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• Looking for calculator source code, BSD-licensed

  - by Horace Ho

  I have an urgent project which need many functions of a calculator (plus a few in-house business rule formulas). As I won't have time to re-invent the wheel so I am looking for source code directly. Requirements: BSD licensed (GPL won't help) in c/c++ programming language 32-bit CPU minimum dependency on platform API/data structure best with both RPN and prefix notation supported emulator/simulator code also acceptable (if not impossible to add custom formula) with following functions (from wikipedia) Scientific notation for calculating large numbers floating point arithmetic logarithmic functions, using both base 10 and base e trigonometry functions (some including hyperbolic trigonometry) exponents and roots beyond the square root quick access to constants such as pi and e plus hexadecimal, binary, and octal calculations, including basic Boolean math fractions optional statistics and probability calculations complex numbers programmability equation solving

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• Distinction between an extranet and a DMZ

  - by Markus Yrjölä

  I've been reading about intranets, extranets, DMZs and VPNs now, and I'd need some clarifications related to extranets and DMZs. I understand that they are different types of concepts - extranet allows limited access to some intranet resources, while DMZ is a subnet that sits between the internet and intranet and hosts the external-faced services. However, I'd like to know what is their distinction in practice in a usual setup? The Wikipedia article on extranets says that extranets are similar to DMZs because they are used for the same purpose (providing access to some services/resources without exposing the whole intranet). The article also states that an extranet is a part of a VPN, and this TechNet article also states that extranet access is often implemented similarly to remote intranet access, e.g. with a VPN. The TechNet article also says that commonly the extranet is hosted inside the DMZ. This Pearson article says "Although [the DMZ] is technically located within the intranet, [it] can serve as the extranet as well". This is slightly confusing. Consider this scenario: A company has a B2C website hosted in the DMZ. The website can be accessed from anywhere, but requires user authentication. The underlying web app has its database inside the intranet and also interacts with some web services that are hosted inside the intranet (i.e. it accesses intranet resources). The way I see it, the website does effectively offer a restricted access to the intranet. But can it be considered an extranet? If we take the Wikipedia definition of an extranet literally - "An extranet is a computer network that allows controlled access from outside of an organization's intranet" - I think it can. Let's say that the above can't be considered an extranet. What if we change the scenario slightly, and say it's a B2B website, where the access is e.g. limited to connections coming from a specific business partner (by using site-to-site VPN, for example). In this case it surely is an extranet, right? If this is the case, then the difference between extranet services and any other services hosted in the DMZ is simply access restrictions?

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• A strong case for WF

  - by Pita.O

  Hi guys, I have struggled for so long to find a compelling use case for workflow (ie: WF) as against regular imperative programming. Each time I fall back to the conclusion that I should just leave WF out or defer getting into it until later. But I keep having this nagging feeling that there's something am missing. Does anyone know any book that truly makes a strong case for the Workflow way? The book has to (i) teach WF well, and (ii) show using appropriate use cases that WF made an implementation easy to do than if we just did our regular straight coding. I will appreciate it.

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• Email sent by ActionMailer is taking six hours to deliver mail.

  - by grg-n-sox

  So I have been asked to help maintain a website that uses Ruby on Rails. Now, let me just say I've been programming Ruby for awhile but I am still new to Rails. The first problem brought to my attention is how the activation email takes about six hours to arrive. It would be one thing if the email was not being sent due to errors but it is being send correctly, just slow. Also the server this is running on is also its own SMTP. I checked how the email was being formatted before calling the setup_email method and everything looks okay. I even dug into the ActionMailer lib and read through the files there and didn't see anything out of the ordinary. So what is most likely causing the email to take six hours to deliver?

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• iPhone Foundation - performance implications of mutable and xxxWithCapacity:0

  - by Adam Eberbach

  All of the collection classes have two versions - mutable and immutable, such as NSArray and NSMutableArray. Is the distinction merely to promote careful programming by providing a const collection or is there some performance hit when using a mutable object as opposed to immutable? Similarly each of the collection classes has a method xxxxWithCapacity, like [NSMutableArray arrayWithCapacity:0]. I often use zero as the argument because it seems a better choice than guessing wrongly how many objects might be added. Is there some performance advantage to creating a collection with capacity for enough objects in advance? If not why isn't the function something like + (id)emptyArray?

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• Usng Rails ActiveRecord relationships

  - by Brian Goff

  I'm a newbie programmer, been doing shell scripting for years but have recently taken on OOP programming using Ruby and am creating a Rails application. I'm having a hard time getting my head wrapped around how to use my defined model relationships. I've tried searching Google, but all I can come up with are basically cheat sheets for what has_many, belongs_to, etc all mean. This stuff is easy to define & understand, especially since I've done a lot of work directly with SQL. What I don't understand is how to actually used those defined relationships. In my case I have 3 models: Locations Hosts Services Relationships (not actual code, just for shortening it): Services belongs_to :hosts Hosts has_many :services belongs_to :locations Locations has_many :hosts In this case I want to be able to display a column from Locations while working with Services. In SQL this is a simple join, but I want to do it the Rails/Ruby way, and also not use SQL in my code or redefine my joins.

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• Why can't I download a whole image file with urllib2.urlopen()

  - by John Gann

  When I run the following code, it only seems to be downloading the first little bit of the file and then exiting. Occassionally, I will get a 10054 error, but usually it just exits without getting the whole file. My internet connection is crappy wireless, and I often get broken downloads on larger files in firefox, but my browser has no problem getting a 200k image file. I'm new to python, and programming in general, so I'm wondering what nuance I'm missing. import urllib2 xkcdpic=urllib2.urlopen("http://imgs.xkcd.com/comics/literally.png") xkcdpicfile=open("C:\\Documents and Settings\\John Gann\\Desktop\\xkcd.png","w") while 1: chunk=xkcdpic.read(4028) if chunk: print chunk xkcdpicfile.write(chunk) else: break

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• Touchscreen using sound input?

  - by ricardowong

  Hi, i don't really know if it is actually possible, but i believe that it can be made. How possible is it to make a program that recognizes different sound bouncing from the screen and turn it into a position that will obviously be later fed to the mouse. I know that it sounds kind of dumb, but lately i've been noticing that a very dull, strong sound is made when touching the screen, and that sound varies when doing so at different positions. Probably the microphone "hears" differently because the screen acts as a drum with the casing. Anyways, what do you think, anyone has any experience programming with sound?

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• Distributing APNS providers

  - by Sam

  I'm writing a business-focused iPhone app which includes a self-hosted server component. I'd like to include push notification functionality in the server; reading through the programming guide it looks as if this would involve either: Distributing the provider certificate with the server component - this doesn't sound like a terribly good idea (even if Apple permits it?) Hosting a shared notification provider and forwarding notifications to APNS from the servers. For an ongoing, high-availability service, this is likely to require including a subscription pricing component, which I would prefer to avoid. Require customers to apply for their own provider certificate. However, it's not clear whether multiple organisations are allowed to apply for provider certificates with a single bundle ID, and it would significantly increase the barrier to adoption. APNS looks to me as if it's specifically geared for centrally hosted services. Is anyone distributing self-hosted notification providers? Are there any other options?

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• displaying web pages over web views in collection view using cocoa bindings

  - by Miraaj

  Hi all, I tried sample example given at this link - Collection View Programming Guide It is simple and it worked. Considering it as a reference I tried a simple application which will show a collection view of web views with some web page displayed over each web view. The model class has two properties: NSString *pageName, and NSURL *pageURL. I then followed each and every step written in tutorial above with required modifications but I was caught in the step - How to bind web view to collection view item? In binding tab it shows three possibilities : Editable, Hidden, Tool tip but none of these is working. Can anyone suggest me way to accomplish my requirement? Thanks, Miraaj

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• help installing odfWeave

  - by Andreas

  This is not a programming question per se - but I hope someone can help: I can't install odfWeave - it looks like the problem is with the package XML - which i can't install either. checking for xml2-config... no Cannot find xml2-config ERROR: configuration failed for package ‘XML’ * removing ‘/home/andreas/R/i486-pc-linux-gnu-library/2.10/XML’ * installing source package ‘odfWeave’ ... ** R ** inst ** preparing package for lazy loading Warning in library(pkg, character.only = TRUE, logical.return = TRUE, lib.loc = lib.loc) : there is no package called 'XML' Error : package 'XML' could not be loaded ERROR: lazy loading failed for package ‘odfWeave’ * removing ‘/home/andreas/R/i486-pc-linux-gnu-library/2.10/odfWeave’ Any help much appreciated System: ubuntu 9.04

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• Looking for programs on audio tape/cassette containing programs for Sinclair Z80 PC?

  - by DVK

  OK, so back before ice age, I recall having a Sinclair ZX80 PC (with TV as a display, and a cassette tape player as storage device). Obviously, the programs on cassette tapes made a very distinct sound (er... noise) when playing the tape... I was wondering if someone still had those tapes? The reason (and the reason this Q is programming related) is that IIRC different languages made somewhat different pitched noises, but I would like to run the tape and listen myself to confirm if that was really the case...

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• Calculating determinant by hand

  - by ldigas

  Okey, this is only half programming, but let's see how you are on terms with manual calculations. I believe many of you did this on your university's while giving "linear systems" ... the problem is it's been so long I can't remember how to do it any more. I know quite a few algorithms for calculating determinants, and they all work fine ... for large systems, where one would never try to do it manually. Unfortunatelly, I'm soon going on an exam, where I do have to calculate it manually, up to the system of 5. So, I have a K(omega) matrix that looks like this: [2-(omega^2)*c -4 2 0 0] [-2 5-(omega^2)*c -4 1 0] [1 -4 6-(omega^2)*c -4 1] [0 1 -4 5-(omega^2)*c -2] [0 0 2 -4 2-(omega^2)*c] and I need all the omegas which satisfy the det[K(omega)]=0 criteria. What would be a good way to calculate it so it can be repeated in a manual process ?

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• Language/tech specific books which improve vendor-neutral development skills

  - by dotnetdev

  If I ask what the following books have in common: "Accelerated C# 2010, C# in Depth, Pro C# 2008", the answer would be that they would help me to improve my understanding of C# and secondly, my general coding skills. What language-specific/tech-specific books (like those named above) would teach me a great deal about general programming techniques and good habits? I'm thinking Java books would be very good for me (I code in C# primarily), as both these languages are similar and so I am sure that specialist books on Java threading, performance tuning, etc, can be applied to C# (not all 100% content of a Java book). Thanks

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• posix pthreads in c

  - by Codenotguru

  Iam new to c programming and needs some help. long *taskids[NUM_THREADS]; for(t=0; t<NUM_THREADS; t++) { taskids[t] = (long *) malloc(sizeof(long)); *taskids[t] = t; printf("Creating thread %ld\n", t); rc = pthread_create(&threads[t], NULL, PrintHello, (void *) taskids[t]); ... } This code fragment demonstrates how to pass a simple integer to each thread. The calling thread uses a unique data structure for each thread, insuring that each thread's argument remains intact throughout the program. Iam not able to understand how this is happening can somebody explain it??

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• Android WakeLock and KeyGuard

  - by KimAMartinsen

  Hi! I'm just wondering if I do this correctly; I'm programming a notification app which can display a notification when the phone is sleeping Disable keyguard lock Aquire a wake lock show notification Set alarm for timeout and reenabling keyguard and release wakelock is the user dont touches the screen. 4.1 User touches the screen, and I disable the timer. Do nothing more. Done and done 4.2 User dont touch the screen, so reenable keyguard and release wakelock. Phone sleeps again Basically I'm wondering about point 4.1 the most. cancel the pendingintent for the alarm, and do nothing more? or should the keyguard and wakelock that are set be dealt with in some way?

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• Storing and comparing biometric information

  - by Chathuranga Chandrasekara

  I am not sure whether this is the best place to post this. But this is strongly related with programming so decided to put this here. In general we use biometrics in computer applications say for authentication. Lets get 2 examples finger prints and facial recognition. In those cases how we keep the information for comparison. As an example we can't keep a image and process it every time. So what are the methodologies we use to store/determine the similarity in such cases? Are there any special algorithms that designed for that purposes.? (Ex : To return a approximately equal value for a finger print of a certain person every time)

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• How to check misspelled email during user registration

  - by Nulldevice

  I use an email registration and confirmation in my project (yes, I know about OpenID. In my counry, a main email service lack it). Sometimes users misspell their email addresses. I know about this due to "message could not be delivered" letters in a mailbox. A misspelled address is absolutely correct, because I check it with a regular expression - say, [email protected] intstead of [email protected]. And I do not want to duplicate a email field in a registration form (who likes it?). Request processing routine cannot wait for email delivery - it could take an unpredictable time. So, my script will return to user a confirmation message "An email was sent". And the user will wait for it forever (of cause, not - he/she will turn to an alternative project with a more perfect registration system). Does someone knows how it can be improved (in any programming language)?

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• What's the best way to explain parsing to a new programmer?

  - by Daisetsu

  I am a college student getting my Computer Science degree. A lot of my fellow students really haven't done a lot of programming. They've done their class assignments, but let's be honest here those questions don't really teach you how to program. I have had several other students ask me questions about how to parse things, and I'm never quite sure how to explain it to them. Is it best to start just going line by line looking for substrings, or just give them the more complicated lecture about using proper lexical analysis, etc. to create tokens, use BNF, and all of that other stuff? They never quite understand it when I try to explain it. What's the best approach to explain this without confusing them or discouraging them from actually trying.

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• Forbidden Not authorized to access this feed

  - by user302593

  Hai, I want to create a sites by using java programming. but it contain error like this... Exception in thread "main" com.google.gdata.util.ServiceForbiddenException: Forbidden Not authorized to access this feed at com.google.gdata.client.http.HttpGDataRequest.handleErrorResponse(HttpGDataRequest.java:561) at com.google.gdata.client.http.GoogleGDataRequest.handleErrorResponse(GoogleGDataRequest.java:563) at com.google.gdata.client.http.HttpGDataRequest.checkResponse(HttpGDataRequest.java:536) at com.google.gdata.client.http.HttpGDataRequest.execute(HttpGDataRequest.java:515) at com.google.gdata.client.http.GoogleGDataRequest.execute(GoogleGDataRequest.java:535) at com.google.gdata.client.Service.getFeed(Service.java:1073) at com.google.gdata.client.Service.getFeed(Service.java:936) at com.google.gdata.client.GoogleService.getFeed(GoogleService.java:631) at com.google.gdata.client.Service.getFeed(Service.java:955) at lsites.getSiteFeed(lsites.java:25) at lsites.main(lsites.java:40) what i want to do? Regards, Bhuvana

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• How to sketch out an event-driven system?

  - by Jordan

  I'm trying to design a system in Node.js (an attempt at solving one of my earlier problems, using Node's concurrency) but I'm running into trouble figuring out how to draw a plan of how the thing should operate. I'm getting very tripped up thinking in terms of callbacks instead of returned values. The flow isn't linear, and it's really boggling my ability to draft it. How does one draw out an operational flow for an event-driven system? I need something I can look at and say "Ok, yes, that's how it will work. I'll start it over here, and it will give me back these results over here." Pictures would be very helpful for this one. Thanks. Edit: I'm looking for something more granular than UML, specifically, something that will help me transition from a blocking and object-oriented programming structure, where I'm comfortable, to a non-blocking and event driven structure, where I'm unfamiliar.

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• How to write Asynchronous LINQ query?

  - by Morgan Cheng

  After I read a bunch of LINQ related stuff, I suddenly realized that no articles introduce how to write asynchronous LINQ query. Suppose we use LINQ to SQL, below statement is clear. However, if the SQL database responds slowly, then the thread using this block of code would be hindered. var result = from item in Products where item.Price > 3 select item.Name; foreach (var name in result) { Console.WriteLine(name); } Seems that current LINQ query spec doesn't provide support to this. Is there any way to do asynchronous programming LINQ? It works like there is a callback notification when results are ready to use without any blocking delay on I/O.

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• Communicating with the PC via USB connection in Android

  - by Danny Singh

  I'm fairly new to android programming and need some information for a 4th year forensics course project. Basically I am trying to create a suite of tools for live analysis of an android phone. I know how to get the information I need on the phone, but I was wondering if there was a way to communicate that information back to the PC? I want to be able to run a program from a PC, which, when the phone is docked, will allow the user to access information about the phone (ie currently running services/processes, bluetooth/wifi connections, etc). I have a bunch of methods that will run on the phone and get all the information, but I want to be able to call those methods from the PC, execute on the phone, then have the information sent back to the PC to display to the user instead of just displaying it on the phone. This is to leave as small a footprint on the phone as possible. Thanks a lot.

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• Visual Studio 2010 Extensibility, MPF and language services

  - by MainMa

  Hi, I am trying to extend Visual Studio 2010 RC to be able to use a custom programming language. The first two things I've tried to do is a syntax highlight/Intellisense feature (easily done, thanks to "Ook!" sample from PDC09) and a possibility to create new project templates (i.e. be able to open *.myproj files). For this second task, I can't find any easy tutorials or samples. Most samples are for Visual Studio 2008 (as for IronPython integration) or even VS2003. The few samples available for VS2010 do not work (including MPFProj) or do not compile, and are too hard to understand. Is there any easy-to-understand sample, either using MPFProj or a standalone solution, showing how to integrate templates for a custom language inside Visual Studio 2010?

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• What technical skills needed for algorithmic trading, HFT, etc?

  - by alchemical

  I'm interested in getting into developing trading systems, black box, HFT, etc. My primary experience is with C# and .Net (7 years). I've also done some sockets programming. I have some experience in finance working on analysis applications (2 years). My goal is to move into developing automated trading systems for a hedge fund, bank, etc. Is there any way to learn the skills needed for this without somehow getting the job first? I've looked at the open source tradelink, IB interactive brokerage, etc. I'm playing around with this framework, and may hook it up and do some paper trading. However, I'm not sure if this has much relationship with how a well-funded entity would be conducting a high-level automated trading operation. I.e. would the tools and frameworks they prefer be a totally different skill-set? Also wondering if I need to learn C++ and/or Java for these types of apps.

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