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Problem: Derive the double angle identities $$\sin(2\theta) = 2\sin(\theta)\cos(\theta)\\\ \cos(2\theta) = \cos^2(\theta) – \sin^2(\theta)$$ Solution: Recall from linear algebra how one rotates a point in the plane. The matrix of rotation (derived by seeing where $ (1,0)$ and $ (0,1)$ go under a rotation by $ \theta$, and writing those coordinates in the columns) is $$A = \begin{pmatrix} \cos(\theta) & -\sin(\theta) \\\ \sin(\theta) & \cos(..
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Problem: Derive the double angle identities $$\sin(2\theta) = 2\sin(\theta)\cos(\theta)\\\ \cos(2\theta) = \cos^2(\theta) – \sin^2(\theta)$$ Solution: Recall from linear algebra how one rotates a point in the plane. The matrix of rotation (derived by seeing where $ (1,0)$ and $ (0,1)$ go under a rotation by $ \theta$, and writing those coordinates in the columns) is $$A = \begin{pmatrix} \cos(\theta) & -\sin(\theta) \\\ \sin(\theta) & \cos(..
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Donations If you appreciate this tool, please consider a donation. It truly helps me out. PayPal : GitHub : Ko-Fi : Playing Minecraft, I like making circular things. I used a chart while I was building, but wanted to be able to make variable size ovals which is something I couldn't find a decent chart of or generator capable of, so I created this! Go Fullscreen Show Old Generator Fo..
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Donations If you appreciate this tool, please consider a donation. It truly helps me out. PayPal : GitHub : Ko-Fi : Playing Minecraft, I like making circular things. I used a chart while I was building, but wanted to be able to make variable size ovals which is something I couldn't find a decent chart of or generator capable of, so I created this! Go Fullscreen Show Old Generator Fo..
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This is not going to be a very popular opinion considering my reader demographic, but I’ve grown a little sick of the gaming community as a whole and recent whining about Diablo 3 has triggered…well…this post. Why do so many of us have to be so negative about everything that comes out? Ok, I understand things like being frustrated about server downtime, or installation problems, or major bugs. I completely understand the frustration there..
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Why I recommend CloudFlare and why you should try it too
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www.jimwestergren.com
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14 years ago
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eng
CloudFlare is a both a proxy and a CDN (content delivery network). It was recommended to me by Magnus Bråth. Quoted from them: On average, a website on CloudFlare loads twice as fast uses 60% less bandwidth has 65% fewer requests is way more secure All for free! Never heard of them? According this recent [...]
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Why I recommend CloudFlare and why you should try it too
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www.jimwestergren.com
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14 years ago
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eng
CloudFlare is a both a proxy and a CDN (content delivery network). It was recommended to me by Magnus Bråth. Quoted from them: On average, a website on CloudFlare loads twice as fast uses 60% less bandwidth has 65% fewer requests is way more secure All for free! Never heard of them? According this recent [...]
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Why I recommend CloudFlare and why you should try it too
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www.jimwestergren.com
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14 years ago
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eng
CloudFlare is a both a proxy and a CDN (content delivery network). It was recommended to me by Magnus Bråth. Quoted from them: On average, a website on CloudFlare loads twice as fast uses 60% less bandwidth has 65% fewer requests is way more secure All for free! Never heard of them? According this recent [...]
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Why I recommend CloudFlare and why you should try it too
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www.jimwestergren.com
-
14 years ago
-
eng
CloudFlare is a both a proxy and a CDN (content delivery network). It was recommended to me by Magnus Bråth. Quoted from them: On average, a website on CloudFlare loads twice as fast uses 60% less bandwidth has 65% fewer requests is way more secure All for free! Never heard of them? According this recent [...]
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Not many coding updates lately because of other work. I’m working on the game a little each day and will post when there’s a substantial update to make. Box2D is still driving me a little insane on a regular basis, but I’m getting the hang of it. Meanwhile, a quick overview of the past few days:
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I recently read this post entitled “(Some) ORM Haters Do Get It” and I wanted to make a few points in favour of ORM’s. The author of the post argues that ORM’s are bad because of impedance mismatch. I don’t know enough about that subject to comment on it but I have been using ORM’s long enough to th...
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I recently read this post entitled “(Some) ORM Haters Do Get It” and I wanted to make a few points in favour of ORM’s. The author of the post argues that ORM’s are bad because of impedance mismatch. I don’t know enough about that subject to comment on it but I have been using ORM’s long enough to th...
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Apparently not many. I have been monitoring how the search has been used since I rolled out code search and noticed that most people are just typing in search terms and not regex search terms. Of course this means some results are not what people are expecting. I have thus changed the way searches work. It now does an exact match of whatever it is you are looking for UNLESS you wrap your search term in / in which case it will default to a..
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It was my fault that Adam became a zombie. I see it in slow motion when I close my eyes: his hand reaching out to slam against my chest and push me into the wall as he throws himself between me and the oncoming Infected. I still see the sticky spiderweb of drool and blood stretching between its teeth as it comes at us with gaping mouth and hollow eyes and I still hear the crunch of tooth on flesh as it latches onto Adam’s bare shoulder.
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Recently, I have noticed that there are quite a few wrappers around git to give you a nicer interface to work with. The new commands promise to be easy to remember and make your life less frustrating. I find these a little silly because git on its own is a great tool. Here I’m going to describe how I use git to convince you (and myself) that it’s not that hard. Cloning This couldn’t be any simpler: git clone git://github.com/honza/dot....
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Recently, I have noticed that there are quite a few wrappers around git to give you a nicer interface to work with. The new commands promise to be easy to remember and make your life less frustrating. I find these a little silly because git on its own is a great tool. Here I’m going to describe how I use git to convince you (and myself) that it’s not that hard. Cloning This couldn’t be any simpler: git clone git://github.com/honza/dot....
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Affecting the world and other things smelling up our fridge - by Joseph Hewitt
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liza.io
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14 years ago
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eng
Liza: This post, aside from this brief introduction, was written by Joseph Hewitt . I met Joseph at Interzone Games, where he tried to do his job as Creative Director while I waved bug lists at him and got on his case about design specs. He is now Creative Director at Jet Set Games, where he works on Highborn and makes all kinds of awesome stuff happen. Joseph also has his own blog: Working as Designed . Oh and he worked on one of the ..
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Good points, Raymond. One reason people find it hard to "read the source" is, as you correctly noted, largish repositories and checkouts with many sub-directories. Conventional tools (find | xargs grep) are somewhat lacking in this respect, so some folks use special source-searching tools like ack. I wrote 'pss' (https://bitbucket.org/eliben/pss - shameless plug!) to be a Python clone of ack, precisely for the goal of making search inside ..
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For Python code, IPython is a big help with this. You can look up the source code for any module, function or object - so long as it's defined in Python - with "foo??".
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I usually consider it a weakness in the docs if someone needs to view code I've given them in a library in order to make effective use of it. But these days we take that a little too far and actively hide the code and pretend it doesnt exist. I think linking to the source from the docs is a great idea.
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Oradebug hanganalyze with a prelim connection and “ERROR: Can not perform hang analysis dump without a process state object and a session state object.”
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tanelpoder.com
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14 years ago
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eng
Back in the (really) old days, systemstate dumps had to be used for diagnosing hangs and finding blockers of hung databases. Basically you just identified which resource your waiting sessions were waiting for and then scanned through the rest of the system state dump to see which session held that particular resource (note that over time the instrumentation and systemstate dumps have evolved to resolve and dump the blocker information right..
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Oradebug hanganalyze with a prelim connection and “ERROR: Can not perform hang analysis dump without a process state object and a session state object.”
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tanelpoder.com
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14 years ago
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eng
Back in the (really) old days, systemstate dumps had to be used for diagnosing hangs and finding blockers of hung databases. Basically you just identified which resource your waiting sessions were waiting for and then scanned through the rest of the system state dump to see which session held that particular resource (note that over time the instrumentation and systemstate dumps have evolved to resolve and dump the blocker information right..
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View the site here: https://movies.tomforb.es or the code here To distract me from my ever approaching 1st year exams I decided to create a site that recommends people films to watch based upon their previous viewing habits. I gave it to my girlfriend to use and evaluate and she gave positive feedba...
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View the site here: https://movies.tomforb.es or the code here To distract me from my ever approaching 1st year exams I decided to create a site that recommends people films to watch based upon their previous viewing habits. I gave it to my girlfriend to use and evaluate and she gave positive feedba...
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I encountered some code recently where a GUI client was listening for Object updates from a multi-threaded server, and it was using the version number on the Object to determine whether the incoming Object was the latest version. The server incremented the version of the Object by inserting a new row into a table in the database and using the primary key as the version number. Now consider the case multi-threaded case where two threads, T..
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This post is a list of many of the reasons to use Postgres, much this content as well as how to use these features will later be curated within PostgresGuide.com . If you need to get started check out Postgres.app for Mac, or get a Cloud instance at Heroku Postgres for free Last week I did a post on the many reasons to use Postgres . My goal with the post was two fold: Call out some of the historical arguments against it that don....
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This post is a list of many of the reasons to use Postgres, much this content as well as how to use these features will later be curated within PostgresGuide.com . If you need to get started check out Postgres.app for Mac, or get a Cloud instance at Heroku Postgres for free Last week I did a post on the many reasons to use Postgres . My goal with the post was two fold: Call out some of the historical arguments against it that don....
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A belated post about the first Guild Wars 2 Beta Weekend Event / @GuildWars2
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liza.io
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14 years ago
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eng
Over the past few days I’ve been processing my thoughts about the Guild Wars 2 Beta Weekend Event, which was now a couple of weeks ago.
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False Proof – 2 = 4, As the Limit of an Infinite Power Tower
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www.jeremykun.com
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14 years ago
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eng
Problem: Prove that $ 2 = 4$. Solution: Consider the value of the following infinitely iterated exponent: $$\displaystyle \sqrt{2}^{\sqrt{2}^{\sqrt{2}^{\cdot^{\cdot^{\cdot}}}}}$$ Let $ a_n = \sqrt{2} \uparrow \uparrow n$, that is, the above power tower where we stop at the $ n$-th term. Then $ a_n$ is clearly an increasing sequence, and moreover $ a_n \leq 4$ by a trivial induction argument: $ \sqrt{2} \leq 4$ and if $ a_n \leq 4$ then $ a_..
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False Proof – 2 = 4, As the Limit of an Infinite Power Tower
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www.jeremykun.com
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14 years ago
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eng
Problem: Prove that $ 2 = 4$. Solution: Consider the value of the following infinitely iterated exponent: $$\displaystyle \sqrt{2}^{\sqrt{2}^{\sqrt{2}^{\cdot^{\cdot^{\cdot}}}}}$$ Let $ a_n = \sqrt{2} \uparrow \uparrow n$, that is, the above power tower where we stop at the $ n$-th term. Then $ a_n$ is clearly an increasing sequence, and moreover $ a_n \leq 4$ by a trivial induction argument: $ \sqrt{2} \leq 4$ and if $ a_n \leq 4$ then $ a_..
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False Proof – 2 = 4, As the Limit of an Infinite Power Tower
-
www.jeremykun.com
-
14 years ago
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eng
Problem: Prove that $ 2 = 4$. Solution: Consider the value of the following infinitely iterated exponent: $$\displaystyle \sqrt{2}^{\sqrt{2}^{\sqrt{2}^{\cdot^{\cdot^{\cdot}}}}}$$ Let $ a_n = \sqrt{2} \uparrow \uparrow n$, that is, the above power tower where we stop at the $ n$-th term. Then $ a_n$ is clearly an increasing sequence, and moreover $ a_n \leq 4$ by a trivial induction argument: $ \sqrt{2} \leq 4$ and if $ a_n \leq 4$ then $ a_..
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First a huge thanks to all organizers of conferences, but especially for those that organize not-for-profit conferences. I do understand its a great amount of work, and in nearly all cases have greatly appreciated the experience made available by the work they put into it. As for some guidance. I’ve been on nearly all sides of the conference with the exception of organizing, so again organizers please don’t take offense to the feedback. ....
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