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  • Starting a career in quantitative finance

    - by Vitor Braga
    I've been reading John Hull book (Options, Futures and Other Derivatives) mostly on curiosity. I've read other books about financial markets in the past (like Elder's Trading for Living and the novel Reminiscences of a Stock Operator). But I'm really hooked by the John Hull book. My background is mostly scientific computing: number crunching, visualization and image processing. Mostly in C++, with some C, Fortran, Python, Ruby here and there. I've been thinking on moving on to quantitative finance - I'd like to do that. What would be the best way to start? Any tips?

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  • how to plot scatterplot and histogram using R [migrated]

    - by Wee Wang Wang
    I have a dataset about maximum wind speed(cm) as below: Year Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec 2011 4.5 5.6 5.0 5.4 5.0 5.0 5.2 5.3 4.8 5.4 5.4 3.8 2010 4.6 5.0 5.8 5.0 5.2 4.5 4.4 4.3 4.9 5.2 5.2 4.6 2009 4.5 5.3 4.3 3.9 4.7 5.0 4.8 4.7 4.9 5.6 4.9 4.1 2008 3.8 1.9 5.6 4.7 4.7 4.3 5.9 4.9 4.9 5.6 5.2 4.4 2007 4.6 4.6 4.6 5.6 4.2 3.6 2.5 2.5 2.5 3.3 5.6 1.5 2006 4.3 4.8 5.0 5.2 4.7 4.6 3.2 3.4 3.6 3.9 5.9 4.4 2005 2.7 4.3 5.7 4.7 4.6 5.0 5.6 5.0 4.9 5.9 5.6 1.8 How to create monthly max wind speed scatterplot (month in x-axis and wind speed in y-axis) and also the monthly max wind speed histogram by using R programming?

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  • How to choose an agile methodology?

    - by Christophe Debove
    I'm working in a little firm about 10 developpers, we are working a kind of agile way but knowledgeless and without formalism. I think be aware of what are agile method, what can they afford to us, may render more productive our products. However there is a lot of agile method, which could be the simplest to "learn"? Rapid Application Development Dynamic systems development method Scrum Feature Driven Development Extreme programming Adaptive software development Test Driven Development Crystal clear

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  • Is rotating the lead developer a good or bad idea?

    - by Renesis
    I work on a team that has been flat organizationally since it's creation several months ago. My manager is non-technical and this means that our whole team is responsible for decision-making. My manager is beginning to realize that there are several benefits to having a lead developer, both for his sake (a single point of contact and single responsible party for tasks) and ours (dispute resolution, organized technical guidance, etc.). Because the team has been flat, one concern is that picking one lead developer may discourage the others. A non-developer suggested to my manager that rotating the lead developer is a possible way to avoid this issue. One developer would be lead one month, another the next, and so on. Is this a good idea? Why or why not? Keep in mind that this means all developers — All developers are good, but not necessarily equally suited to leadership. And if it is not, suppose I am likely the best candidate for lead developer — how do I recommend that we avoid this approach without looking like it's merely for selfish reasons? (In other words, the team is small enough that anyone recommending a single leader is likely to appear to be recommending themselves — especially those who have been part of the team longer.)

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  • Does the type of prior employers matter when applying for a new job?

    - by Peter Smith
    Is there a bias in industry regarding the kind of previous employers an applicant has had (Government contractors, researchers, small business, large corporations)? I'm currently working for a University as a generalist programmer and I like my job here. But I'm worried that if I had to switch jobs down the road and apply for a corporate job that my resume would be dismissed based on the fact that I'm working in academia.

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  • How should an API use http basic authentication

    - by user1626384
    When an API requires that a client authenticates to it, i've seen two different scenarios used and I am wondering which case I should use for my situation. Example 1. An API is offered by a company to allow third parties to authenticate with a token and secret using HTTP Basic. Example 2. An API accepts a username and password via HTTP Basic to authenticate an end user. Generally they get a token back for future requests. My Setup: I will have an JSON API that I use as my backend for a mobile and web app. It seems like good practice for both the mobile and web app to send along a token and secret so only these two apps can access the API blocking any other third party. But the mobile and web app allow users to login and submit posts, view their data, etc. So I would want them to login via HTTP Basic as well on each request. Do I somehow use a combination of both these methods or only send the end user credentials (username and token) on each request? If I only send the end user credentials, do I store them in a cookie on the client?

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  • Handling changes to data types and entries in a database migration

    - by jandjorgensen
    I'm fully redesigning a site that indexes a number of articles with basic search functionality. The previous site was written about a decade ago, and I'm salvaging about 30,000 entries with data stored in less-than-ideal formats. While I'm moving from MSSQL to MySQL, I don't need to make any "live" changes, so this is not a production-level migration issue so much as a redesign. For instance, dates are stored the same as tags/subjects about the articles, but in strings as "YYYYMMDDd" (the lowercase d stands for "date" in the string). Essentially, before or after I move from the previous database format to a new one, I'm going to need to do a lot of replacement of individual entries. While I understand how to do operations with regular expressions in non-database issues, my database experience isn't robust enough to know the best way to handle this. What is the best (or standard) way to handle major changes like this? Is there an SQL operation I should be looking into? Please let me know if the problem isn't clear--I'm not entirely sure what kind of answer I'm looking for.

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  • Environment naming standards in software development?

    - by Marcus_33
    My project is currently suffering from environment naming issues. Different people have different assumptions as to what environments should be named or what the names designate, and it's causing confusion when discussing them. I've done a bit of research and I haven't found any standards out there. The terms include "Local", "Sand", "Dev", "Test", "User", "QA", "Staging" and "Prod" (plus a few more that different people have asked about) I'm not looking for just opinions, though if there's one out there that "everyone" has I'll take it - I'm trying to find definitions advanced by some sort of authority, even if it's unofficial. Here's the environments we currently use: Environment on the developer's PC Shared Environment where developers directly upload code to self-test Shared Environment where standards and functionality are tested by QA people Shared Environment where completed and QA-checked code is approved by project requesters Environment that mirrors the final environment as a final check and to prepare for deployment Final Environment where code is in use I know what I'd call them, but is there some sort of standard on this? Thanks in advance.

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  • Which would be a better way to load data via ajax

    - by Mike
    I am using google maps and returning html/lat/long from my MySQL database Currently A user picks a business category e.g; "Video Production". an ajax call is sent to a CodeIgniter controller the Controller then queries the db, and returns the following data via JSON Lat/Long of the marker HTML for the popup window this is approximately 34 rows in the database across two tables per business the ajax call receives this data and then plots the marker along with the html onto the map The data that is returned from the controller is one big json object... This is done for all businesses that exist in the Video Production category (currently approx 40 businesses). As you can see, pulling this data for multiple categories (100s of businesses) can get very very taxing on the server. My question is Would it be more beneficial to modify the process flow as such: a user picks a business category e.g; "Video Production". an ajax call is sent to a CodeIgniter controller the controller then queries the database for the location base information lat/long level (used to change marker icon color) This would be a single row per business with several columns the ajax call receives this data and then plots the marker on the map when the user clicks a marker an ajax call is sent to a CodeIgniter Controller the controller queries the database for the HTML and additional data based on business_id and if not, what are some better suggestions to this problem? In summary this means rather than including the HTML and additional data along for each business, only submitting minimal location information and then re-query for that information when each business marker is clicked. Potential Downsides longer load times when a user clicks a marker icon more code?? more queries to the database

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  • What are the tools required to build a compiler?

    - by kevin
    What are the various tools that are required to build a compiler for a particular programming language, say C? I want to know how each part of the compiler works. So, I am trying to use all the existing tools like loader, linker, etc, and combine them together to build one compiler (or can just say "compiling a compiler"). Can any one list out all such tools that are required to build a fully functional one?

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  • Finding the Twins when Implementing Catmull-Clark subdivision using Half-Edge mesh [migrated]

    - by Ailurus
    Note: The description became a little longer than expected. Do you know a readable implementation of this algorithm using this mesh? Please let me know! I'm trying to implement Catmull-Clark subdivision using Matlab (because later on the results have to be compared with some other stuff already implemented in Matlab). First try was with a Vertex-Face mesh, the algorithm works but it is of course not very efficient (since you need neighbouring information for edges and faces). Therefore, I'm now using a Half-Edge mesh (info), see also the paper of Lutz Kettner. Wikipedia link to the idea behind Catmull-Clark SDV: Wiki. My problem lies in finding the Twin HalfEdges, I'm just not sure how to do this. Below I'm describing my thoughts on the implementation, trying to keep it concise. Half-Edge mesh (using indices to Vertices/HalfEdges/Faces): Vertex (x,y,z,Outgoing_HalfEdge) HalfEdge (HeadVertex (or TailVertex, which one should I use), Next, Face, Twin). Face (HalfEdge) To keep it simple for now, assume that every face is a quadrilateral. The actual mesh is a list of Vertices, HalfEdges and Faces. The new mesh will consist of NewVertices, NewHalfEdges and NewFaces, like this (note: Number_... is the number of ...): NumberNewVertices: Number_Faces + Number_HalfEdges/2 + Number_Vertices NumberNewHalfEdges: 4 * 4 * NumberFaces NumberNewfaces: 4 * NumberFaces Catmull-Clark: Find the FacePoint (centroid) of each Face: --> Just average the x,y,z values of the vertices, save as a NewVertex. Find the EdgePoint of each HalfEdge: --> To prevent duplicates (each HalfEdge has a Twin which would result in the same HalfEdge) --> Only calculate EdgePoints of the HalfEdge which has the lowest index of the Pair. Update old Vertices Ok, now all the new Vertices are calculated (however, their Outgoing_HalfEdge is still unknown). Next step to save the new HalfEdges and Faces. This is the part causing me problems! Loop through each old Face, there are 4 new Faces to be created (because of the quadrilateral assumption) First create the 4 new HalfEdges per New Face, starting at the FacePoint to the Edgepoint Next a new HalfEdge from the EdgePoint to an Updated Vertex Another new one from the Updated Vertex to the next EdgePoint Finally the fourth new HalfEdge from the EdgePoint back to the FacePoint. The HeadVertex of each new HalfEdge is known, the Next HalfEdge too. The Face is also known (since it is the new face you're creating!). Only the Twin HalfEdge is unknown, how should I know this? By the way, while looping through the Vertices of the new Face, assign the Outgoing_HalfEdge to the Vertices. This is probably the place to find out which HalfEdge is the Twin. Finally, after the 4 new HalfEdges are created, save the Face with the HalfVertex index the last newly created HalfVertex. I hope this is clear, if needed I can post my (obviously not-yet-finished) Matlab code.

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  • Significance and role of Node.js in Web development

    - by Pankaj Upadhyay
    I have read that Node.js is a server-side javascript enviroment. This has put few thought and tinkers in my mind. Can we develop a complete data-drivent web application utilizing just JavaScript (along with node.js), HTML5 and CSS? Do we still need to use some server-side scripting language (e.g. C#, PHP)? In case we still need to use other scripting languages, what is node.js worth for, or useful? NOTE: Pardon with my knowledge about node.js.

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  • How to organize a programming course?

    - by Bogdan Gavril
    I've been given the task to train our manual testers to become developers in test (write test automation!). some have basic programing knowledge (either dabbling in PHP or reading stuff) and some who have no experience. Note that I do have teaching experience, but with real students, not employees, and one concern is that they will not put extra hours except the 20% management gave them for the transition. Language to be taught and used: C# We have 8 hours per week to do this and should decide if they will make it in 2 months. I am thinking of a combined approach: use a manual such as Head First C# (although I'm not happy with the labs, they're mostly games and I don't want to add UI complexities) have them read from the manual do labs with them, solving more and more difficult problems and explain the theoretical stuff as well have them do a bigger project towards the end Some questions: do you have a better suggestion as far as manuals go? do you have a better aproach? Focus less on labs? what kind of assesments should I use and how often? should I let them do a bigger project (bank system or small game) and how much time should I invest in that? ideeas on labs? other resources ? Any other tips would be most welcomed! Thanks!

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  • What FOSS solutions are available to manage software requirements?

    - by boos
    In the company where I work, we are starting to plan to be compliant to the software development life cycle. We already have, wiki, vcs system, bug tracking system, and a continuous integration system. The next step we want to have is to start to manage, in a structured way, software requirements. We dont want to use a wiki or shared documentation because we have many input (developer, manager, commercial, security analyst and other) and we dont want to handle proliferation of .doc around the network share. We are trying to search and we hope we can find and use a FOSS software to manage all this things. We have about 30 people, and don't have a budget for commercial software. We need a free solution for requirements management. What we want is software that can manage: Required features: Software requirements divided in a structured configurable way Versioning of the requirements (history, diff, etc, like source code) Interdependency of requirements (child of, parent of, related to) Rule Based Access Control for data handling Multi user, multi project File upload (for graph, document related to or so on) Report and extraction features Optional Features: Web Based Test case Time based management (timeline, excepted data, result data) Person allocation and so on Business related stuff Hardware allocation handling I have already play with testlink and now i'm playing with RTH, the next one i try is redmine.

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  • Why don't computers store decimal numbers as a second whole number?

    - by SomeKittens
    Computers have trouble storing fractional numbers where the denominator is something other than a solution to 2^x. This is because the first digit after the decimal is worth 1/2, the second 1/4 (or 1/(2^1) and 1/(2^2)) etc. Why deal with all sorts of rounding errors when the computer could have just stored the decimal part of the number as another whole number (which is therefore accurate?) The only thing I can think of is dealing with repeating decimals (in base 10), but there could have been an edge solution to that (like we currently have with infinity).

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  • Is there an established or defined best practice for source control branching between development and production builds?

    - by Matthew Patrick Cashatt
    Thanks for looking. I struggled in how to phrase my question, so let me give an example in hopes of making more clear what I am after: I currently work on a dev team responsible for maintaining and adding features to a web application. We have a development server and we use source control (TFS). Each day everyone checks in their code and when the code (running on the dev server) passes our QA/QC program, it goes to production. Recently, however, we had a bug in production which required an immediate production fix. The problem was that several of us developers had code checked in that was not ready for production so we had to either quickly complete and QA the code, or roll back everything, undo pending changes, etc. In other words, it was a mess. This made me wonder: Is there an established design pattern that prevents this type of scenario. It seems like there must be some "textbook" answer to this, but I am unsure what that would be. Perhaps a development branch of the code and a "release-ready" or production branch of the code?

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  • Books and stories on programming culture, specifically in the 80's / early 90's

    - by Ivo van der Wijk
    I've enjoyed a number of (fiction/non-fiction books) about hacker culture and running a software business in the 80's, 90's. For some reason things seemed so much more exciting back then. Examples are: Microserfs (Douglas Coupland) Accidental Empires (Robert X. Cringely Almost Pefect (W.E. Peterson, online!) Coders at Work (Peter Seibel) Today I'm an entrepeneur and programmer. Back in the 80's a I was a young geek hacking DOS TSR's and coding GWBasic / QBasic. In the 90's I was a C.S. university student, experiencing the rise of the Internet world wide. When reading these books running a software business seemed so much more fun than it is nowadays. Things used to be so much simpler, opportunities seemed to be everywhere and the startups seemed to work with much more real problems (inventing spreadsheets, writing word processors in assembly on 6 different platforms) than all our current web 2.0 social networking toys. Does anyone share these feelings? Does anyone have any good (personal) stories from back then or know of other good books to read?

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  • Resources for Learning CSS [closed]

    - by historicus
    I am a server-side programmer that is proficient in Java. I have fairly good knowledge of client-side scripting - primarily Javascript - but my ability in CSS is lacking. While I have the know-how to modify basic styles, I'd like to understand a bit more about CSS layouts and styling. Can anyone with expert knowledge of CSS provide a good source for diving into the topic? Also, are there any short, online courses that might help in gaining the information I seek?

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  • What simple game is good to learn OO principles?

    - by Bogdan Gavril
    I have to come up with a project propsal for my students, here are some details: The design should be gove over OO concepts: encapsulation, interfaces, inheritance, abstract classes Idealy a game, to keep interest high No GUI, just the console Effective time to finish this: ~ 6 days (1 person per proj) I have found one nice example of a game with carnivore and herbivore cells in a drop of water (array), it's a game of life twist. It is a bit too simple. Any ideeas? Aditional info: - language is C#

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  • Learning Python is good?

    - by user15220
    Recently I have seen some videos from MIT on computer programming topics. I found it's really worth watching. Especially the concepts of algorithms and fundamental stuffs. The programs were written and explained in Python. I never had looked into this language before as I learned and doing stuffs with C/C++ programming. But the cleanliness and better readability of syntax attracted me. Of course as a C++ programmer for long time it's the most readable language for me. Also I heard Python library contains solid algorithms and data-structures implementations. Can you share your experience in this language?

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  • Detect frameworks and/or CMS utilized on websites in Firefox

    - by jkneip
    I'm redesigning the website for my academic library and am examining other sites to determine to identify the technologies used. Things like: Web frameworks Javascript frameworks Server-side technology Content management system Now I've had some real success in Firefox using plugins like Wappalyzer, Firebug, and the DOM Inspector. But some sites just don't display any of the info. I'm looking for using these tools, especially it seems it an enterprise-level CMS is being used. Does anyone know of any other tools to detect this kind of data? Also with Firebug & the DOM Inspector, there is a lot of info. displayed and I wondered if there was a way to derive the presence of server-side technologies, CMS's, etc. within certain elements of a web page? Also, if this question is more relevant to another Stack Exchange site, please let me know and I'll post it there instead. Much thanks, Jason

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  • 8-Puzzle Solution executes infinitely [migrated]

    - by Ashwin
    I am looking for a solution to 8-puzzle problem using the A* Algorithm. I found this project on the internet. Please see the files - proj1 and EightPuzzle. The proj1 contains the entry point for the program(the main() function) and EightPuzzle describes a particular state of the puzzle. Each state is an object of the 8-puzzle. I feel that there is nothing wrong in the logic. But it loops forever for these two inputs that I have tried : {8,2,7,5,1,6,3,0,4} and {3,1,6,8,4,5,7,2,0}. Both of them are valid input states. What is wrong with the code? Note For better viewing copy the code in a Notepad++ or some other text editor(which has the capability to recognize java source file) because there are lot of comments in the code. Since A* requires a heuristic, they have provided the option of using manhattan distance and a heuristic that calculates the number of misplaced tiles. And to ensure that the best heuristic is executed first, they have implemented a PriorityQueue. The compareTo() function is implemented in the EightPuzzle class. The input to the program can be changed by changing the value of p1d in the main() function of proj1 class. The reason I am telling that there exists solution for the two my above inputs is because the applet here solves them. Please ensure that you select 8-puzzle from teh options in the applet. EDITI gave this input {0,5,7,6,8,1,2,4,3}. It took about 10 seconds and gave a result with 26 moves. But the applet gave a result with 24 moves in 0.0001 seconds with A*. For quick reference I have pasted the the two classes without the comments : EightPuzzle import java.util.*; public class EightPuzzle implements Comparable <Object> { int[] puzzle = new int[9]; int h_n= 0; int hueristic_type = 0; int g_n = 0; int f_n = 0; EightPuzzle parent = null; public EightPuzzle(int[] p, int h_type, int cost) { this.puzzle = p; this.hueristic_type = h_type; this.h_n = (h_type == 1) ? h1(p) : h2(p); this.g_n = cost; this.f_n = h_n + g_n; } public int getF_n() { return f_n; } public void setParent(EightPuzzle input) { this.parent = input; } public EightPuzzle getParent() { return this.parent; } public int inversions() { /* * Definition: For any other configuration besides the goal, * whenever a tile with a greater number on it precedes a * tile with a smaller number, the two tiles are said to be inverted */ int inversion = 0; for(int i = 0; i < this.puzzle.length; i++ ) { for(int j = 0; j < i; j++) { if(this.puzzle[i] != 0 && this.puzzle[j] != 0) { if(this.puzzle[i] < this.puzzle[j]) inversion++; } } } return inversion; } public int h1(int[] list) // h1 = the number of misplaced tiles { int gn = 0; for(int i = 0; i < list.length; i++) { if(list[i] != i && list[i] != 0) gn++; } return gn; } public LinkedList<EightPuzzle> getChildren() { LinkedList<EightPuzzle> children = new LinkedList<EightPuzzle>(); int loc = 0; int temparray[] = new int[this.puzzle.length]; EightPuzzle rightP, upP, downP, leftP; while(this.puzzle[loc] != 0) { loc++; } if(loc % 3 == 0){ temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); }else if(loc % 3 == 1){ //add one child swaps with right temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); //add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); }else if(loc % 3 == 2){ // add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); } if(loc / 3 == 0){ //add one child swaps with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if(loc / 3 == 1 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); //add one child, swap with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if (loc / 3 == 2 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); } return children; } public int h2(int[] list) // h2 = the sum of the distances of the tiles from their goal positions // for each item find its goal position // calculate how many positions it needs to move to get into that position { int gn = 0; int row = 0; int col = 0; for(int i = 0; i < list.length; i++) { if(list[i] != 0) { row = list[i] / 3; col = list[i] % 3; row = Math.abs(row - (i / 3)); col = Math.abs(col - (i % 3)); gn += row; gn += col; } } return gn; } public String toString() { String x = ""; for(int i = 0; i < this.puzzle.length; i++){ x += puzzle[i] + " "; if((i + 1) % 3 == 0) x += "\n"; } return x; } public int compareTo(Object input) { if (this.f_n < ((EightPuzzle) input).getF_n()) return -1; else if (this.f_n > ((EightPuzzle) input).getF_n()) return 1; return 0; } public boolean equals(EightPuzzle test){ if(this.f_n != test.getF_n()) return false; for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } public boolean mapEquals(EightPuzzle test){ for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } } proj1 import java.util.*; public class proj1 { /** * @param args */ public static void main(String[] args) { int[] p1d = {1, 4, 2, 3, 0, 5, 6, 7, 8}; int hueristic = 2; EightPuzzle start = new EightPuzzle(p1d, hueristic, 0); int[] win = { 0, 1, 2, 3, 4, 5, 6, 7, 8}; EightPuzzle goal = new EightPuzzle(win, hueristic, 0); astar(start, goal); } public static void astar(EightPuzzle start, EightPuzzle goal) { if(start.inversions() % 2 == 1) { System.out.println("Unsolvable"); return; } // function A*(start,goal) // closedset := the empty set // The set of nodes already evaluated. LinkedList<EightPuzzle> closedset = new LinkedList<EightPuzzle>(); // openset := set containing the initial node // The set of tentative nodes to be evaluated. priority queue PriorityQueue<EightPuzzle> openset = new PriorityQueue<EightPuzzle>(); openset.add(start); while(openset.size() > 0){ // x := the node in openset having the lowest f_score[] value EightPuzzle x = openset.peek(); // if x = goal if(x.mapEquals(goal)) { // return reconstruct_path(came_from, came_from[goal]) Stack<EightPuzzle> toDisplay = reconstruct(x); System.out.println("Printing solution... "); System.out.println(start.toString()); print(toDisplay); return; } // remove x from openset // add x to closedset closedset.add(openset.poll()); LinkedList <EightPuzzle> neighbor = x.getChildren(); // foreach y in neighbor_nodes(x) while(neighbor.size() > 0) { EightPuzzle y = neighbor.removeFirst(); // if y in closedset if(closedset.contains(y)){ // continue continue; } // tentative_g_score := g_score[x] + dist_between(x,y) // // if y not in openset if(!closedset.contains(y)){ // add y to openset openset.add(y); // } // } // } } public static void print(Stack<EightPuzzle> x) { while(!x.isEmpty()) { EightPuzzle temp = x.pop(); System.out.println(temp.toString()); } } public static Stack<EightPuzzle> reconstruct(EightPuzzle winner) { Stack<EightPuzzle> correctOutput = new Stack<EightPuzzle>(); while(winner.getParent() != null) { correctOutput.add(winner); winner = winner.getParent(); } return correctOutput; } }

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  • Can WinRT really be used at just the boundaries?

    - by Bret Kuhns
    Microsoft (chiefly, Herb Sutter) recommends when using WinRT with C++/CX to keep WinRT at the boundaries of the application and keep the core of the application written in standard ISO C++. I've been writing an application which I would like to leave portable, so my core functionality was written in standard C++, and I am now attempting to write a Metro-style front end for it using C++/CX. I've had a bit of a problem with this approach, however. For example, if I want to push a vector of user-defined C++ types to a XAML ListView control, I have to wrap my user-defined type in a WinRT ref/value type for it to be stored in a Vector^. With this approach, I'm inevitably left with wrapping a large portion of my C++ classes with WinRT classes. This is the first time I've tried to write a portable native application in C++. Is it really practical to keep WinRT along the boundaries like this? How else could this type of portable core with a platform-specific boundary be handled?

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  • Should maven generate jaxb java code or just use java code from source control?

    - by Peter Turner
    We're trying to plan how to mash together a build server for our shiny new java backend. We use a lot of jaxb XSD code generation and I was getting into a heated argument with whoever cared that the build server should delete jaxb created structures that were checked in generate the code from XSD's use code generated from those XSD's Everyone else thought that it made more sense to just use the code they checked in (we check in the code generated from the XSD because Eclipse pretty much forces you to do this as far as I can tell). My only stale argument is in my reading of the Joel test is that making the build in one step means generating from the source code and the source code is not the java source, but the XSD's because if you're messing around with the generated code you're gonna get pinched eventually. So, given that we all agree (you may not agree) we should probably be checking in our generate java files, should we use them to generate our code or should we generate it using the XSD's?

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  • How to teach computer science ?

    - by proferikson
    I am just starting to teach computer science. It's just the basic level. I'm finding that I sometimes don't know how to approach topics in a way that lets students easily understand. I've found that the best thing is to use analogies. A terrible one, that worked well, was presenting recursion by using the process of eating a burger. (You eat one bite, then you eat the rest). Interesting real world examples do wonders here. I'd like to know the techniques you have used for teaching, or teachers you've had have used that proved particularly effective. I'd also like to know your best analogies and examples for topics in CS101, especially for those harder to grasp topics. I'm teaching the class in Java (as required).

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