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Articles indexed Sunday May 9 2010

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  • Parsing basic math equations for children's educational software?

    - by Simucal
    Inspired by a recent TED talk, I want to write a small piece of educational software. The researcher created little miniature computers in the shape of blocks called "Siftables". [David Merril, inventor - with Siftables in the background.] There were many applications he used the blocks in but my favorite was when each block was a number or basic operation symbol. You could then re-arrange the blocks of numbers or operation symbols in a line, and it would display an answer on another siftable block. So, I've decided I wanted to implemented a software version of "Math Siftables" on a limited scale as my final project for a CS course I'm taking. What is the generally accepted way for parsing and interpreting a string of math expressions, and if they are valid, perform the operation? Is this a case where I should implement a full parser/lexer? I would imagine interpreting basic math expressions would be a semi-common problem in computer science so I'm looking for the right way to approach this. For example, if my Math Siftable blocks where arranged like: [1] [+] [2] This would be a valid sequence and I would perform the necessary operation to arrive at "3". However, if the child were to drag several operation blocks together such as: [2] [\] [\] [5] It would obviously be invalid. Ultimately, I want to be able to parse and interpret any number of chains of operations with the blocks that the user can drag together. Can anyone explain to me or point me to resources for parsing basic math expressions? I'd prefer as much of a language agnostic answer as possible.

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  • Python references

    - by hekevintran
    Can someone explain why the example with integers results in different values for x and y and the example with the list results in x and y being the same object? x = 42 y = x x = x + 1 print x # 43 print y # 42 x = [ 1, 2, 3 ] y = x x[0] = 4 print x # [4, 2, 3] print y # [4, 2, 3] x is y # True

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  • jquery simplemodal close wont work in firefox

    - by junkqwe
    I am using jquery.simplemodal 1.3.5 (i tried older versions) the close button doesnt close the modal in firefox (i tried IE and it work fine) this is the test page i am using: <html> <head> <title>Untitled Page</title> <style> #simplemodal-overlay { background-color:#000; cursor:wait; } #simplemodal-container a.modalCloseImg { background: url(../images/modal_close.png) no-repeat; width:25px; height:29px; display:inline; z-index:3200; position:absolute; top:15px; right:18px; cursor:pointer; } .modala { width: 372px; height: 206px; background: url(../images/modal.png) no-repeat; } </style> </head> <body> test page <script language="javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js" type="text/javascript"></script> <script language="javascript" src="/include/jquery.simplemodal-1.3.5.js" type="text/javascript"></script> <script type="text/javascript"> $("body").click(function() { $.modal("<div class=\"modala\"><h1>SimpleModal</h1></div>", {overlayClose: true} ); }); </script> </body> </html> what can be the problem? is it a known problem with simplemodal and FF?

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  • Virtualmin - Domain / Subdomain confusion

    - by Dan
    Hi, I've just purchased a new VPS and setup Virtualmin on it. I pointed my domain at the IP of the server and set up a new virtual server through Virtualmin. I uploaded a simple php script to check it was working and it seemed to be fine. I then created a subserver and also pointed test.mydomain.com to my IP, with the intension of having mydomain.com and test.mydomain.com both pointing to different directories on my VPS. However, once I added the subserver, I received a 403 Forbidden message if I tried to access either the new subdomain OR the existing site. I uploaded a similar php script to the subfolder and it then displayed correctly. However, I now get sent to the same script regardless of what URL I type in. I did try posting this message on the Virtualmin forum, but their filters picked it up as spam and wouldn't allow it. Can anyone help me? I'm sure it's just something simple, but this is driving me crazy! Any advice appreciated. Thanks.

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  • Ruby on rails active-record generated SQL on Postgres

    - by jpartogi
    Dear all, Why does Ruby on rails generated more queries in the background on Postgres than MySQL? I haven't tried deploying Rails on production with Postgres yet, but I am just afraid this generated queries would affect the performance. Do you find Rails with Postgres is slower than MySQL, knowing that it produce more query on the background? Or it is relatively the same?

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  • Minimum cost strongly connected digraph

    - by Kazoom
    I have a digraph which is strongly connected (i.e. there is a path from i to j and j to i for each pair of nodes (i, j) in the graph G). I wish to find a strongly connected graph out of this graph such that the sum of all edges is the least. To put it differently, I need to get rid of edges in such a way that after removing them, the graph will still be strongly connected and of least cost for the sum of edges. I think it's an NP hard problem. I'm looking for an optimal solution, not approximation, for a small set of data like 20 nodes. Edit A more general description: Given a grap G(V,E) find a graph G'(V,E') such that if there exists a path from v1 to v2 in G than there also exists a path between v1 and v2 in G' and sum of each ei in E' is the least possible. so its similar to finding a minimum equivalent graph, only here we want to minimize the sum of edge weights rather than sum of edges. Edit: My approach so far: I thought of solving it using TSP with multiple visits, but it is not correct. My goal here is to cover each city but using a minimum cost path. So, it's more like the cover set problem, I guess, but I'm not exactly sure. I'm required to cover each and every city using paths whose total cost is minimum, so visiting already visited paths multiple times does not add to the cost.

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  • How is the presentation layer of a CALayer generated?

    - by KJ
    Hi, I'm having difficulties animating my custom layer property using Core Anmiation. My question is how the presentation of a CALayer is generated. Here is what I have now: @interface MyLayer : CALayer { NSMutableDictionary* customProperties; } @property (nonatomic, copy) NSMutableDictionary* customProperties; @end And when I try to animate the key path "customProperties.roll" using CABasicAnimation and addAnimation:forKey:, it seems that the customProperties variable doesn't get copied from the model layer to the presentation layer, and the customProperties of the presentation layer appears to be nil, failing to update the value for the key "roll". Is there a way to animate values in a dictionary correctly? What is the exact relationship between a model layer and a presentation layer while being animated? Thanks!

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  • Python Imaging: YCbCr problems

    - by daver
    Hi, I'm doing some image processing in Python using PIL, I need to extract the luminance layer from a series of images, and do some processing on that using numpy, then put the edited luminance layer back into the image and save it. The problem is, I can't seem to get any meaningful representation of my Image in a YCbCr format, or at least I don't understand what PIL is giving me in YCbCr. PIL documentation claims YCbCr format gives three channels, but when I grab the data out of the image using np.asarray, I get 4 channels. Ok, so I figure one must be alpha. Here is some code I'm using to test this process: import Image as im import numpy as np pengIm = im.open("Data\\Test\\Penguins.bmp") yIm = pengIm.convert("YCbCr") testIm = np.asarray(yIm) grey = testIm[:,:,0] grey = grey.astype('uint8') greyIm = im.fromarray(grey, "L") greyIm.save("Data\\Test\\grey.bmp") I'm expecting a greyscale version of my image, but what I get is this jumbled up mess: http://i.imgur.com/zlhIh.png Can anybody explain to me where I'm going wrong? The same code in matlab works exactly as I expect.

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  • TurnKey Linux

    <b>Linux Journal:</b> "Ever wanted to instantly have Drupal, Moodle, OTRS, MySQL, WordPress, Zimbra, Bugzilla, phpBB or a slew of other open source software packages up an running in a hassle-free manner to try out or available for rapid deployment? TurnKey Linux gives you just that."

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  • DTLoggedExec 1.0 Stable Released!

    - by Davide Mauri
    After serveral years of development I’ve finally released the first non-beta version of DTLoggedExec! I’m now very confident that the product is stable and solid and has all the feature that are important to have (at least for me). DTLoggedExec 1.0 http://dtloggedexec.codeplex.com/releases/view/44689 Here’s the release notes: FIRST NON-BETA RELEASE! :) Code cleaned up Added SetPackageInfo method to ILogProvider interface to make easier future improvements Deprecated the arguments 'ProfileDataFlow', 'ProfilePath', 'ProfileFileName' Added the new argument 'ProfileDataFlowFileName' that replaces the old 'ProfileDataFlow', 'ProfilePath', 'ProfileFileName' arguments Updated database scripts to support new reports Split releases in three different packages for easier maintenance and updates: DTLoggedExec Executable, Samples & Reports Fixed Issue #25738 (http://dtloggedexec.codeplex.com/WorkItem/View.aspx?WorkItemId=25738) Fixed Issue #26479 (http://dtloggedexec.codeplex.com/WorkItem/View.aspx?WorkItemId=26479) To make things easier to maintain I’ve divided the original package in three different releases. One is the DTLoggedExec executable; samples and reports are now available in separate packages so that I can update them more frequently without having to touch the engine. Source code of everything is available through Source Code Control: http://dtloggedexec.codeplex.com/SourceControl/list/changesets As usual, comments and feebacks are more than welcome! (Just use Codeplex, please, so it will be easier for me to keep track of requests and issues) Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Avoid closing Jquery's FancyBox

    - by user309745
    Hi I am using fanxybox 1.2.6 but it's getting closed despite of mentionig onContentClick:false Here is the code: $("#"+vari).fancybox({'hideOnContentClick':false }).trigger('click'); Kindly help me out p.s: The window is loading content from other URL(via Iframe)

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  • Visual Studio project remains "stuck" when stopped

    - by Traveling Tech Guy
    Hi, Currently developing a connector DLL to HP's Quality Center. I'm using their (insert expelative) COM API to connect to the server. An Interop wrapper gets created automatically by VStudio. My solution has 2 projects: the DLL and a tester application - essentially a form with buttons that call functions in the DLL. Everything works well - I can create defects, update them and delete them. When I close the main form, the application stops nicely. But when I call a function that returns a list of all available projects (to fill a combo box), if I close the main form, VStudio still shows the solution as running and I have to stop it. I've managed to pinpoint a single function in my code that when I call, the solution remains "hung" and if I don't, it closes well. It's a call to a property in the TDC object get_VisibleProjects that returns a List (not the .Net one, but a type in the COM library) - I just iterate over it and return a proper list (that I later use to fill the combo box): public List<string> GetAvailableProjects() { List<string> projects = new List<string>(); foreach (string project in this.tdc.get_VisibleProjects(qcDomain)) { projects.Add(project); } return projects; } My assumption is that something gets retained in memory. If I run the EXE outside of VStudio it closes - but who knows what gets left behind in memory? My question is - how do I get rid of whatever calling this property returns? Shouldn't the GC handle this? Do I need to delve into pointers? Things I've tried: getting the list into a variable and setting it to null at the end of the function Adding a destructor to the class and nulling the tdc object Stepping through the tester function application all the way out, whne the form closes and the Main function ends - it closes, but VStudio still shows I'm running. Thanks for your assistance!

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  • Reading and writing to files simultaneously?

    - by vipersnake005
    Moved the question here. Suppose, I want to store 1,000,000,000 integers and cannot use my memory. I would use a file(which can easily handle so much data ). How can I let it read and write and the same time. Using fstream file("file.txt', ios::out | ios::in ); doesn't create a file, in the first place. But supposing the file exists, I am unable to use to do reading and writing simultaneously. WHat I mean is this : Let the contents of the file be 111111 Then if I run : - #include <fstream> #include <iostream> using namespace std; int main() { fstream file("file.txt",ios:in|ios::out); char x; while( file>>x) { file<<'0'; } return 0; } Shouldn't the file's contents now be 101010 ? Read one character and then overwrite the next one with 0 ? Or incase the entire contents were read at once into some buffer, should there not be atleast one 0 in the file ? 1111110 ? But the contents remain unaltered. Please explain. Thank you.

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  • What is the correct way to create dynamic javascript in ASP.net MVC2?

    - by sabbour
    I'm creating a Google Maps partial view/user control in my project that is passed a strongly typed list of objects containing latitude and longitude values. Currently, this is the code I have for the partial: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<Project.Models.Entities.Location>>" %> <!-- Place for google to put the map --> <div id="report_map_canvas" style="width: 100%; height: 728px; margin-bottom: 2px;"> </div> <script type='text/javascript'> google.load("maps", "2"); $(document).ready(initializeMap); function initializeMap() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById('report_map_canvas')); map.setCenter(new GLatLng(51.5, -0.1167), 2); <% foreach (var item in Model) { %> map.addOverlay(new GMarker(new GLatLng('<%= Html.Encode(item.latitude)%>','<%= Html.Encode(item.longitude)%>'),{ title: '<%= Html.Encode(String.Format("{0:F}",item.speed)) %> km/h '})); <% } %> map.setUIToDefault(); } } </script> Is it right to dynamically create the javascript file this way by looping over the list and emitting javascript? Is there a better way to do it?

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  • How can I dynamically resize the jQuery Colorbox plugin?

    - by James Skidmore
    The AJAX content loaded in a Colorbox has some JavaScript included that resizes things within the content. Colorbox determines its sizing based on the sizes before all of the AJAX happens. How can I make the Colorbox resize after the content has been loaded? Here is a link where someone said that you can call colorbox() again after it's been loaded, but I can't figure out how to do that: http://groups.google.com/group/colorbox/browse_thread/thread/535d21c69e9006b0

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  • Timer does not stop in android

    - by RBADS
    I made an application in android and used timer like this.. try { CountDownTimer start1 = new CountDownTimer(20000, 1000) { public void onTick(long millisUntilFinished) { TextView timeShow = (TextView)findViewById(R.id.showTime); timeShow.setText(" "+" 00:" +millisUntilFinished / 1000); } But my problem is i don't know how to stop timer. Any idea? I already tried: quitApplication.setOnClickListener(new OnClickListener() { public void onClick(View v) { start1.cancel(); Intent i = new Intent(v.getContext(), startGame.class); startActivity(i); // TODO Auto-generated method stub } });

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  • VS2008 adding SQL Server Database (SQL Server 2008 Mgmt Studio) not working

    - by Kahn
    I'm trying to practice using the ASP.Net MVC at home, but I ran into an impossible problem. I cannot open a connection to SQL Server 2008, I get this error: "Connections to SQL Server files (*.mdf) require SQL Server Express 2005 to function properly. ..." I've googled around for numerous responses, none of them either working or addressing this issue. I'm running Vista 32bit, my SQL Server 2008 Mgmt Studio is also 32bit, I have SP1 installed both on VS2008 Professional, as well as the SQL Server. I changed the machine.config connectionStrings from ./SQLExpress to my SQL Server 2008 name. Now if I connect manually through web.config, in an asp:datasource or code-behind, everything works fine. But for some reason trying to add a DB Connection directly like this always gets the error. This is pretty fatal, since I can't rightly do much unless I can use LINQ to SQL with my MVC test project, and this is the only way I know how. Worked fine in school and work, but not at home. Installing SQL Server Express 2005, as some have suggested, is not an option. Obviously it HAS to work with SQL Server 2008. Thanks in advance.

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  • How do I create self-relationships in polymorphic inheritance in Elixir and Pylons?

    - by Turukawa
    I am new to programming and am following the example in the Pylons documentation on creating a Wiki. The database I want to link to the wiki was created with Elixir so I rewrote the Wiki database schema and have continued from there. In the wiki there is a requirement for a Navigation table which is inherited by Pages and Sections. A section can have many pages, while a page can only have one section. In addition, each sibling node can be chain-referenced to each other. So: Nav has "section" (OneToMany) and "before" (OneToOne - to reference preceeding node) Page has "section" (ManyToOne - many pages in one section) and inherits "before" Section inherits all from Nav The code I've written looks like this: class Nav(Entity): using_options(inheritance='multi') name = Field(Unicode(30), default=u'Untitled Node') path = Field(Unicode(255), default=u'') section = OneToMany('Page', inverse='section') after = OneToOne('Nav', inverse='before') before = OneToMany('Nav', inverse='after') class Page(Nav): using_options(inheritance='multi') content = Field(UnicodeText, nullable=False) posted = Field(DateTime, default=now()) title = Field(Unicode(255), default=u'Untitled Page') heading = Field(Unicode(255)) tags = ManyToMany('Tag') comments = OneToMany('Comment') section = ManyToOne('Nav', inverse='section') class Section(Nav): using_options(inheritance='multi') Errors received on this: sqlalchemy.exc.OperationalError: (OperationalError) table nav has no column named aftr_id u'INSERT INTO nav (name, path, aftr_id, row_type) VALUES (?, ?, ?, ?)' I've also tried: before = ManyToMany('Nav', inverse='before') on Nav in the hopes this might break the problem, but also not. The original SQLAlchemy code from the tutorial for these declarations is as follows: nav_table = schema.Table('nav', meta.metadata, schema.Column('id', types.Integer(), schema.Sequence('nav_id_seq', optional=True), primary_key=True), schema.Column('name', types.Unicode(255), default=u'Untitled Node'), schema.Column('path', types.Unicode(255), default=u''), schema.Column('section', types.Integer(), schema.ForeignKey('nav.id')), schema.Column('before', types.Integer(), default=None), schema.Column('type', types.String(30), nullable=False) ) page_table = schema.Table('page', meta.metadata, schema.Column('id', types.Integer, schema.ForeignKey('nav.id'), primary_key=True), schema.Column('content', types.Text(), nullable=False), schema.Column('posted', types.DateTime(), default=now), schema.Column('title', types.Unicode(255), default=u'Untitled Page'), schema.Column('heading', types.Unicode(255)), ) section_table = sa.Table('section', meta.metadata, schema.Column('id', types.Integer, schema.ForeignKey('nav.id'), primary_key=True), ) orm.mapper(Nav, nav_table, polymorphic_on=nav_table.c.type, polymorphic_identity='nav') orm.mapper(Section, section_table, inherits=Nav, polymorphic_identity='section') orm.mapper(Page, page_table, inherits=Nav, polymorphic_identity='page', properties={ 'comments':orm.relation(Comment, backref='page', cascade='all'), 'tags':orm.relation(Tag, secondary=pagetag_table) }) Any help is much appreciated.

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  • PGP - MailCloak/Gpg4Win/etc

    - by ericl42
    Hello, I have used Gpg4Win in the past along with FireGPG to have encryption on my emails. I am needing to roll this out to quite a few more people and was wondering if anyone else had some products they preferred better. The criteria I need is free and as user friendly as possible. I looked at MailCloak but I have had some issues with it on 1 of the 2 computers I've been testing on. It seems like it might work pretty well as a overall solution but on my computer I keep getting "Identity cannot be created." and not sure whats going on with that. Thanks for the info.

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  • Why my images are compressed?

    - by Johnny
    I'm using layout xml file for the UI. But the images are compressed and the qualities have lost in some level. My code is like this: <ImageView android:layout_width="480px" android:layout_height="717px" android:layout_x="0px" android:layout_y="45px" android:scaleType="fitXY" android:src="@drawable/e4" /> The drawable is actually 480x717. What's the problem here? Is it due to the fitXY?

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  • Wifi functionality

    - by rantravee
    Hello Does anyone knows if the wifi networks for android phones are based on Access Point Names (APN) ? I ask because in my android application I plan to overwrite some fields in all APN's to disable cellular network, but I still want to have available the wifi for the user

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  • Memory Regions displayed in SMAPS output with no permissions

    - by crissangel
    If I see the output of cat /proc//smaps, I find that there are some memory regions with which no read/write/execute permissions have been associated. Also these region are mapped to inode number 0. I wanted to know how does a region end up in such a state? Is it some sort of memory leak? Can these regions be ever used again by the process?

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  • creating new array according to input

    - by gcc
    int *arrays[20],j,a=0; /*int num_arrays;*/ char *tutar[200]; int /*fe*/i=0,n,temp; do{ tutar[i]=malloc(sizeof(int)); scanf("%s",tutar[i]); temp=*tutar[i]; ++i; } while(temp!='x'); int *arrays[20],j,a=0; n=i; j=1; for(i=1;i if(atoi(tutar[i])=='n') { ++j; arrays[j]=malloc(sizeof(int)); a=0; } arrays[j][a]=*(int *)tutar[i]; if(atoi(tutar[i])=='x') break; } input: 1 2 3 4 n 14 23 39 n 98 100 x output: arrays[1]:2 3 4 arrays[2]:14 23 39 arrays[3]:98 100 //i wanna output like that but my code didnt give me output like that //can anyone fix my code or (explain where is my error)

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