). The computer was otherwise idle during this test.  My searches also lead me to check /var/log. The result of ls -lth | head is as follows:  -rw-r-----  1 syslog adm             951K Aug 27 19:49 kern.log -rw-r-----  1 syslog adm             594K Aug 27 19:49 syslog -rw-r-----  1 syslog adm             528K Aug 27 19:49 ufw.log -rw-r-----  1 syslog adm              53K Aug 27 19:48 auth.log -rw-r--r--  1 root   root             40K Aug 27 19:15 Xorg.0.log -rw-rw-r--  1 root   utmp             79K Aug 27 18:29 wtmp -rw-r--r--  1 root   root              55 Aug 27 16:28 prime-offload.log -rw-r--r--  1 root   root              30 Aug 27 16:28 prime-supported.log -rw-r--r--  1 root   root            1.2K Aug 27 16:28 gpu-manager.log   I have no experience interpreting log files, so I don't know if anything here is out of the ordinary.  If the kernel version is relevant, the output of uname -r is 5.0.0-25-generic.  My questions are, 1. Why is my HDD light flashing, even though there is no obvious disk activity, 2. Does this indicate some kind of problem with my system that needs to be fixed, and 3. If so, how do I fix it? The light itself does not bother me -- if this is just a sign of a normal, healthy Ubuntu install, then no problem. My concern is that something is wrong, and if so, I would like to fix it.  Thanks in advance for your time.  In response to heynnema (in the original posting of this question), the issue occurs even at the log-in screen, before I log in. So, it is not tied to my user account. However, it does not occur in the BIOS, suggesting that it is specific to Kubuntu (or at least, to the SSD Kubuntu is installed on). Is there any way to make a hotkey turn the screen off? How can I make a script (or make some changes) to allow me to turn the screen off in Ubuntu (12.04) whenever I want, the way thevscreen can be turned off in Cellphones?  And how can I make a combination of keys (a shortcut) to execute that script?  I want to conserve power.  I've seen this question    but there is no hotkey for it.  Moreover, in the answer, it is said that there are many ways to accomplish this so I'd like to know more. Suppose $A$ and $B$ are similar matrices. Show that $A$ and $B$ have the same eigenvalues with the same geometric multiplicities.      Similar matrices: Suppose $A$ and $B$ are $n\times n$ matrices over $\mathbb R$ or $\mathbb C$. We say $A$ and $B$ are similar, or that $A$ is similar to $B$, if there exists a matrix $P$ such that $B = P^{-1}AP$. How can I crack a 16 bit hash/CRC/checksum with a large sample set? What can you say about $f$ and $g$ in the case that $fg$ is 1) Injective, 2) Surjective - Cohn - Classic Algebra Page 15 Why can't I destroy or place blocks? I'm playing on a Survival world with cheats on, "easy" difficulty, and at night in-game. I didn't have a sword or anything to make a sword with, and I was starving, so I switched to Creative to give myself a stack of food and a bed to set my spawn point. When I switched back to Survival, I couldn't destroy or place blocks. I'm on single player, and my Internet is fine, and I can destroy blocks still if I switch to creative. I've tried resetting the button one, and reloading the map, and it still doesn't work. I've even tried deleting everything I gave myself in Creative. This happened before on a different world and I ended up deleting it.  This only happens on this world. How do I fix it?  If I know I'm in the correct game mode, what else can cause this?  Are there different causes in multiplayer? Do rainbows have ultraviolet bands and infrared bands? We have seen that rainbows looks so colorful as we are only able to see only the visible light. But Do they also have ultraviolet bands and infra-red bands, that we are unable to see? I know someone has already asked the same question but I am concern about the specific ultraviolet and infrared bands only rather than any other wavelength. Can the 'bin size' in a histogram be thought of as a regularity constraint? How much longer will my 10 year old frame last? Assume $R=(\mathcal{U}_n)_n$ is a sequence of distinct ultrafilters on some set $X$. Since every Hausdorff space has an infinite discrete subspace, there is a subsequence $R=(\mathcal{V}_n)_n$ of $R=(\mathcal{U}_n)_n$ such that $\{\mathcal{V}_n|n \in \mathbb{N} \}$ is a discrete subspace of $\beta X$. In particular, there is a sequence $(A_n)_n$ of sets with $A_n \in \mathcal{V}_m$ if and only if $m =n$. If we let $B_n=A_n - (A_0 \cup...\cup A_{n−1})$, then the sequence $(B_n)_n$ is pairwise disjoint and $B_n \in \mathcal{V}_m$  iff $m=n$. If we let $B =\cup_n B_{2n}$, then $B \in \mathcal{V}_m$ if and only if $m$ is even. In other words, if $B =\{ \mathcal{V} \in βX|B \in \mathcal{V}\}$, then $B$ is a clopen set with $\mathcal{V}_m \in B$ iff $m$ is even. Therefore, we conclude that the sequence $(\mathcal{V}_m)_m$ cannot converge to any point, so the sequence $(\mathcal{U}_n)_n$ cannot converge to any point either.     I would like to know that:      (1) Why "$B_n \in \mathcal{V}_m$  iff $m=n$"? And " $B =\cup_n B_{2n}$, then $B \in \mathcal{V}_m$ if and only if $m$ is even "?      (2)$B$ is a clopen set with $\mathcal{V}_m \in B$ iff $m$ is even A concise definition of a frame of reference in Newtonian mechanics? I've read  on frame of reference and also followed all of the references cited in the text (Salençon, Brillouin, Norton, etc) but I'm struggling to find any concise definition in all of that.   I would like a concise definition for a frame of reference in the context of Newtonian mechanics. This definition should not involve any additional qualifiers such as inertial and must be mature enough as to differentiate a frame of reference and a coordinate system. Is there one such definition? How can I mirror weight painting? How can I mirror my weight painting to the opposed side of my character? I know that there is Mirror function, but it doesn't assign the weight to bones on the opposed side. Can I do it manually?