Batch file to delete/remove folders old of xx days
Batch file to delete files older than N days
$1+a$ and $1-a$ in a ring are invertible if $a$ is nilpotent I recently purchased a MacBook Pro 13&quot; with the M1 chip and transferred all my data over using a Time Machine backup. Homebrew packages are currently installed in /usr/local/opt/ but it is my understanding that they should be under /opt/homebrew for Apple Silicon Macs. How can I:  Get the list of packages I currently have installed Remove those from /user/local/opt Reinstall them under /opt/homebrew  I kind of assumed Homebrew would be clever enough to do this automatically but apparently it needs some manual maintenance. Here's my Homebrew config if it helps: HOMEBREW_VERSION: 2.7.2 ORIGIN: https://github.com/Homebrew/brew HEAD: dad7dc6a1498b80770d98f2d7cd6fb927c300bbb Last commit: 3 days ago Core tap ORIGIN: https://github.com/Homebrew/homebrew-core Core tap HEAD: 2b1d79d038bffdbfcee93283051d48919a4caf3d Core tap last commit: 16 hours ago Core tap branch: master HOMEBREW_PREFIX: /usr/local HOMEBREW_REPOSITORY: /usr/local/Homebrew HOMEBREW_CELLAR: /usr/local/Cellar HOMEBREW_CASK_OPTS: [] HOMEBREW_MAKE_JOBS: 8 Homebrew Ruby: 2.6.3 =&gt; /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby CPU: octa-core 64-bit arm_firestorm_icestorm Clang: 12.0 build 1200 Git: 2.30.0 =&gt; /usr/local/bin/git Curl: 7.64.1 =&gt; /usr/bin/curl macOS: 11.1-arm64 CLT: 12.3.0.0.1.1607026830 Xcode: N/A Rosetta 2: false  Thanks in advance! Existence of a Riemannian metric inducing a given distance. Let $M$ be a smooth, finite-dimensional manifold. Suppose $M$ is also a metric space, with a given distance function $d: M \times M \rightarrow \mathbb{R}_{+}$, which is compatible with the original (manifold) topology on $M$.  Question: is there a Riemannian metric $g$ on $M$ such that the distance $$d_g(p, q) = \inf_{\gamma \in \Omega(p, q)} L_g(\gamma)$$ coincides with $d$?  I believe that this setting is very standard, but for the sake of completeness: $L_g$ denotes the Riemannian length of the curve $\gamma$, and $\Omega(p, q)$ the set of all piecewise smooth curves $\gamma : [a, b] \rightarrow M$ s.t. $\gamma(a) = p$ and $\gamma(b) = q$. Thanks in advance. What I am looking for is to have system wide implementation of sound enhancements like bass boosts, echoes, Fidelity, Stereo enhancement and so on.  Audio Video players have their own equalizer but they enhance only the audio / video files they are playing.  So to enhance sounds playing such as: YouTube, Spotify, System Sound, etc. I need a enhancer software. Back in Windows, I used to use SRS HD audio lab to do the same.  P.S. I have a horrible Speaker set. Maps from subsets of $\mathbb{R}^2$ that are either open/closed/continuous I'm self studying J. Lee's Introduction to Topological Manifolds, and after doing all other exercises on chapter 2, I can't seem to come with the proper counterexamples for this one.      For each of the following properties, give an example consisting of two subsets $X, Y \subset \mathbb{R}^2 $, both considered as topological spaces with their Euclidean topologies, together with a map $f: X \rightarrow Y$ that has the indicated property.         Open but not closed/continuous   Closed but not open/continuous    Continuous but not open/closed         etc... (all cases)   I think the reason for my difficulty is a lack of geometric intuition of what open, closed and continuous maps look like as deformations of shapes in $\mathbb{R}^2$ (I can construct counterexamples from artificial made up spaces).   I tried squashing balls and 'pumping space' into lines, as well as joining strips in annulus shapes, but all the examples I seem to come up with are either too well behaved (i.e. all 3) or too misbehaved.   Instead of a case by case answered I would prefer a couple worked out cases and some intuition on how to visualise open / closed maps in this context. How can I use std::maps with user-defined types as key? (Disclaimer: I've read the  and I do understand that this is bordering on off-topic since it's about consumer devices. However I hope that I've managed to make enough on-topic by asking about why it is the way it is, and what is the explanation from an electromagnetic point of view - in other words, what laws of electricity and what practical considerations have gone into these decisions).  I recently bought a power tool and in its manual I found a few peculiar safety rules. I cannot see why they would be there, although reading up more it seems that they are commonplace. My understanding of electricity is limited (just about enough to be dangerous), so I'm hoping to expand it. :)  The rules are:   Don't use an extension cord longer than 25m. Considering this is an outdoors tool, this limitation is severely restrictive. The best explanation I've seen is that longer cables would simply have too high of a resistance and the tool wouldn't be able to operate at full power. But this argument doesn't convince me. The tool is rated at 2.4kW, and it's meant to be used with 220V AC power source, which means it uses about 11 amps of current. All the extension cords I've ever come across have at least 16A limitation, so there is quite a reserve still. In addition, the power has to travel much, much further to get to my house, and even after the meter it still takes probably close to those same 25m to get to the power outlet. Why only 25m after the outlet? The resistance of the cables isn't that big, is it? Don't daisy-chain extension cords. I suspect this is a variation of the above - don't exceed 25m; every connection adds additional contact resistance; water in the outdoors connections can be a problem - in general, it just adds risk. However, apart from the water in the contacts, the rest seems to me to be practically negligible. Is there really a significant contact resistance? Assuming that the extension cords are in a good shape. Make sure that the power cord is entirely unrolled. This is another odd one. My suspicion is that it has to do with inductive resistance. But is it really that strong? Wherever I've seen people actually wanting to create an electromagnet, it's pretty much hard work. You need a lot of neat, tightly-wound loops of wire. An extension cord has a lot of insulator around it, spacing the wires pretty far apart, and the loops are very chaotic. In addition, if that was a problem, why do  exist? They're used especially when you need a very long extension cord, and you don't need to unroll them completely every time you want to use them. Solved: OK, I was off the mark. The correct answer (also a ) has to do with the wire heating up from being used close to its limits. When coiled together, the temperature can go pretty high and melt the cables. Not fun. If $f$ is measurable and $fg$ is in $L^1$ for all $g \in L^q$, must $f \in L^p$? Label rows of a matrix by characters How to add label to index the rows and columns of the matrix ? because I want to number the line outside the matrix       \[     \begin{array}{lc}       \ Mat_{\varPhi to M} &amp; \left(\begin{array}{@{}ccccc@{}}             1 &amp; 1 &amp; 1 &amp; 1 &amp; 1 \\             0 &amp; 1 &amp; 0 &amp; 0 &amp; 1 \\             0 &amp; 0 &amp; 1 &amp; 0 &amp; 1 \\             0 &amp; 0 &amp; 0 &amp; 1 &amp; 1 \\             0 &amp; 0 &amp; 0 &amp; 0 &amp; 1               \end{array}\right) \\[15pt]     \end{array}     \] Are the limits $\lim\limits_{n\to \infty }\left|\frac{a_{n+1}}{a_n}\right|\,$ and $\lim\limits_{n\to \infty }\sqrt[n]{|a_n|}\,$ equal? Let consider the power series $$ \sum_{k=1}^\infty a_kx^k. $$ We know that it converges when  $$\lim_{n\to \infty }\sqrt[n]{|a_n|}|x|&lt; 1\quad\text{or}\quad |x|&lt; \frac{1}{\lim_{n\to \infty }\sqrt[n]{|a_n|}}$$  But D'Alembert test tells us that it converges if $$|x|&lt; \frac{1}{\lim_{n\to \infty }\left|\frac{a_{n+1}}{a_n}\right|},$$ so since the radius of convergence is unique, we should have that $$\lim_{n\to \infty }\sqrt[n]{|a_n|}=\lim_{n\to \infty }\left|\frac{a_{n+1}}{a_n}\right|.$$  I tried to prove it, but this result looks strange to me. So if it doesn't work always, how can we have those to limit as radius of convergence? I guess the equality of those two limit should be true most of the time.  So under what conditions is it true? Benevolent aliens who (initially) refuse to show themselves This is a sci-fi book where aliens arrive on Earth and push Earth towards world peace, but refuse to reveal themselves physically. When the aliens finally do show themselves, we find that they       look like .   I recall that the aliens seemed benevolent, but that humanity did not like the direction they were being told to go. I cannot remember the ending or if the aliens turned out to be truly benevolent. Let $G$ be  a group and $H$ be a subgroup of $G$ of index $2$ .Then show that if $a,b\notin H$ then $ab\in H$.   $a,b\notin H\implies aH,bH\neq H\implies $ $aH=bH$  since $H$ has only two distinct left cosets in $G$.  $\implies a^{-1}b\in H$  How to show that $ab\in H$ from here? strcmp on a line read with fgets Another part of my daily  on SE sites.  When viewing a question and it's time to move on, I'll often simply click one of the tags in the question to bring me back to a list of questions with that tag.  This doesn't work in the Android app.  Obligitory screenshot.  I tried to draw a finger that looked like it was tapping a tag, but it ended up looking like, well...  something else, let's say. I'm reading a lot of documentation on sed, and am still stumped on my particular use case.  I want to replace this line in a conf file with my own line:  Replace this line: #maxmemory &lt;bytes&gt; with: maxmemory 26gb  This is what I tried:  sed s/maxmemory.*bytes.*/maxmemory 26gb/ /etc/redis/redis.conf  I get the error: sed: -e expression #1, char 30: unterminated `s' command  Which stumps me because I don't know what that means. So my question is:  How can I accomplish what I want? What does that error mean? (so I can learn from it) How can I obtain the limit of the series     $$\sum_{n=1}^{\infty} \frac{2^{[\sqrt{n}]}+2^{-[\sqrt{n}]}}{2^n}$$   Where $[\ \ ]$ is . Let $ f: \mathbb {R} \rightarrow {\mathbb {R}} $ be given by   $$ f (x) = \left \{\begin {matrix} \sin ({\frac {1} {x}}), &amp; \text {if} \phantom {a} x \neq 0; \\  c, &amp; \text {if} \phantom {a} x = 0 \end {matrix} \right. $$ where $ c \in [-1,1]$. For what values ​​of $c$ is there an antiderivative of $f$?  I do not know of a theorem of the form "if and only if" that  it tells me when a function $ f $ has no antiderivative.  Anyone have a suggestion? How can you depend on test code from another module in Maven?    Example, I have 2 modules:   Base Main   I would like a test case in Main to extend a base test class in Base.  Is this possible?  Update: Found an , which involves creating a test jar. Why and how can you hear explosions in space in Star Wars? Considering that sound can't travel through vacuum. "shyer" or "shier" My Longman dictionary states that the comparative of 'shy' is 'shyer'. However, at least two online dictionaries also give the form 'shier' as being acceptable:  and . On an English language  I came across a reference to British (shyer) vs. American (shier) spelling. But an Ngram chart shows that even in American English 'shyer' is much more used.  My problem is that I've been told that it is definitely wrong, but if it's in dictionaries then... has there been a change to what is wrong?   P.S.: