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Search found 585 results on 24 pages for 'numerical equations'.

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• How to distill / rasterize a PDF in Linux

  - by Sampo

  We have a printer at our office that prints PDF files from a USB stick. It prints most files okay, but it has problems with some, especially ones generated with Latex. Some PDFs it simply refuses to print, some PDFs it prints with courier-type font, and some it prints fine except for equations. I'm looking for a way to "distill" PDFs into a dead-sure format to print. Either by simplifying / normalizing the PDF to the point that any renderer will render it correctly, or by simply making each page a 600dpi raster image in the PDF. (I could split the PDF into individual raster images and combine them manually, but I want something scriptable.) The output file size doesn't matter, as long as it's sure to print, has A4 paper size (or the original) and 300~600dpi resolution.

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• Change filtering method used by Firefox when zooming

  - by peak

  I often zoom in a step or two when reading long texts in Firefox, but when I do so the images become super blurry. It's not really a big deal but when reading text on images (mathematical equations mostly), it's a bit distracting. It seems as if they are scaled using only bilinear interpolation. If I scale an image the same amount in for example Paint.NET or Photoshop the result is much better. Is there any way to change the filtering method used by Firefox to bicubic or another better method? I am Using Firefox 3.5 on Windows BTW.

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• How to implement curved movement while tracking the appropriate angle?

  - by Vexille

  I'm currently coding a 2D top-down car game which will be turn-based. And since it's turn-based, the cars won't be controlled directly (i.e. with a simple velocity vector that adjusts its angle when the player wants to turn), but instead it's movement path has to be planned beforehand, and then the car needs to follow the path when the turn ends (think Steambirds). This question has some interesting information, but its focus is on homing-missile behaviour, which I kinda had figured out, but doesn't really apply to my case, I think, since I need to show a preview of the path when the player is planning his turn, then have the car follow that path. In that same question, there's an excellent answer by Andrew Russel which mentions Equations of Motion and Bézier's Curve. Some of his other suggestions of implementation are specific to XNA though, so they don't help much (I'm using Marmalade SDK). If I assume Bézier's Curve as the solution of choice, I'm left with one specific problem: I'll have the car's position (the first endpoint) and the target/final position (the last endpoint), but what should I use as the control point (assuming a square/quadratic curve)? And whether I use Bézier's Curve or another parametric equation, I'd still be left with another issue: the car can't just follow the curve, it must turn (i.e. adjust its angle) accordingly. So how can I figure out which way the car should be pointing to at any given point in the curve?

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• Top Down RPG Movement w/ Correction?

  - by Corey Ogburn

  I would hope that we have all played Zelda: A Link to the Past, please correct me if I'm wrong, but I want to emulate that kind of 2D, top-down character movement with a touch of correction. It has been done in other games, but I feel this reference would be the easiest to relate to. More specifically the kind of movement and correction I'm talking about is: Floating movement not restricted to tile based movement like Pokemon and other games where one tap of the movement pad moves you one square in that cardinal direction. This floating movement should be able to achieve diagonal motion. If you're walking West and you come to a wall that is diagonal in a North East/South West fashion, you are corrected into a South West movement even if you continue holding left (West) on the controller. This should work for both diagonals correcting in both directions. If you're a few pixels off from walking squarely into a door or hallway, you are corrected into walking through the hall or down the hallway, i.e. bumping into the corner causes you to be pushed into the hall/door. I've hunted for efficient ways to achieve this and have had no luck. To be clear I'm talking about the human character's movement, not an NPC's movement. Are their resources available on this kind of movement? Equations or algorithms explained on a wiki or something? I'm using the XNA Framework, is there anything in it to help with this?

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• How can I unit test rendering output?

  - by stephelton

  I've been embracing Test-Driven Development (TDD) recently and it's had wonderful impacts on my development output and the resiliency of my codebase. I would like to extend this approach to some of the rendering work that I do in OpenGL, but I've been unable to find any good approaches to this. I'll start with a concrete example so we know what kinds of things I want to test; lets say I want to create a unit cube that rotates about some axis, and that I want to ensure that, for some number of frames, each frame is rendered correctly. How can I create an automated test case for this? Preferably, I'd even be able to write a test case before writing any code to render the cube (per usual TDD practices.) Among many other things, I'd want to make sure that the cube's size, location, and orientation are correct in each rendered frame. I may even want to make sure that the lighting equations in my shaders are correct in each frame. The only remotely useful approach to this that I've come across involves comparing rendered output to a reference output, which generally precludes TDD practice, and is very cumbersome. I could go on about other desired requirements, but I'm afraid the ones I've listed already are out of reach.

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• Calculating a child Position, Rotation and Scale values?

  - by Sergio Plascencia

  I am making my own game editor(just for fun) anyway I have problem that I had several days trying to resolve but I have been unsuccessful. Here goes... I have an object "A": Position: (3,3,3), Rotation: (45,10,0), Scale(1,2,2.5) And an object "B": Position: (1,1,1), Rotation: (10,34,18), Scale(1.5,2,1) I now make a parent/child relationship. "B" is a child of "A": A |--B When I do the relationship I need to re-calculate the Child("B") Position, Rotation and Scale such that it maintains its current position, rotation and scale(Location in world). So for child position "B" it would now be (-2, -2, -2) since now "A" it is center and (-2, -2, -2) will keep the object in its same position. I think I got the Position and scale figure out, but rotation I cant. So I was trying to figure out what to do and what I did is opened Unity and run the same example and I did noticed that when making an abject a child object the child object did not moved at all but had its Position, Rotation and Scale values changed(Related to the parent). For example: Unity (Parent Object "A"): Position: (0,0,0) Rotation: (45,10,0) Scale: (1,1,1) Unity (Child Object "B"): Position: (0,0,0) Rotation: (0,0,0) Scale: (1,1,1) When making it a parent child relation("B" is a child of "A") the child object("B") in its Rotation values now has: X: -44.13605 Y: -14.00195 Z: 9.851074 If I plug the same values to my editor(To the child "B" rotation X, Y, Z values) the object does not move at all. So I basically need to know how did Unity arrive at those rotation values for the child(What are the calculations?). If you can help and put all the equations for the Position, Rotation or Scale then I can double check I am doing it correctly but with the Rotation I really need help. Thanks!

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• Recommendations for a web-based help system

  - by ggkmath

  Hi Experts, I'm putting together a fairly large GUI. I'm a tech person, but more on the hardware side, not software. I'm wondering what software package would be best suited to enable me to generate a web-based help-system. Preferably it takes care of a lot of coding, allowing me to focus on the content. For example, the user would click on a link in the GUI when they have a question, that brings them to a web-based Help Guide, for example, providing an overview of how to use the GUI, perhaps a searchable index (key-word based index), table of contents, etc, for navigating through the Help Guide. My first thought was to program everything in XHTML using Dreamweaver, but my layout requirements are fairly modest (just figures and text, maybe a few equations), and I'd prefer not to spend a lot of time concentrating on the programming. Was wondering if any software existed that made generating web-based navigatable pages easy to create/publish. Again, I'm not really a programmer, so if there's something obvious out there, I'm probably not aware of it. Any advice much appreciated! Thanks in advance.

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• Which Bliki (Blog+Wiki) solution can you recommend?

  - by asmaier

  I'm searching for a good Bliki solution, meaning a combination of blog and wiki that I can install on my own web space. I would like to be able to write articles in the wiki style much like with media wiki. So I want to use a wiki markup language, have a revision history, comments, internal links to other pages (maybe in other languages) and be able to collaboratively edit the articles. On the other side I would like to have a blog-like view on my articles, showing new articles (and changes to existing articles) in a time ordered fashion. It would be nice if it would be possible to search through the articles and also tag the articles, so one could generate a tag cloud for the articles. A nice feature would also be to be able to order the articles according to views or even a voting system for the articles. Good would also be a permission system to keep certain articles private, showing them only to people logged in to the platform. Apart from these nice to have features an absolute must have feature for the Bliki platform I'm searching is the possibility to handle math equations (written in LaTeX syntax) and display them either as pictures like media wiki or even better using Mathjax. At the moment I'm using a web service called wikiDot which offers some of the mentioned features, however the free version shows to much advertisements, the blog feature is not mature, the design is quite ugly and loading of the page is often slow. So I want to install a Bliki solution on my own webspace. Can you recommend any solution for that?

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• Documenting mathematical logic in code

  - by Kiril Raychev

  Sometimes, although not often, I have to include math logic in my code. The concepts used are mostly very simple, but the resulting code is not - a lot of variables with unclear purpose, and some operations with not so obvious intent. I don't mean that the code is unreadable or unmaintainable, just that it's waaaay harder to understand than the actual math problem. I try to comment the parts which are hardest to understand, but there is the same problem as in just coding them - text does not have the expressive power of math. I am looking for a more efficient and easy to understand way of explaining the logic behind some of the complex code, preferably in the code itself. I have considered TeX - writing the documentation and generating it separately from the code. But then I'd have to learn TeX, and the documentation will not be in the code itself. Another thing I thought of is taking a picture of the mathematical notations, equations and diagrams written on paper/whiteboard, and including it in javadoc. Is there a simpler and clearer way? P.S. Giving descriptive names(timeOfFirstEvent instead of t1) to the variables actually makes the code more verbose and even harder too read.

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• What is the best approach for database design with lots of columns?

  - by Pratyush

  I am writing a query based financial application. It lets the user to write complicated equations (much like WHERE part of an SQL query) and find companies matching those criteria. For the above, I currently have more than 500 columns in the database table (each column representing a financial field). Example of Columns are: company_name, sales_annual_00, sales_annual_01, sales_annual_02, sales_annual_03, sales_annual_04, protit_annual_00, profit_annual1...(over 500 such columns). The number of rows is around 5000. Going forward, I would like to further increase the number of columns/financial-fields. For the above I would like to get help regarding: 1) What is the best database design approach? Is it ok to have these many number of columns? 2) How can it be normalized? (User can use any of these fields in search criteria). 3) Is it ok to stick with MySQL, or modern document based databases like MongoDB should be better for it? P.S. (Update): I have been using MySQL till now and a running example of the usage is at: http://screener.in/companies/89/Formula-- In above there around 500 fields/columns to create your query on, however, I seek to increase that number to much more in future.

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• Calculating a child object's Position, Rotation and Scale values?

  - by Sergio Plascencia

  I am making my own game editor, but have encountered the following problem: I have two objects, A and B. A's initial values: Position: (3,3,3), Rotation: (45,10,0), Scale(1,2,2.5) B's initial values: Position: (1,1,1), Rotation: (10,34,18), Scale(1.5,2,1) If I now make B a child of A, I need to re-calculate the B's Position, Rotation and Scale relative to A such that it maintains its current position, rotation and scale in world coordinates. So B's position would now be (-2, -2, -2) since now A is its center and (-2, -2, -2) will keep B in the same position. I think I got the Position and scale figured out, but not rotation. So I opened Unity and ran the same example and I noticed that when making a child object, the child object did not move at all. but had its Position, Rotation and Scale values changed relative to the parent. For example: Unity (Parent Object "A"): Position: (0,0,0) Rotation: (45,10,0) Scale: (1,1,1) Unity (Child Object "B"): Position: (0,0,0) Rotation: (0,0,0) Scale: (1,1,1) When B becomes a child of A, it's rotation values become: X: -44.13605 Y: -14.00195 Z: 9.851074 If I plug the same rotation values into the B object in my editor, the object does not move at all. How did Unity arrive at those rotation values for the child? What are the calculations? If you can put all the equations for the Position, Rotation or Scale then I can double check I am doing it correctly but the Rotation is what I really need.

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• HTML5 Canvas Converting between cartesian and isometric coordinates

  - by Amir

  I'm having issues wrapping my head around the Cartesian to Isometric coordinate conversion in HTML5 canvas. As I understand it, the process is two fold: (1) Scale down the y-axis by 0.5, i.e. ctx.scale(1,0.5); or ctx.setTransform(1,0,0,0.5,0,0); This supposedly produces the following matrix: [x; y] x [1, 0; 0, 0.5] (2) Rotate the context by 45 degrees, i.e. ctx.rotate(Math.PI/4); This should produce the following matrix: [x; y] x [cos(45), -sin(45); sin(45), cos(45)] This (somehow) results in the final matrix of ctx.setTransform(2,-1,1,0.5,0,0); which I cannot seem to understand... How is this matrix derived? I cannot seem to produce this matrix by multiplying the scaling and rotation matrices produced earlier... Also, if I write out the equation for the final transformation matrix, I get: newX = 2x + y newY = -x + y/2 But this doesn't seem to be correct. For example, the following code draws an isometric tile at cartesian coordinates (500, 100). ctx.setTransform(2,-1,1,0.5,0,0); ctx.fillRect(500, 100, width*2, height); When I check the result on the screen, the actual coordinates are (285, 215) which do not satisfy the equations I produced earlier... So what is going on here? I would be very grateful if you could: (1) Help me understand how the final isometric transformation matrix is derived; (2) Help me produce the correct equation for finding the on-screen coordinates of an isometric projection. Many thanks and kind regards

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• Are there design patterns or generalised approaches for particle simulations?

  - by romeovs

  I'm working on a project (for college) in C++. The goal is to write a program that can more or less simulate a beam of particles flying trough the LHC synchrotron. Not wanting to rush into things, me and my team are thinking about how to implement this and I was wondering if there are general design patterns that are used to solve this kind of problem. The general approach we came up with so far is the following: there is a World that holds all objects you can add objects to this world such as Particle, Dipole and Quadrupole time is cut up into discrete steps, and at each point in time, for each Particle the magnetic and electric forces that each object in the World generates are calculated and summed up (luckily electro-magnetism is linear). each Particle moves accordingly (using a simple estimation approach to solve the differential movement equations) save the Particle positions repeat This seems a good approach but, for instance, it is hard to take into account symmetries that might be present (such as the magnetic field of each Quadrupole) and is this thus suboptimal. To take into account such symmetries as that of the Quadrupole field, it would be much easier to (also) make space discrete and somehow store form of the Quadrupole field somewhere. (Since 2532 or so Quadrupoles are stored this should lead to a massive gain of performance, not having to recalculate each Quadrupole field) So, are there any design patterns? Is the World-approach feasible or is it old-fashioned, bad programming? What about symmetry, how is that generally taken into acount?

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• I am not the most logically-organized person. Do I have any chance at being a good 'low-level' programmer?

  - by user217902

  Background: I am entering college next year. I really enjoy making stuff and solving logical problems, so I'm thinking of majoring in compsci and working in software development. I hope to have the kind of job where I can work with implementing / improving algorithms and data structures on a regular basis.. as opposed to, say, a job that's purely concerned with mashing different libraries together, or 'finding the right APIs for the job'. (Hence the word 'low-level' in the title. No, I don't wish to write assembly all day.) Thing is, I've never been the most logically-sharp person. Thus far I have only worked on hobby projects, but I find that I make the silliest of errors ever so often, and it can take me ages to find it. Like anywhere between three hours to a day to locate a simple segfault, off-by-one error, or other logical mistake. (Of course, I do other things in the meantime, like browsing SO, reddit, and the like..) It's not like I'm 'new' to programming either; I first tried C++ maybe five years ago. My question is: is this normal? Should a programmer with any talent solve it in less time? Having read Spolsky's Smart and gets things done, where he talks about the large variance in programming speed, am I near the bottom of the curve, and therefore destined to work in companies that cannot afford to hire quality programmers? I'd like to think that conceptually I'm okay -- I can grasp algorithms and concepts pretty well, I do fine in math and science, although I probably drop signs in my equations more often than the next guy. Still, grokking concepts makes me happy, and is the reason why I want to work with algorithms. I'm hoping to hear from those of you with real-world programming experience. TL;DR: I make many careless mistakes, should I not consider programming as a career?

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• Create Your Own Quick Calculator Function for the Terminal

  - by The Geek

  If you’re anything like me, you’ve always got a Terminal window open, and you probably have even assigned a hotkey to bring it up anytime. So why open up the boring calculator when you can solve equations right there on the command line? This is a simple method for creating a calculator using the built-in function support in the Bash shell. Essentially all we’re doing is assigning the question mark to run the bc command with whatever arguments you type after it. Latest Features How-To Geek ETC RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin The How-To Geek Video Guide to Using Windows 7 Speech Recognition How To Create Your Own Custom ASCII Art from Any Image Vintage Posters Showcase the History of Tech Advertising Google Cloud Print Extension Lets You Print Doc/PDF/Txt Files from Web Sites Hack a $10 Flashlight into an Ultra-bright Premium One Firefox Personas Arrive on Firefox Mobile Focus Booster Is a Sleek and Free Productivity Timer What is the Internet? From the Today Show January 1994 [Historical Video]

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• Independent HTML5 Physics Game: Any Feedback? [closed]

  - by mndoftea

  I've been independently developing a physics-based HTML5 game. I haven't used any libraries or engines; all the code, including the physics, is my own. It is free for a while on the Chrome Web Store and I was hoping that I could get some feedback on it. You can get it for Chrome here: https://chrome.google.com/webstore/detail/dbnmkpcomailjochphnmfklofkmgenci. I know this is not a normal question, but I'm happy for answers to be abstracted/generalized for broader use. Im asking here because I don't know anyone else personally who does this stuff. Any thoughts, comments or ideas you might have would be greatly appreciated! The physics system is written in JavaScript and works by setting up the differential equations of motion (plus a few conditions) and evaluating them numerically using the Euler method. The graphics are done through the HTML5 canvas and the music is done through the audio element. (Said music is in the public domain by the way). You can see the code by going to VIewView Source in Chrome.

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• Create Math Game with PHP, Ajax, Jquery

  - by Sambucasun

  I am developing a website where user can create their own game which can be joined by other users as well. It's a simple maths game which will shoot equations based on time or count specified. I want that moment user create a game, it will be listed in "current Games" section. Other users can check out the list and select the game to join. After game is created, creater should have a screen which should be having his name with display pic. Now gradually as others start joining the game, list should updated automatically. Once enough users are there i will start the game. The same list should be displayed to other users who join the game. Once game is over all will be displayed a summary list. I have gone through couple of threads but could not get clear idea. Do I need to use comet or other technology to create such game or simple PHP, Ajax or Jquery will suffice ? Also I want my website should be mobile compatible so i am designing it in html5. If i create this game using just Ajax then will there be any performance issue while playing through mobile. I am not much experienced so just need guidance for what should be appropriate or use for my requirement.

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• How do I calculate the amount of tuning needed for my server ?

  - by Low Kian Seong

  I have a server which is running a few discrete Python, Java application which most of the time imports data into a PostGreSQL database. I would like to know from people out there who have experience tuning enterprise grade servers how do i go about calculating in a holistic way the amount of tuning needed for my server for example vm.swappiness, vm.overcommit_ratio and other numerical tunings needed for my server. I tried to enable sar on my server to capture daily numbers but these are more along the lines of total numbers and I can't figure out how to allocate memory for my applications. Help would be appreciated. Thanks.

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• Is there a way to communicate DBMS with raw memory block or binaries

  - by darkcminor

  I am trying to communicate a numerical matrix operations library like LAPACK with any DBMS. Is it possible to send/receive complete matrices as binary or as a direct memory pointers to process them (it will be something like: The Outside library processes data stored in DBMS, then it computes some huge matrix stuff and then via memory block or a binary DBMS get the result from library)? The main purpose is speed and avoid passing through a flat file, and last but not least, use library toefficiently do some operations DBMS are not designed to. * Is it possible that Oracle, SQL Server, MySQL support this technique?.

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• File corruption when copying different file on raid 1

  - by Stephan

  I have a RAID 1 configuration of 2 1TB drives on a Fedora 12 box. Most of what is stored there are video files that are numerical labeled. The problem I'm having is that I had one of the video files get corrupted. I copied a replacement from a backup and replaced the bad file and now it works fine. However, after doing this the next numbered file goes from 350MB to 200KB and all but about .5 second of video disappears. If I then replace that file it happens to the next one down the line. Ex: Replace corrupt file 1.avi and file 2.avi shrinks to 200KB. Replace now corrupted 2.avi and it works but 3.avi gets screwed up. I have run SMART tests on the drives and they report fine. Does anyone have any tests I can run to try to figure out what is going on? EDIT: It is a two disk software RAID 1 with an ext4 filesystem

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• Asus EEE PC 1005HA (XP Home) refuses to connect to Virgin Mobile MiFi

  - by Dennis Wurster

  My client has an Asus EEE PC model 1005HA, and we're attempting to connect it to the WiFi network created by a VirginMobile MiFi unit. They also have a MacBook Pro with Snow Leopard that has absolutely no issue connecting to the MiFi. The specific symptom is that the netbook fails to lease an IP address from the MiFi unit. I supply the 12-digit numerical password (WPA) to the netbook, it throws a 'waiting for network' dialog with an indeterminate progress indicator, and then times out. Update: We've determined that this behavior has stopped when the EEE PC and the MiFi unit were taken out of the client's home, and to a different home that didn't have an existing wifi network. Similarly, when taken to a third location that didn't have wifi, the EEE PC and MiFi got along swimmingly. My current theory is that the existing wifi networks and the wifi leg of the MiFi unit are on the same channel and competing with one another. Perhaps the MacBook Pro has the capability to overcome this interference, while the EEE PC doesn't.

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• Extract part of a image from a big image

  - by rajat

  I have a 6 images , and each image has a certain section that i want to save as a separate image , the problem is that it has to be accurate because i am doing some animation using the sub-image so they should exactly . so I want to accurately extract a that part from each of the 6 images , i can't do it using a image editor in which i have to make the bounding box myself because it will not be accurate , is there any program that lets me do this by like defining a box using numerical values. PS: I don't want to write matlab or opencv program for this .

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• Set an Excel cell's color based on multiple other cells' colors

  - by Lord Torgamus

  I have an Excel 2007 spreadsheet for a list of products and a bunch of factors to rate each one on, and I'm using Conditional Formatting to set the color of the cells in the individual attribute columns. It looks something like this: I want to fill in the rating column for each item with a color, based on the color ratings of its individual attributes. Examples of ways to determine this: the color of the category in which the item scored worst the statistical mode of the category colors the average of the category ratings, where each color is assigned a numerical value How can I implement any or all of the above rules? (I'm really just asking for a quick overview of the relevant Excel feature; I don't need step-by-step instructions for each rule.)

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• What's the advantage of using a bash script for cron jobs?

  - by AlxVallejo

  From my understanding you can write your crons by editing crontab -e I've found several sources that instead refer to a bash script in the cron job, rather than writing a job line for line. Is the only benefit that you can consolidate many tasks into one cron job using a bash script? Additional question for a newbie: Editing crontab -e refers to one file correct? I've noticed that if I open crontab -e and close without editing, when I open the file again there is a different numerical extension such as: "/tmp/crontab.XXXXk1DEaM" 0L, 0C I though the crontab is stored in /var/spool/cron or /etc/crontab ?? Why would it store the cron in the tmp folder?

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• Asterisk Register username with special character like "@"

  - by Najibul Huq

  I am using a SIP provider that has provided me with a username like: [email protected] (Note this is only the username part) And has a numerical password. My Register string looks something like this: [email protected]:[email protected] But this is not working, as asterisk is only sending the first part +112223344 before the first @. My provider is adamant about having the full form of it. This is the first time I am facing this issue that is quite unusual for me. Please help.

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