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  • how to match a regulas expresion like (%i1) in python pexpect

    - by mike
    I want to use maxima from python using pexpect, whenever maxima starts it will print a bunch of stuff of this form: $ maxima Maxima 5.27.0 http://maxima.sourceforge.net using Lisp SBCL 1.0.57-1.fc17 Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) i would like to start up pexpect like so: import pexpect cmd = 'maxima' child = pexpect.spawn(cmd) child.expect (' match all that stuff up to and including (%i1)') child.sendline ('integrate(sin(x),x)') chil.expect( match (%o1 ) ) print child.before how do i match the starting banner up to the prompt (%i1)? and so on, also maxima increments the (%i1)'s by one as the session goes along, so the next expect would be: child.expect ('match (%i2)') child.sendline ('integrate(sin(x),x)') chil.expect( match (%o2 ) ) print child.before how do i match the (incrementing) integers?

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  • Which python mpi library to use?

    - by Dana the Sane
    I'm starting work on some simulations using MPI and want to do the programming in Python/scipy. The scipy site lists a number of mpi libraries, but I was hoping to get feedback on quality, ease of use, etc from anyone who has used one.

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  • Will these optimizations to my Ruby implementation of diff improve performance in a Rails app?

    - by grg-n-sox
    <tl;dr> In source version control diff patch generation, would it be worth it to use the optimizations listed at the very bottom of this writing (see <optimizations>) in my Ruby implementation of diff for making diff patches? </tl;dr> <introduction> I am programming something I have never done before and there might already be tools out there to do the exact thing I am programming but at this point I am having too much fun to care so I am still going to do it from scratch, even if there is a tool for this. So anyways, I am working on a Ruby on Rails app and need a certain feature. Basically I want each entry in a table of mine, let's say for example a table of video games, to have a stored chunk of text that represents a review or something of the sort for that table entry. However, I want this text to be both editable by any registered user and also keep track of different submissions in a version control system. The simplest solution I could think of is just implement a solution that keeps track of the text body and the diff patch history of different versions of the text body as objects in Ruby and then serialize it, preferably in human readable form (so I'll most likely use YAML for this) for editing if needed due to corruption by a software bug or a mistake is made by an admin doing some version editing. So at first I just tried to dive in head first into this feature to find that the problem of generating a diff patch is more difficult that I thought to do efficiently. So I did some research and came across some ideas. Some I have implemented already and some I have not. However, it all pretty much revolves around the longest common subsequence problem, as you would already know if you have already done anything with diff or diff-like features, and optimization the function that solves it. Currently I have it so it truncates the compared versions of the text body from the beginning and end until non-matching lines are found. Then it solves the problem using a comparison matrix, but instead of incrementing the value stored in a cell when it finds a matching line like in most longest common subsequence algorithms I have seen examples of, I increment when I have a non-matching line so as to calculate edit distance instead of longest common subsequence. Although as far as I can tell between the two approaches, they are essentially two sides of the same coin so either could be used to derive an answer. It then back-traces through the comparison matrix and notes when there was an incrementation and in which adjacent cell (West, Northwest, or North) to determine that line's diff entry and assumes all other lines to be unchanged. Normally I would leave it at that, but since this is going into a Rails environment and not just some stand-alone Ruby script, I started getting worried about needing to optimize at least enough so if a spammer that somehow knew how I implemented the version control system and knew my worst case scenario entry still wouldn't be able to hit the server that bad. After some searching and reading of research papers and articles through the internet, I've come across several that seem decent but all seem to have pros and cons and I am having a hard time deciding how well in this situation that the pros and cons balance out. So are the ones listed here worth it? I have listed them with known pros and cons. </introduction> <optimizations> Chop the compared sequences into multiple chucks of subsequences by splitting where lines are unchanged, and then truncating each section of unchanged lines at the beginning and end of each section. Then solve the edit distance of each subsequence. Pro: Changes the time increase as the changed area gets bigger from a quadratic increase to something more similar to a linear increase. Con: Figuring out where to split already seems like you have to solve edit distance except now you don't care how it is changed. Would be fine if this was solvable by a process closer to solving hamming distance but a single insertion would throw this off. Use a cryptographic hash function to both convert all sequence elements into integers and ensure uniqueness. Then solve the edit distance comparing the hash integers instead of the sequence elements themselves. Pro: The operation of comparing two integers is faster than the operation of comparing two strings, so a slight performance gain is received after every comparison, which can be a lot overall. Con: Using a cryptographic hash function takes time to convert all the sequence elements and may end up costing more time to do the conversion that you gain back from the integer comparisons. You could use the built in hash function for a string but that will not guarantee uniqueness. Use lazy evaluation to only calculate the three center-most diagonals of the comparison matrix and then only calculate additional diagonals as needed. And then also use this approach to possibly remove the need on some comparisons to compare all three adjacent cells as desribed here. Pro: Can turn an algorithm that always takes O(n * m) time and make it so only worst case scenario is that time, best case becomes practically linear, and average case is somewhere between the two. Con: It is an algorithm I've only seen implemented in functional programming languages and I am having a difficult time comprehending how to convert this into Ruby based on how it is described at the site linked to above. Make a C module and do the hard work at the native level in C and just make a Ruby wrapper for it so Ruby can make all the calls to it that it needs. Pro: I have to imagine that evaluating something like this in could be a LOT faster. Con: I have no idea how Rails handles apps with ruby code that has C extensions and it hurts the portability of the app. This is an optimization for after the solving of edit distance, but idea is to store additional combined diffs with the ones produced by each version to make a delta-tree data structure with the most recently made diff as the root node of the tree so getting to any version takes worst case time of O(log n) instead of O(n). Pro: Would make going back to an old version a lot faster. Con: It would mean every new commit, the delta-tree would get a new root node that will cost time to reorganize the delta-tree for an operation that will be carried out a lot more often than going back a version, not to mention the unlikelihood it will be an old version. </optimizations> So are these things worth the effort?

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  • Unique identifiers for users

    - by Christopher McCann
    If I have a table of a hundred users normally I would just set up an auto-increment userID column as the primary key. But if suddenly we have a million users or 5 million users then that becomes really difficult because I would want to start becoming more distributed in which case an auto-increment primary key would be useless as each node would be creating the same primary keys. Is the solution to this to use natural primary keys? I am having a real hard time thinking of a natural primary key for this bunch of users. The problem is they are all young people so they do not have national insurance numbers or any other unique identifier I can think of. I could create a multi-column primary key but there is still a chance, however miniscule of duplicates occurring. Does anyone know of a solution? Thanks

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  • unit, integration and system tests for PHP applications

    - by Sara
    Hi, We were given an assignment to develop a prototype for a customer community. It was suggested PHP as the programming language. (but we're not supposed to actually code it, just a prototype with documentation is required) I'm wondering what are the best practices/ tools used in Unit testing, Integration Testing and System testing for such a php app Thanks

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  • Alternatives to fread and fwrite for use with structured data

    - by forest58
    The book Beginning Linux Programming (3rd ed) says "Note that fread and fwrite are not recommended for use with structured data. Part of the problem is that files written with fwrite are potentially nonportable between different machines." What does that mean exactly? What calls should I use if I want to write a portable structured data reader or writer? Direct system calls?

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  • C# asynchronous beginsend method

    - by Jatin
    I am a newbie in socket programming. I am developing a server client application. And I am using Asynchronous tcp ip socket. But now I am facing a problem. In my client side I am receiving my data by a 2kb byte array by beginReceive method. Its working perfectly if data size below or equals to 2 kb, but problem occurring when data size exceeding 2kb range. Please give me some solution.

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  • developer tools for os' other than windows

    - by user225269
    I currently use visual studio 2008 for creating projects that can run on windows. Can you recommend me of other tools that can be used to develop applications for other operating systems?(Linux, Mac, Solaris) The most prominent programming languages will do(C++, C#, F#) And scripting languages(PHP, Perl, etc)

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  • In Rails: How can I turn off caching for a particular activerecord database table?

    - by pmneve
    I have an associative table (scripts_runs) (has_many, through) that carries a status column ('started', 'ready to parse', 'completed' ). The started and ready to parse states are signaled by 'flag' files from distributed executions of the scripts pickedup periodically (20 seconds). The completed status is written directly to the associative table by the parser when it is done. With short scripts the complete status is written before the ready to parse flag file is picked up. Because the row from the table is cached, the complete status is not seen by the observer for the flag files and gets overwritten by the ready to parse status. This is not good. I need the status to be updated in the database in the correct sequence so an Ajax periodic query can inform the user of the status of each script and when the run ( consisting of one to many scripts ) is completed. Can I force the ScriptRun.find(:id) to always go to the database? If so how? If not, why not???

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  • Classic assembly language texts not using x86?

    - by wrp
    I'm looking for texts that give detailed treatment of assembly programming principles and don't use x86 as the target architecture. I haven't found any recent books like that, but I would expect that there were some good ones written in the 1970s and 1980s, when whole applications were still written in assembly. The architecture used should also be one of the cleaner designs, such as the 6502 or VAX.

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  • What is your laptop's display size?

    - by grigy
    I want to get a new laptop and not sure what display size is the optimal. I need it for programming while I'm traveling. So the balance is between portability and usability. My old laptop is 15.4" and I think it's big and heavy for travel.

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  • Java MouseListener

    - by ikurtz
    I have a bunch of JLabels and i would like to trap mouse click events. at the moment i am having to use: public void mouseClicked(MouseEvent arg0) { } public void mouseExited(MouseEvent arg0) { } public void mouseEntered(MouseEvent arg0) { } public void mousePressed(MouseEvent arg0) { } public void mouseReleased(MouseEvent arg0) { System.out.println("Welcome to Java Programming!"); } I was wondering if there is a tidier way of doing this instead of having a bunch of events I do not wish trap?

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  • server|configuration problem, a php script just die with no error log & no reason

    - by Roberto
    Hi (first of all, thanks for your attention & sorry for my bad english hahaha also this is not a programming error, or thats what I think, I think this is an error in some configuration of the server or something else but I dont know what) I have a php script (is running like a process of linux, its not running on the web browser) that send SMS via SMPP on the port 2055 (using sockets in php) & then inserts like 10,000 rows into a dababase on MySQL, the script gets the data from a XML file; firts it was running in a shared server (Hostgator is our hosting provider) & at the begining it worked fine, with no trouble, but 5 months later an error appear, the process just die with no reason, the script only sent & inserted 700 rows in the table of the database & the process didnt show any warning or error, nothing appears in the error logs, & I didnt make any change in the script Hostgator never helped us hahaha so we decided to move the script from the shared server to a dedicated server; I thought it was a memory problem or something like that, but when we move the script to the dedicated server the problem just get worse, the script die when has just sent & inserted 40 to 50 rows to the database the information about this error: the shared server is on Red Hat 4.1.2-46 & the dedicated server is on CentOS 5.4 I have commented the line that sends the SMS, & the problem remains in the shared server, at the begining the script was fine, but then the script started to die when has just inserted 700 aprox. in the database, & now the script is dying when has inserted 2500 rows, its better but we didnt change anything in the dedicated server, the script dies when has just inserted like 40 row in the table the script, before it dies, change to a zombie process & we dont know why the usage of memory appears to be 0.3%, and of the cpu appears to be 0.7% to 1% I have changed the max memory limit of php to 128Mb, and even to -1 (so php wont have any limit) but the problem remains we have the limit of 50 connections of mysql at the same time, so I think this is not the problem Im using mysqli to connect from php to mysql Hostgator report that they haven't made any change or update in the servers what could be the problem?? what should I do??? what should I search??? is something in the logic Im missing?? what steps do I have to follow when managing & searching problems of process on Linux??? thank you very much, I think this is not a programming problem, but you have more experience than me, you can tell me thanks!!! bye!!! :)

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  • first app - wrong language is shown in appstore

    - by Sean
    hi all last week i distributed my first app to the appstore. what i've to see was, that the app language which is shown in appstore is not the right one. my app is just in german, but in appstore english is shown up. can somebody tell me what i've exactly got to do, that the language in the appstore is german? i know i ned a "de.lproj" folder, but i don't know what this folder should contain and what i've got to do step by step to realize that the right way. thanks in advance sean

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  • Is there a way to avoid debugger?

    - by Gabriel Šcerbák
    I don't like debugging in a debugger, because I think it is often below the abstraction layer of the programming language and it is often not reproducible. I favor usign unit tests when possible and I think they are a good way, but it is not always that easy to implement them. Do you know about any other alternative approaches to avoid the use of debugger?

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  • How do you handle files that can't support concurrent edits in Mercurial?

    - by Scott Whitlock
    I'm using Mercurial with TortoiseHg. Each developer has their own repositories, and there's one central repository on the server for synchronizing our changes. (This will sound lame, but we're using it to manage the source for a legacy VB6 project. Nothing we can do about that...) As has been pointed out elsewhere, there is a big problem in VB6 with merging the .frx (form resources) files. So code changes seem to merge fine, but if two developers both make changes at the same time in the form design view, we can't merge. I'm ok with disallowing concurrent edits, but of course the whole point of Mercurial is that it's distributed so there is no option to force a file to be locked before editing. I don't believe there's a Mercurial solution for this, so I'm wondering: other developers who are using Mercurial for version control, do you have some 3rd party tool that assists with locking files for editing in the cases where it's necessary? Did we make a mistake using Mercurial instead of something like SVN?

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  • Difference Between Property And Function.

    - by Asim Sajjad
    Which one is better to use when it come to return value for example public int EmployeeAge { get{return intEmployeeAge}; } And public int EmployeeAge() { return intEmployeeAge; } Which one is better and why? And what is best programming practice to use when we have secnario like above ?

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