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  • Mono Develop 2.4.1 + linq error.

    - by Nev_Rahd
    I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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  • Prototyping Qt/C++ in Python

    - by tstenner
    I want to write a C++ application with Qt, but build a prototype first using Python and then gradually replace the Python code with C++. Is this the right approach, and what tools (bindings, binding generators, IDE) should I use? Ideally, everything should be available in the Ubuntu repositories so I wouldn't have to worry about incompatible or old versions and have everything set up with a simple aptitude install. Is there any comprehensive documentation about this process or do I have to learn every single component, and if yes, which ones? Right now I have multiple choices to make: Qt Creator, because of the nice auto completion and Qt integration. Eclipse, as it offers support for both C++ and Python. Eric (haven't used it yet) Vim PySide as it's working with CMake and Boost.Python, so theoretically it will make replacing python code easier. PyQt as it's more widely used (more support) and is available as a Debian package. Edit: As I will have to deploy the program to various computers, the C++-solution would require 1-5 files (the program and some library files if I'm linking it statically), using Python I'd have to build PyQt/PySide/SIP/whatever on every platform and explain how to install Python and everything else.

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  • How do you make use of the provider independency in the Entity Framework?

    - by Anders Svensson
    I'm trying to learn more about data access and the Entity Framework. My goal is to have a "provider independent" data access layer (to be able to switch easily e.g. from SQL Server to MySQL or vice versa), and since the EF is supposed to be provider independent it seems like a good way to go. But how do you use this provider independence? I mean, I was expecting to be able to sort of "program to an interface", and then just be able to switch database provider. But as far as I can tell I'm only getting a concrete type to program against, an "Entities" class, e.g. in my case it is: UserDBEntities _context = new UserDBEntities(); What I would have expected to be able to switch provider easily was to have an interface e.g. like IEntities _context = new UserDBEntities(); Sort of like I can do with datasets... But maybe that isn't how it works at all with EF? Or do you just switch provider in the connectionstring, and the model stays the same?? Please remember that I'm a complete newbie at this EF, and rather inexperienced with databases in general, so I would really appreciate if you could be as clear as possible :-)

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  • Strange Access Denied warning when running the simplest C++ program.

    - by DaveJohnston
    I am just starting to learn C++ (coming from a Java background) and I have come across something that I can't explain. I am working through the C++ Primer book and doing the exercises. Every time I get to a new exercise I create a new .cpp file and set it up with the main method (and any includes I think I will need) e.g.: #include <list> #include <vector> int main(int argc, char **args) { } and just to make sure I go to the command prompt and compile and run: g++ whatever.cpp a.exe Normally this works just fine and I start working on the exercise, but I just did it and got a strange error. It compiles fine, but when I run it it says Access Denied and AVG pops up telling me that a threat has been detected 'Trojan Horse Generic 17.CKZT'. I tried compiling again using the Microsoft Compiler (cl.exe) and it runs fines. So I went back, and added: #include <iostream> compiled using g++ and ran. This time it worked fine. So can anyone tell me why AVG would report an empty main method as a trojan horse but if the iostream header is included it doesn't?

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  • Timestamps and Intervals: NUMTOYMINTERVAL SYSTDATE CALCULATION SQL QUERY

    - by MeachamRob
    I am working on a homework problem, I'm close but need some help with a data conversion I think. Or sysdate - start_date calculation The question is: Using the EX schema, write a SELECT statement that retrieves the date_id and start_date from the Date_Sample table (format below), followed by a column named Years_and_Months_Since_Start that uses an interval function to retrieve the number of years and months that have elapsed between the start_date and the sysdate. (Your values will vary based on the date you do this lab.) Display only the records with start dates having the month and day equal to Feb 28 (of any year). DATE_ID START_DATE YEARS_AND_MONTHS_SINCE_START 2 Sunday , February 28, 1999 13-8 4 Monday , February 28, 2005 7-8 5 Tuesday , February 28, 2006 6-8 Our EX schema that refers to this question is simply a Date_Sample Table with two columns: DATE_ID NUMBER NOT Null START_DATE DATE I Have written this code: SELECT date_id, TO_CHAR(start_date, 'Day, MONTH DD, YYYY') AS start_date , NUMTOYMINTERVAL((SYSDATE - start_date), 'YEAR') AS years_and_months_since_start FROM date_sample WHERE TO_CHAR(start_date, 'MM/DD') = '02/28'; But my Years and months since start column is not working properly. It's getting very high numbers for years and months when the date calculated is from 1999-ish. ie, it should be 13-8 and I'm getting 5027-2 so I know it's not correct. I used NUMTOYMINTERVAL, which should be correct, but don't think the sysdate-start_date is working. Data Type for start_date is simply date. I tried ROUND but maybe need some help to get it right. Something is wrong with my calculation and trying to figure out how to get the correct interval there. Not sure if I have provided enough information to everyone but I will let you know if I figure it out before you do. It's a question from Murach's Oracle and SQL/PL book, chapter 17 if anyone else is trying to learn that chapter. Page 559.

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  • Port Java Application to Android

    - by mihirk
    I am not so sure about the question or what I should call what I am trying to achieve. I use a dialer called super sify. Here is the download - http://thegoan.com/supersify/supersify.zip The when extracted it has two files for linux, one is a .jar file which consists of some classes. The application was written in java. The other is a .sh file, which is a shell executable and takes some parameters like username and password and machine id and stuff. I want to port this app to android. What exactly would I have to do. Some more information is the .jar file is named supersify.jar and the .sh file is named ss.sh so here is the code for ss.sh java -jar supersify.jar $* if [ $? -eq 1 ] then read fi Please help me out. This is an open source software.So I am not doing any illegal modifications. I need to port this app to android, so would I have to write the whole thing again or just something else. I know some basic hello world android app development, and I have made an app to add two numbers, I am still on my way to become an android app developer, but I need this app and will learn a lot to make this possible unless it involves rewriting all the java classes. Thank you in advance If you have anymore question I will be glad to answer to them :D.

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  • Oddities in Linq-to-SQL generated code related to property change/changing events

    - by Lasse V. Karlsen
    I'm working on creating my own Linq-to-Sql generated classes in order to learn the concepts behind it all. I have some questions, if anyone knows the answer to one or more of these I'd be much obliged. The code below, and thus the questions, are from looking at code generated by creating a .DBML file in the Visual Studio 2010 designer, and inspecting the .Designer.cs file afterwards. 1. Why is INotifyPropertyChanging not passing the property name The event raising method is defined like this: protected virtual void SendPropertyChanging() Why isn't the name of the property that is changing passed to the event here? It is defined to be part of the EventArgs descendant that is passed to the event handler, but the method only passes an empty such value to it. 2. Why are the EntitySet<X> attach/detach methods not raising property changed? For an EntitySet<X> reference, the following two methods are generated: private void attach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = this; } private void detach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = null; } Why isn't SendPropertyChanged also called here? I'm sure I have more questions later, but for now these will suffice :)

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  • Best way to build an application based on R?

    - by Prasad Chalasani
    I'm looking for suggestions on how to go about building an application that uses R for analytics, table generation, and plotting. What I have in mind is an application that: displays various data tables in different tabs, somewhat like in Excel, and the columns should be sortable by clicking. takes user input parameters in some dialog windows. displays plots dynamically (i.e. user-input-dependent) either in a tab or in a new pop-up window/frame Note that I am not talking about a general-purpose fron-end/GUI for exploring data with R (like say Rattle), but a specific application. Some questions I'd like to see addressed are: Is an entirely R-based approach even possible ( on Windows ) ? The following passage from the Rattle article in R-Journal intrigues me: It is interesting to note that the first implementation of Rattle actually used Python for implementing the callbacks and R for the statistics, using rpy. The release of RGtk2 allowed the interface el- ements of Rattle to be written directly in R so that Rattle is a fully R-based application If it's better to use another language for the GUI part, which language is best suited for this? I'm looking for a language where it's relatively "painless" to build the GUI, and that also integrates very well with R. From this StackOverflow question How should I do rapid GUI development for R and Octave methods (possibly with Python)? I see that Python + PyQt4 + QtDesigner + RPy2 seems to be the best combo. Is that the consensus ? Anyone have pointers to specific (open source) applications of the type I describe, as examples that I can learn from?

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  • Twitter API similar to Google Alert

    - by Felix Perdana
    I am trying to create a web application which have a similar functionality with Google Alerts. (by similar I mean, the user can provide their email address for the alert to be sent to, daily or hourly) The only limitation is that it only gives alerts to user based on a certain keyword or hashtag. I think that I have found the fundamental API needed for this web application. https://dev.twitter.com/docs/api/1/get/search The problem is I still don't know all the web technologies needed for this application to work properly. For example, Do I have to store all of the searched keywords in database? Do I have to keep pooling ajax request all the time in order to keep my database updated? What if the keyword the user provided is very popular right now that might have thousands of tweets just in an hour (not to mention, there might be several emails that request several trending topics)? By the way, I am trying to build this application using PHP. So please let me know, what kind of techniques I need to learn for such web app (and some references maybe)? Any kind of help will be appreciated. Thanks in advance :) Regards, Felix Perdana

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  • accessing values in two dimensional arrays

    - by BrainLikeADullPencil
    In some code I'm trying to learn from, the Maze string below is turned into an array (code not shown for that) and saved in the instance variable @maze. The starting point of the Maze is represented by the letter 'A' in that Maze, which can be accessed at @maze[1][13]---row 1, column 13. However, the code I'm looking at uses @maze[1][13,1] to get the A, which you can see returns the same result in my console. If I do @maze[1][13,2], it returns the letter "A " with two blank spaces next to it, and so on. [13,3] returns "A " with three blank spaces. Does the 2 in [13,2] mean, "return two values starting at [1][13]? If so, why? Is this some feature of arrays or two dimensional arrays that I don't get? [20] pry(#<Maze>):1> @maze[1][13] => "A" [17] pry(#<Maze>):1> @maze[1][13,1] => "A" [18] pry(#<Maze>):1> @maze[1][13,2] => "A " [19] pry(#<Maze>):1> @maze[1][13,3] => "A " Maze String MAZE1 = %{##################################### # # # #A # # # # # # # # # ####### # ### # ####### # # # # # # # # # # # ##### # ################# # ####### # # # # # # # # # ##### ##### ### ### # ### # # # # # # # # # # # # B# # # # # # # # ##### ##### # # ### # # ####### # # # # # # # # # # # # # # ### ### # # # # ##### # # # ##### # # # # # # # # #####################################}

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  • OpenGL Pixel Format Attributes (NSOpenGLPixelFormatAttibutes) explanation?

    - by nacho4d
    Hi, I am not new to OpenGL, but not an expert. Many tutorials teach how to draw, 3D, 2D, projections, orthogonal, etc, but How about setting a the view? (NSOpenGLView in Cocoa, Macs). For example I have this: - (id) initWithFrame: (NSRect) frame { GLuint attribs[] = { //PF: PixelAttibutes NSOpenGLPFANoRecovery, NSOpenGLPFAWindow, NSOpenGLPFAAccelerated, NSOpenGLPFADoubleBuffer, NSOpenGLPFAColorSize, 24, NSOpenGLPFAAlphaSize, 8, NSOpenGLPFADepthSize, 24, NSOpenGLPFAStencilSize, 8, NSOpenGLPFAAccumSize, 0, 0 }; NSOpenGLPixelFormat* fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes: (NSOpenGLPixelFormatAttribute*) attribs]; return self = [super initWithFrame:frame pixelFormat: [fmt autorelease]]; } And I don't understand very well their usage, specially when combining them. For example: If I want my view to be capable of full screen should I write NSOpenGLPFAFullScreen only ? or both? (by capable I mean not always in full screen) Regarding Double Buffer, what is this exactly? (Below: Apple's definition) If present, this attribute indicates that only double-buffered pixel formats are considered. Otherwise, only single-buffered pixel formats are considered Regarding Color: if NSOpenGLPFAColorSize is 24 and NSOpenGLPFAColorSize is 8 then it means that alpha and RGB components are treated differently? what happen if I set the former to 32 and the later to 0? Etc, etc,In general how do I learn to set my view from scratch? Thanks in advance. Ignacio.

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  • Choosing right control for list of items

    - by prostynick
    I am new to WPF and MVVM. In my ViewModel I have collection of items, for example: class Item { string Title {get; set;} string Description {get; set;} } I would like to create a view, so at the beginning I would have: Title1 Title2 Title3 If user click on one of title it will expand to show description, eg: Title1 Description1 Title2 Title3 If user click on other title, there will be two expanded items: Title1 Description1 Title2 Description2 Title3 This is probably very similar to Expander control and maybe I could use it, but I am doing it other way, to learn something new. What control should I use for this purpose? Should that be ItemsControl or maybe ListBox? I imagine, that if I use ItemsControl, I should probably extend my Item class to have something like bool IsExpanded and bind UI item visibility to that value. But maybe I could use ListBox and somehow bind UI item visibility to... Yeah, to what? :) How could I do such a simple thing?

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  • Delphi: EInvalidOp in neural network class (TD-lambda)

    - by user89818
    I have the following draft for a neural network class. This neural network should learn with TD-lambda. It is started by calling the getRating() function. But unfortunately, there is an EInvalidOp (invalid floading point operation) error after about 1000 iterations in the following lines: neuronsHidden[j] := neuronsHidden[j]+neuronsInput[t][i]*weightsInput[i][j]; // input -> hidden weightsHidden[j][k] := weightsHidden[j][k]+LEARNING_RATE_HIDDEN*tdError[k]*eligibilityTraceOutput[j][k]; // adjust hidden->output weights according to TD-lambda Why is this error? I can't find the mistake in my code :( Can you help me? Thank you very much in advance! unit uNeuronalesNetz; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, StdCtrls, Grids, Menus, Math; const NEURONS_INPUT = 43; // number of neurons in the input layer NEURONS_HIDDEN = 60; // number of neurons in the hidden layer NEURONS_OUTPUT = 1; // number of neurons in the output layer NEURONS_TOTAL = NEURONS_INPUT+NEURONS_HIDDEN+NEURONS_OUTPUT; // total number of neurons in the network MAX_TIMESTEPS = 42; // maximum number of timesteps possible (after 42 moves: board is full) LEARNING_RATE_INPUT = 0.25; // in ideal case: decrease gradually in course of training LEARNING_RATE_HIDDEN = 0.15; // in ideal case: decrease gradually in course of training GAMMA = 0.9; LAMBDA = 0.7; // decay parameter for eligibility traces type TFeatureVector = Array[1..43] of SmallInt; // definition of the array type TFeatureVector TArtificialNeuralNetwork = class // definition of the class TArtificialNeuralNetwork private // GENERAL SETTINGS START learningMode: Boolean; // does the network learn and change its weights? // GENERAL SETTINGS END // NETWORK CONFIGURATION START neuronsInput: Array[1..MAX_TIMESTEPS] of Array[1..NEURONS_INPUT] of Extended; // array of all input neurons (their values) for every timestep neuronsHidden: Array[1..NEURONS_HIDDEN] of Extended; // array of all hidden neurons (their values) neuronsOutput: Array[1..NEURONS_OUTPUT] of Extended; // array of output neurons (their values) weightsInput: Array[1..NEURONS_INPUT] of Array[1..NEURONS_HIDDEN] of Extended; // array of weights: input->hidden weightsHidden: Array[1..NEURONS_HIDDEN] of Array[1..NEURONS_OUTPUT] of Extended; // array of weights: hidden->output // NETWORK CONFIGURATION END // LEARNING SETTINGS START outputBefore: Array[1..NEURONS_OUTPUT] of Extended; // the network's output value in the last timestep (the one before) eligibilityTraceHidden: Array[1..NEURONS_INPUT] of Array[1..NEURONS_HIDDEN] of Array[1..NEURONS_OUTPUT] of Extended; // array of eligibility traces: hidden layer eligibilityTraceOutput: Array[1..NEURONS_TOTAL] of Array[1..NEURONS_TOTAL] of Extended; // array of eligibility traces: output layer reward: Array[1..MAX_TIMESTEPS] of Array[1..NEURONS_OUTPUT] of Extended; // the reward value for all output neurons in every timestep tdError: Array[1..NEURONS_OUTPUT] of Extended; // the network's error value for every single output neuron t: Byte; // current timestep cyclesTrained: Integer; // number of cycles trained so far (learning rates could be decreased accordingly) last50errors: Array[1..50] of Extended; // LEARNING SETTINGS END public constructor Create; // create the network object and do the initialization procedure UpdateEligibilityTraces; // update the eligibility traces for the hidden and output layer procedure tdLearning; // learning algorithm: adjust the network's weights procedure ForwardPropagation; // propagate the input values through the network to the output layer function getRating(state: TFeatureVector; explorative: Boolean): Extended; // get the rating for a given state (feature vector) function HyperbolicTangent(x: Extended): Extended; // calculate the hyperbolic tangent [-1;1] procedure StartNewCycle; // start a new cycle with everything set to default except for the weights procedure setLearningMode(activated: Boolean=TRUE); // switch the learning mode on/off procedure setInputs(state: TFeatureVector); // transfer the given feature vector to the input layer (set input neurons' values) procedure setReward(currentReward: SmallInt); // set the reward for the current timestep (with learning then or without) procedure nextTimeStep; // increase timestep t function getCyclesTrained(): Integer; // get the number of cycles trained so far procedure Visualize(imgHidden: Pointer); // visualize the neural network's hidden layer end; implementation procedure TArtificialNeuralNetwork.UpdateEligibilityTraces; var i, j, k: Integer; begin // how worthy is a weight to be adjusted? for j := 1 to NEURONS_HIDDEN do begin for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceOutput[j][k] := LAMBDA*eligibilityTraceOutput[j][k]+(neuronsOutput[k]*(1-neuronsOutput[k]))*neuronsHidden[j]; for i := 1 to NEURONS_INPUT do begin eligibilityTraceHidden[i][j][k] := LAMBDA*eligibilityTraceHidden[i][j][k]+(neuronsOutput[k]*(1-neuronsOutput[k]))*weightsHidden[j][k]*neuronsHidden[j]*(1-neuronsHidden[j])*neuronsInput[t][i]; end; end; end; end; procedure TArtificialNeuralNetwork.setReward; VAR i: Integer; begin for i := 1 to NEURONS_OUTPUT do begin // +1 = player A wins // 0 = draw // -1 = player B wins reward[t][i] := currentReward; end; end; procedure TArtificialNeuralNetwork.tdLearning; var i, j, k: Integer; begin if learningMode then begin for k := 1 to NEURONS_OUTPUT do begin if reward[t][k] = 0 then begin tdError[k] := GAMMA*neuronsOutput[k]-outputBefore[k]; // network's error value when reward is 0 end else begin tdError[k] := reward[t][k]-outputBefore[k]; // network's error value in the final state (reward received) end; for j := 1 to NEURONS_HIDDEN do begin weightsHidden[j][k] := weightsHidden[j][k]+LEARNING_RATE_HIDDEN*tdError[k]*eligibilityTraceOutput[j][k]; // adjust hidden->output weights according to TD-lambda for i := 1 to NEURONS_INPUT do begin weightsInput[i][j] := weightsInput[i][j]+LEARNING_RATE_INPUT*tdError[k]*eligibilityTraceHidden[i][j][k]; // adjust input->hidden weights according to TD-lambda end; end; end; end; end; procedure TArtificialNeuralNetwork.ForwardPropagation; var i, j, k: Integer; begin for j := 1 to NEURONS_HIDDEN do begin neuronsHidden[j] := 0; for i := 1 to NEURONS_INPUT do begin neuronsHidden[j] := neuronsHidden[j]+neuronsInput[t][i]*weightsInput[i][j]; // input -> hidden end; neuronsHidden[j] := HyperbolicTangent(neuronsHidden[j]); // activation of hidden neuron j end; for k := 1 to NEURONS_OUTPUT do begin neuronsOutput[k] := 0; for j := 1 to NEURONS_HIDDEN do begin neuronsOutput[k] := neuronsOutput[k]+neuronsHidden[j]*weightsHidden[j][k]; // hidden -> output end; neuronsOutput[k] := HyperbolicTangent(neuronsOutput[k]); // activation of output neuron k end; end; procedure TArtificialNeuralNetwork.setLearningMode; begin learningMode := activated; end; constructor TArtificialNeuralNetwork.Create; var i, j, k: Integer; begin inherited Create; Randomize; // initialize random numbers generator learningMode := TRUE; cyclesTrained := -2; // only set to -2 because it will be increased twice in the beginning StartNewCycle; for j := 1 to NEURONS_HIDDEN do begin for k := 1 to NEURONS_OUTPUT do begin weightsHidden[j][k] := abs(Random-0.5); // initialize weights: 0 <= random < 0.5 end; for i := 1 to NEURONS_INPUT do begin weightsInput[i][j] := abs(Random-0.5); // initialize weights: 0 <= random < 0.5 end; end; for i := 1 to 50 do begin last50errors[i] := 0; end; end; procedure TArtificialNeuralNetwork.nextTimeStep; begin t := t+1; end; procedure TArtificialNeuralNetwork.StartNewCycle; var i, j, k, m: Integer; begin t := 1; // start in timestep 1 cyclesTrained := cyclesTrained+1; // increase the number of cycles trained so far for j := 1 to NEURONS_HIDDEN do begin neuronsHidden[j] := 0; for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceOutput[j][k] := 0; outputBefore[k] := 0; neuronsOutput[k] := 0; for m := 1 to MAX_TIMESTEPS do begin reward[m][k] := 0; end; end; for i := 1 to NEURONS_INPUT do begin for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceHidden[i][j][k] := 0; end; end; end; end; function TArtificialNeuralNetwork.getCyclesTrained; begin result := cyclesTrained; end; procedure TArtificialNeuralNetwork.setInputs; var k: Integer; begin for k := 1 to NEURONS_INPUT do begin neuronsInput[t][k] := state[k]; end; end; function TArtificialNeuralNetwork.getRating; begin setInputs(state); ForwardPropagation; result := neuronsOutput[1]; if not explorative then begin tdLearning; // adjust the weights according to TD-lambda ForwardPropagation; // calculate the network's output again outputBefore[1] := neuronsOutput[1]; // set outputBefore which will then be used in the next timestep UpdateEligibilityTraces; // update the eligibility traces for the next timestep nextTimeStep; // go to the next timestep end; end; function TArtificialNeuralNetwork.HyperbolicTangent; begin if x > 5500 then // prevent overflow result := 1 else result := (Exp(2*x)-1)/(Exp(2*x)+1); end; end.

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  • Chrome Extension - Console Log not firing

    - by coffeemonitor
    I'm starting to learn to make my own Chrome Extensions, and starting small. At the moment, I'm switching from using the alert() function to console.log() for a cleaner development environment. For some reason, console.log() is not displaying in my chrome console logs. However, the alert() function is working just fine. Can someone review my code below and perhaps tell me why console.log() isn't firing as expected? manifest.json { "manifest_version": 2, "name": "Sandbox", "version": "0.2", "description": "My Chrome Extension Playground", "icons": { "16": "imgs/16x16.png", "24": "imgs/24x24.png", "32": "imgs/32x32.png", "48": "imgs/48x48.png" }, "background": { "scripts": ["js/background.js"] }, "browser_action": { "default_title": "My Fun Sandbox Environment", "default_icon": "imgs/16x16.png" }, "permissions": [ "background", "storage", "tabs", "http://*/*", "https://*/*" ] } js/background.js function click(e) { alert("this alert certainly shows"); console.log("But this does not"); } // Fire a function, when icon is clicked chrome.browserAction.onClicked.addListener(click); As you can see, I kept it very simple. Just the manifest.json and a background.js file with an event listener, if the icon in the toolbar is clicked. As I mentioned, the alert() is popping up nicely, while the console.log() appears to be ignored.

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  • Web Applications Development: Security practices for Application design

    - by Shyam
    Hi, As I am creating more web applications that are targeted for multiple users, I figured out that I have to start thinking about user management and security. At a glance and in my ideal world, all users belong to a group. Permissions and access is thus defined per group (and inherited by the users of that group). Logically, I have my group of administrators, which are identified with a level "7" (integer) clearance. A group of webusers have for example level "1". This in generally all works great for me, but I need some kind of list that I have to keep in mind how I secure my system, and some general practices. I am not looking for a specific environment; I want to learn the why's and how's. An example is privilege escalation. If someone would be able to "push" themselves inside a group with higher privileges, for example the Administration, how can I prevent this, or what measures should I take to have some sort of precaution? I don't like in that case to walk into a caveat. My question is basically: where can I find a good resource, list, policy, book that explains the security of web applications, the why's, the how's and readable if you don't have any experience in the realm of advanced security? I prefer a free resource, as I believe I couldn't be the first one who thought about this. Thank you for your answers, comments and feedback.

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  • SQL problem - select accross multiple tables (user groups)

    - by morpheous
    I have a db schema which looks something like this: create table user (id int, name varchar(32)); create table group (id int, name varchar(32)); create table group_member (foobar_id int, user_id int, flag int); I want to write a query that allows me to so the following: Given a valid user id (UID), fetch the ids of all users that are in the same group as the specified user id (UID) AND have group_member.flag=3. Rather than just have the SQL. I want to learn how to think like a Db programmer. As a coder, SQL is my weakest link (since I am far more comfortable with imperative languages than declarative ones) - but I want to change that. Anyway here are the steps I have identified as necessary to break down the task. I would be grateful if some SQL guru can demonstrate the simple SQL statements - i.e. atomic SQL statements, one for each of the identified subtasks below, and then finally, how I can combine those statements to make the ONE statement that implements the required functionality. Here goes (assume specified user_id [UID] = 1): //Subtask #1. Fetch list of all groups of which I am a member Select group.id from user inner join group_member where user.id=group_member.user_id and user.id=1 //Subtask #2 Fetch a list of all members who are members of the groups I am a member of (i.e. groups in subtask #1) Not sure about this ... select user.id from user, group_member gm1, group_member gm2, ... [Stuck] //Subtask #3 Get list of users that satisfy criteria group_member.flag=3 Select user.id from user inner join group_member where user.id=group_member.user_id and user.id=1 and group_member.flag=3 Once I have the SQL for subtask2, I'd then like to see how the complete SQL statement is built from these subtasks (you dont have to use the SQL in the subtask, it just a way of explaining the steps involved - also, my SQL may be incorrect/inefficient, if so, please feel free to correct it, and point out what was wrong with it). Thanks

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  • What's best choice career-wise, to know a little about a lot or a lot about a little?

    - by nimo
    I work as a developer at a rather small company and we are providing a web application that is used by a big base of customers. Because we are so small everyone have to be able to do a lot of different tasks. It ranges from advanced support, developing the product (programming: c/c++, c#, php, sql, javascript, html, css), handle network configuration and network related issues and even sometimes go on sales meetings with potential customers. My concern is that I don't really specialize in any specific area. I know and learn little about a lot. I have graduated from school two years ago and this is my first real employment and when I look at other positions out there they always require so and so many years of experience in a specific area (for example 5 years of C#). For me to get that kind of specialized experience will be really hard at my current job. My question for you is what is, in your opinion, best choice career-wise, to know a little about a lot or a lot about a little? What path did you take? pros and cons that comes with that choice.

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  • C#: How to get all public (both get and set) string properties of a type

    - by Svish
    I am trying to make a method that will go through a list of generic objects and replace all their properties of type string which is either null or empty with a replacement. How is a good way to do this? I have this kind of... shell... so far: public static void ReplaceEmptyStrings<T>(List<T> list, string replacement) { var properties = typeof(T).GetProperties( -- What BindingFlags? -- ); foreach(var p in properties) { foreach(var item in list) { if(string.IsNullOrEmpty((string) p.GetValue(item, null))) p.SetValue(item, replacement, null); } } } So, how do I find all the properties of a type that are: Of type string Has public get Has public set ? I made this test class: class TestSubject { public string Public; private string Private; public string PublicPublic { get; set; } public string PublicPrivate { get; private set; } public string PrivatePublic { private get; set; } private string PrivatePrivate { get; set; } } The following does not work: var properties = typeof(TestSubject) .GetProperties(BindingFlags.Instance|BindingFlags.Public) .Where(ø => ø.CanRead && ø.CanWrite) .Where(ø => ø.PropertyType == typeof(string)); If I print out the Name of those properties I get there, I get: PublicPublic PublicPrivate PrivatePublic In other words, I get two properties too much. Note: This could probably be done in a better way... using nested foreach and reflection and all here... but if you have any great alternative ideas, please let me know cause I want to learn!

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  • How to check Internet status in iPhone

    - by Radix
    Hello; I wanted to check whether internet is connected or not using either the SystemConfiguration or the CFNetwork i am not quite sure which one. Then i want to know that if the internet is connected then is it connected through wifi or not. I tried an example where i used the below code -(IBAction) shownetworkStatus { NSURL *url = [NSURL URLWithString:@"www.google.com"]; if (url!=NULL) { lbl.text = @"Connected"; } else { lbl.text = @"notConnected"; } } some say that its not valid as per apple and you have to use the SystemConfiguration Framework, Please let me know what needs to be done. Also i personally think that what i am doing in the above code is not proper as if one day google may also be down due to maintenance or some other factors. Also if you could provide me a link where i could display the name of the WIFI network then it would be really cool. I searched the internet then i got these Reachability.h code which again is a bouncer as i wana learn the concepts not copy paste them Thanks and Regards Radix

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  • Java side scrolling game on android

    - by hanesjw
    I'm trying to make an easy side scrolling game just to learn the ropes of game programming on android. I came up with a solution of how to make it but I don't really think it is the most elegant solution. I wanted to get some different ideas on how to implement my game, as I really have no other solution right now. Here is a quick explanation of how it works.. I basically have blocks or objects fall from the top of the screen. The blocks are defined from a pre-defined string I create using a custom 'map-editor'. I create all the blocks at compile time, position them on or off the screen and simply increment their coordinates with each iteration of the gameloop. It is actually done a little bit better then that, but that gives a short easy explanation on the basic idea. I heard from a few people that instead of incrementing each block position, have the blocks stay there and simply change the viewable area. That makes sense, but I have no idea how to do it. Can anyone share some ideas or links on how I can implement something like this? I know my current solution isn't the greatest. Thanks!

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  • Which way to go in Linux 3D programming?

    - by Tek
    I'm looking for some answers for a project I'm thinking of. I've searched and from what I understand (correct me if I'm wrong) the only way the program I want to make will work is through 3D application. Let me explain. I plan to make a studio production program but it's unique in the fact that I want to be able to make it fluid. Let me explain. Imagine Microsoft's Surface program where you're able to touch and drag pictures across the screen. Instead of pictures I want them to be sound samples (wavs,mp3,etc). Of course instead the input will be with the mouse but if I ever do finish the project I would totally add touch screen input compatibility! Anyway, I'm guessing there's "physics" to do with it which is why I'm thinking that even though it'll be a 2D application I'll need to code it in a 3D environment. Assuming that I'm correct in how I want to approach my project, where can I start learning about 3D programming? I actually come from PHP programming which will make C++ easier for me to learn. But I don't even know where to start. If I'm not wrong OpenGL is the most up to date API as far as I know. Anyway, please give me your insights guys. I could really use some guidance here since I could totally be wrong in everything that I wrote :)

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  • Meaning of NEXT in Linked List creation in perl

    - by seleniumnewbie
    So I am trying to learn Linked Lists using Perl. I am reading "Mastering Algorithms with Perl" by Job Orwant. In the book he explains how to create a linked list I understand most of it, but I just simply fail to understand the command/index/key NEXT in the second last line of the code snippet. $list=undef; $tail=\$list; foreach (1..5){ my $node = [undef, $_ * $_]; $$tail = $node; $tail = \${$node->[NEXT]}; # The NEXT on this line? } What is he trying to do there? Isn $node a scalar, which stores the address of the unnamed array. Also even if we are de-referencing $node, should we not refer to the individual elements by an index number example (0,1). If we do use "NEXT" as a key, is $node a reference to a hash? I am very confused. Something in plain English will be highly appreciated.

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  • What's the best approach for getting into VS2010, C# 4, and WPF if my background is in C++/MFC

    - by Canacourse
    All my past programming experience has been in C++ on VS2003/8, Mostly service based and completely self taught. 2 Years ago I had to create my first real GUI app and (Foolishly) choose MFC. I got the app working but it took a long time & was a bit of a nightmare to learn MCF (and its many shortcomings) but I ended up with a reliable workable app which was difficult to change or extend. Again I have to create another GUI app more complex than the first and again this will be created from scratch and will only ever be used on windows. I had put off learning C# for a long time but not wishing to re-visit MFC have decided that the new application with be birthed in VS2010 and WPF 4 will be the midwife. Trying to avoid the several expensive (Time wise) mistakes I made previously. Im looking for for good books/tutorials on the current versions of C# 4 & WPF 4 and also general advice on the best approach. The application will do several things one of them would persisting info in a SQL DB. So Im thinking LINQ for that? Please chip in...

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  • C# and Excel best practices

    - by rlp
    I am doing a lot of MS Excel interop i C# (Visual Studio 2012) using Microsoft.Office.Interop.Excel. It requires a lot of tiresome manual code to include Excel formulas, doing formatting of text and numbers, and making graphs. I would like it very much if any of you have some input on how I do the task better. I have been looking at Visual Studio Tools for Office, but I am uncertain on its functions. I get it is required to make Excel add-ins, but does it help doing Excel automation? I have desperately been trying to find information on working with Excel in Visual Studio 2012 using C#. I did found some good but short tutorials. However I really would like a book an the subject to learn the field more in depth regarding functionality and best practices. Searching Amazon with my limited knowlegde only gives me book on VSTO using older versions of Visual Studio. I would not like to use VBA. My applications use Excel mainly for visualizing compiled from different sources. I also to data processing where Excel is not required. Futhermore, I can write C# but not VB.

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  • How do I vertcally align thumbnails of unknown height using jQuery?

    - by playahabana
    Ok, I am a complete beginner to this, in fact I am still building my first website. I am attempting to do this all by hand-coding without a CMS in order to try and learn as much possible as quickly as possible. If this post is in the wrong place I apologise, and a pointer to right place would be appreciated. Here goes, I am trying to peice together a bit of jQuery that will automatically vertically align my thumbnails in my image gallery (they are all different sizes). They are within fixed size div's and the function I am attempting looks something like this: <script type="text/javascript"> $('#ul.photo).bind(function() { var smartVert=$(this); var phty=ob.("ul.photo img").height(); //get height of photos var phtdif=Math.floor(208 - phty); //subtract height of photo from div height var phttop=Math.floor(phtdif / 2); //gets padding reqd. $ob.("ul.photo").css({'padding-top' : phttop}) //sets padding to center thumbnail }); smartVert(); unsurprisingly this doesn't work, if some kindly soul could take pity on a total noob, and point out where I am going wrong (probably in writing complete gibberish would be my first guess) it would be greatly appreciated- even if you could just point me in the direcion of a tutorial regarding these things, I have looked and found one reference that said such a function was easy to create, but it did not elaborate. thankyou in advance

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