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• SQL Server Database In Single User Mode after Failover

  - by jlichauc

  Here is a weird situation we experienced with a SQL Server 2008 Database Mirroring Failover. We have a pair of mirrored databases running in high-availability mode and both the principal and mirror showed as synchronized. As part of some maintenance I triggered a manual failover of the principal to the mirror. However after the failover the principal was now in single-user mode instead of the expected "Principal/Synchronized" state we usually get. The database had been in multi-user mode on the previous principal before this had happened. We ended up stopping all applications, restarting the SQL Server instances, and executing "ALTER DATABASE ... SET MULTI_USER" to bring the database back to the expected "Principal/Synchronized" state in a multi-user mode. Question. Does anyone know where SQL Server stores information about whether a database should be in single-user mode or not? I'm wondering if there is some system database or table that has this setting recorded somewhere. In particular we had an incident once with the database on the original principal (the one I was failing over to) where when trying to detach the database it was put into single-user mode. I'm wondering if that setting is cached somewhere and is the reason that SQL Server put it back into single-user mode after a failover.

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• Ajax heavy JS apps using excessive amounts of memory over time.

  - by Shane Reustle

  I seem to have some pretty large memory leaks in an app that I am working on. The app itself is not very complex. Every 15 seconds, the page requests approx 40kb of JSON from the server, and draws a table on the page using it. It is cheaper to draw the table over because the data is usually always new. I am attaching a few events to the table, approx 5 per line, 30 lines in the table. I used jQuery's .html() method to put the new html into the container and overwrite the existing. I do this specifically so that jQuery's special cleanup functions go in and attempt to detach all events on the elements in the element that it is overwriting. I then also delete the large variables of html once they are sent to the DOM using delete my_var. I have checked for circular references and attached events that are never cleared a few times, but never REALLY dug into it. I was wondering if someone could give me a few pointers on how to optimize a very heavy app like this. I just picked up "High Performance Javascript" by Nicholas Zakas, but didn't have much time to get into it yet. To give an idea on how much memory this is using, after 4~ hours, it is using about 420,000k on chrome, and much more on Firefox or IE. Thanks!

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• How to reuse results with a schema for end of day stock-data

  - by Vishalrix

  I am creating a database schema to be used for technical analysis like top-volume gainers, top-price gainers etc.I have checked answers to questions here, like the design question. Having taken the hint from boe100 's answer there I have a schema modeled pretty much on it, thusly: Symbol - char 6 //primary Date - date //primary Open - decimal 18, 4 High - decimal 18, 4 Low - decimal 18, 4 Close - decimal 18, 4 Volume - int Right now this table containing End Of Day( EOD) data will be about 3 million rows for 3 years. Later when I get/need more data it could be 20 million rows. The front end will be asking requests like "give me the top price gainers on date X over Y days". That request is one of the simpler ones, and as such is not too costly, time wise, I assume. But a request like " give me top volume gainers for the last 10 days, with the previous 100 days acting as baseline", could prove 10-100 times costlier. The result of such a request would be a float which signifies how many times the volume as grown etc. One option I have is adding a column for each such result. And if the user asks for volume gain in 10 days over 20 days, that would require another table. The total such tables could easily cross 100, specially if I start using other results as tables, like MACD-10, MACD-100. each of which will require its own column. Is this a feasible solution? Another option being that I keep the result in cached html files and present them to the user. I dont have much experience in web-development, so to me it looks messy; but I could be wrong ( ofc!) . Is that a option too? Let me add that I am/will be using mod_perl to present the response to the user. With much of the work on mysql database being done using perl. I would like to have a response time of 1-2 seconds.

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• Sharing storage between servers

  - by El Yobo

  I have a PHP based web application which is currently only using one webserver but will shortly be scaling up to another. In most regards this is pretty straightforward, but the application also stores a lot of files on the filesystem. It seems that there are many approaches to sharing the files between the two servers, from the very simple to the reasonably complex. These are the options that I'm aware of Simple network storage NFS SMB/CIFS Clustered filesystems Lustre GFS/GFS2 GlusterFS Hadoop DFS MogileFS What I want is for a file uploaded via one webserver be immediately available if accessed through the other. The data is extremely important and absolutely cannot be lost, so whatever is implemented needs to a) never lose data and b) have very high availability (as good as, or better, than a local filesystem). It seems like the clustered filesystems will also provide faster data access than local storage (for large files) but that isn't of vita importance at the moment. What would you recommend? Do you have any suggestions to add or anything specifically to look out for with the above options? Any suggestions on how to manage backup of data on the clustered filesystems?

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• VB.NET switching from ADO.NET to LINQ

  - by Cj Anderson

  I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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• How does mercurial's bisect work when the range includes branching?

  - by Joshua Goldberg

  If the bisect range includes multiple branches, how does hg bisect's search work. Does it effectively bisect each sub-branch (I would think that would be inefficient)? For instance, borrowing, with gratitude, a diagram from an answer to this related question, what if the bisect got to changeset 7 on the "good" right-side branch first. @ 12:8ae1fff407c8:bad6 | o 11:27edd4ba0a78:bad5 | o 10:312ba3d6eb29:bad4 |\ | o 9:68ae20ea0c02:good33 | | | o 8:916e977fa594:good32 | | | o 7:b9d00094223f:good31 | | o | 6:a7cab1800465:bad3 | | o | 5:a84e45045a29:bad2 | | o | 4:d0a381a67072:bad1 | | o | 3:54349a6276cc:good4 |/ o 2:4588e394e325:good3 | o 1:de79725cb39a:good2 | o 0:2641cc78ce7a:good1 Will it then look only between 7 and 12, missing the real first-bad that we care about? (thus using "dumb" numerical order) or is it smart enough to use the full topography and to know that the first bad could be below 7 on the right-side branch, or could still be anywhere on the left-side branch. The purpose of my question is both (a) just to understand the algorithm better, and (b) to understand whether I can liberally extend my initial bisect range without thinking hard about what branch I go to. I've been in high-branching bisect situations where it kept asking me after every test to extend beyond the next merge, so that the whole procedure was essentially O(n). I'm wondering if I can just throw the first "good" marker way back past some nest of merges without thinking about it much, and whether that would save time and give correct results.

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• Segmentation fault with queue in C

  - by Trevor

  I am getting a segmentation fault with the following code after adding structs to my queue. The segmentation fault occurs when the MAX_QUEUE is set high but when I set it low (100 or 200), the error doesn't occur. It has been a while since I last programmed in C, so any help is appreciated. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_QUEUE 1000 struct myInfo { char data[20]; }; struct myInfo* queue; void push(struct myInfo); int queue_head = 0; int queue_size = 0; int main(int argc, char *argv[]) { queue = (struct myInfo*) malloc(sizeof(struct myInfo) * MAX_QUEUE); struct myInfo info; char buf[10]; strcpy(buf, "hello"); while (1) { strcpy(info.data, buf); push(info); } } void push(struct myInfo info) { int next_index = sizeof(struct myInfo) * ((queue_size + queue_head) % MAX_QUEUE); printf("Pushing %s to %d\n", info.data, next_index); *(queue + (next_index)) = info; queue_size++; } Output: Pushing hello to 0 Pushing hello to 20 ... Pushing hello to 7540 Pushing hello to 7560 Pushing hello to 7580 Segmentation fault

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• What are some good ways to store performance statistics in a database for querying later?

  - by Nathan

  Goal: Store arbitrary performance statistics of stuff that you care about (how many customers are currently logged on, how many widgets are being processed, etc.) in a database so that you can understand what how your servers are doing over time. Assumptions: A database is already available, and you already know how to gather the information you want and are capable of putting it in the database however you like. Some Ideal Attributes of a Solution Causes no noticeable performance hit on the server being monitored Has a very high precision of measurement Does not store useless or redundant information Is easy to query (lends itself to gathering/displaying useful information) Lends itself to being graphed easily Is accurate Is elegant Primary Questions 1) What is a good design/method/scheme for triggering the storing of statistics? 2) What is a good database design for how to actually store the data? Example answers...that are sort of vague and lame... 1) I could, once per [fixed time interval], store a row of data with all the performance measurements I care about in each column of one big flat table indexed by timestamp and/or server. 2) I could have a daemon monitoring performance stuff I care about, and add a row whenever something changes (instead of at fixed time intervals) to a flat table as in #1. 3) I could trigger either as in #2, but I could store information about each aspect of performance that I'm measuring in separate tables, opening up the possibility of adding tons of rows for often-changing items, and few rows for seldom-changing items. Etc. In the end, I will implement something, even if it's some super-braindead approach I make up myself, but I'm betting there are some really smart people out there willing to share their experiences and bright ideas!

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• Redirect uploaded files to another server, using nginx

  - by Serg ikS

  I am creating a web service of scheduled posts to some soc. network.Need help dealing with file uploads under high traffic. Process overview: User uploads files to SomeServer (not mine). SomeServer then responds with a JSON string. My web app should store that JSON response. Opt. 1 — Save, cURL POST, delete tmp The stupid way I made it work: User uploads files to MyWebApp; MyWebApp cURL's the file further to SomeServer, getting the response. Opt.2 — JS magic The smart way it could be perfect: User uploads the file directly to SomeServer, from within an iFrame; MyWebApp gets the response through JavaScript. But this is(?) impossible due to the 'Same Origin Policy', isn't it? Opt. 3 — nginx proxying? The better way for a production server: User uploads files to MyWebApp; nginx intercepts the file uploads and sends them directly to the SomeServer; JSON response is also intercepted by nginx and processed by MyWebApp. Does this make any sense, and what would be the nginx config for, say, /fileupload Location to proxy it to SomeServer ?

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• lots of backbone views - performance issues?

  - by ksol

  tl;dr: I wonder if having lots (100+ for the moment, potentially up to 1000/2000 or more) of backbone views (as a cell of a table) is too heavy or not The project I'm working on revolves around a planning view. There one row per user that covers 6 hours of a day, each hour splitted in 4 slots of 15mn. This planning is used to add "reservations" when clicking on a slot, and should handle hovering of the correct slots, and also handle when it is NOT possible to make a reservation - ie. prevent user click on an "unavailable" slot. There is many reasons why a slot can't be clicked on: the user is not available at this time, or the user is in a reservation; or the app needs to "force" a delay slot between two reservations. Reservations (a div) are rendered in a slot (a cell of a table), and by toying with dimensions, hovers the right number of slots. All this screen is handled with backbone. So For each slot I'm hovering on, I need to check wether I can do a reservation here or not. As of this moment, I use this by toying with the data attributes on the slots : when a reservation object is added, the slots covered are "enhanced with (among others) the reservation object (the backbone view object). But in some cases I don't quite have a grasp on now, it mixes up, and when the reservation view is removed, the slots are not "cleaned up" : the previous class is not reset correctly. It is probably something I've done wrong or badly, but this is only going to get heavier; I think I should use another class of Backbone views here, but I'm afraid the number of slots and thereof of views objects will be high and cause performance issue. I don't know mush about js perf so I'd like to have some feedback before jumping on that train. Any other advice on how to do this would be quite welcomed too. Thanks for your time. If this is not clear enough, tell me, I'll try and rephrase it.

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• Download Current WSJ.com Prime Rate

  - by Registered User

  I need to automatically download the current Wall Street Journal Prime Rate and load the data into my database. What is the best method for downloading this data automatically? I have come up with three possible solutions for doing this: Scrape a HTML web page from WSJ. Parse a RSS news feed from WSJ. Use some API that I haven't found from WSJ. Regarding solution 1, although I don't like solution 1 since it could easily break, it's the only one that I have worked out from end to end. It appears I can scrape this page with a WebRequest / WebResponse and read the text in this code: <tr> <td style="text-align:left" class="colhead">&nbsp;</td> <td class="colhead">Latest</td> <td class="colhead">Wk ago</td> <td class="colhead">High</td> <td class="colhead">Low</td> </tr> <tr> <td class="text">U.S.</td> <td style="font-weight:bold;" class="num">3.25</td> <td class="num">3.25</td> <td class="num">3.25</td> <td class="num" style="border-right:0px">3.25</td> </tr> Regarding solution 2, although I can implement a RSS reader solution, I don't see a way to reliably anticipate verbiage for changes in the Prime Rate. Therefore, I don't think this is as safe or reliable a way to get the data as solution 1. Regarding solution 3, I haven't found any published API's for checking money rates like the Prime Rate. If anyone knows of a web service or other API for checking money rates, then please let me know.

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• How do the size standard libraries compare for different languages

  - by Roman A. Taycher

  Someone was recently raving about how great jQuery was and how it made javascript into a pleasure and also how the whole source code was so small(and one file). I looked it up on www.ohloh.net/ and it said it was about 30,000 lines of javascript, when I tired curl piped to wc it said about 5000 lines(strange discrepancy that, maybe test suites, ect?). I thought well it isn't that strange since javascript from what I've heard has a lot of fun dynamic tricks, so you can probably get away with a small library. But then I thought what about other high level languages, the ones with large standard libraries and wondered how big the standard are for python/ruby/haskell/pharo(smalltalk)/*ml/ect. (libraries not vm stuff to the degree its possible to separate it) Anybody know? Any details (comment/blank/code lines , test code lines, lines in language vs lines in ffi/byte-code) are appreciated! edit: ps. since it started this me asking about jQuery as a bonus if you could please list the size of mega frameworks, a megaframewok provides so much that people using an x megaframework in language y might sometimes refer to programming in xy or even x rather then in y (ie. : qt, jQuery, etc.).

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• (x86) Assembler Optimization

  - by Pindatjuh

  I'm building a compiler/assembler/linker in Java for the x86-32 (IA32) processor targeting Windows. High-level concepts of a "language" (in essential a Java API for creating executables) are translated into opcodes, which then are wrapped and outputted to a file. The translation process has several phases, one is the translation between languages: the highest-level code is translated into the medium-level code which is then translated into the lowest-level code (probably more than 3 levels). My problem is the following; if I have higher-level code (X and Y) translated to lower-level code (x, y, U and V), then an example of such a translation is, in pseudo-code: x + U(f) // generated by X + V(f) + y // generated by Y (An easy example) where V is the opposite of U (compare with a stack push as U and a pop as V). This needs to be 'optimized' into: x + y (essentially removing the "useless" code) My idea was to use regular expressions. For the above case, it'll be a regular expression looking like this: x:(U(x)+V(x)):null, meaning for all x find U(x) followed by V(x) and replace by null. Imagine more complex regular expressions, for more complex optimizations. This should work on all levels. What do you suggest? What would be a good approach to optimize in these situations?

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• Colorizing as SAS Map

  - by user601828

  I'm trying to generate a map in SAS where I would like to to make gradual color changes which correspond to my results. So the higher the counts the more intense the color changes. Also I would like to add state labels to the map. Here is my code, so far it produces a white map with varying degress of blue blocks. I'd like the states colored in intense colors, like red, bright pink,brilliant, blues and greens. Can anyone please help me modify the code to add state labels and colorize the map, and below the map add a table summarizing the statistics, like counts and percentages. Thanks in advance. goptions gunit=pct cback=white htitle=4 htext=3 colors=(PAGY LIY STY DEGY dark_yellow very_dark_yellow ) ; title "My Map Results"; proc gmap map=maps.us data=My_data all; id state; block person_per_event/levels=6; choro person_per_event/levels=6; run; quit; I looked at his page before for example if I wanted to make a map like this one http://robslink.com/SAS/democd61/election_2012.htm with my data. I tried modifying the code that he gives on the link, but wasnt very successful. I would like to use that map along with the state labels and keep the colors and represent my data with blocks in the corresponding locations with city and state, and high level counts. The rest of the summary statistics I would like to summarize in a colorful table next to the map, like a dashboard of sorts. Appreciate any help in advance. Thanks, -rachel

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• Delphi Performance: Case Versus If

  - by Andreas Rejbrand

  I guess there might be some overlapping with previous SO questions, but I could not find a Delphi-specific question on this topic. Suppose that you want to check if an unsigned 32-bit integer variable "MyAction" is equal to any of the constants ACTION1, ACTION2, ... ACTIONn, where n is - say 1000. I guess that, besides being more elegant, case MyAction of ACTION1: {code}; ACTION2: {code}; ... ACTIONn: {code}; end; if much faster than if MyAction = ACTION1 then // code else if MyAction = ACTION2 then // code ... else if MyAction = ACTIONn then // code; I guess that the if variant takes time O(n) to complete (i.e. to find the right action) if the right action ACTIONi has a high value of i, whereas the case variant takes a lot less time (O(1)?). Am I correct that switch is much faster? Am I correct that the time required to find the right action in the switch case actually is independent of n? I.e. is it true that it does not really take any longer to check a million cases than to check 10 cases? How, exactly, does this work?

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• Creating Mobile Cross-Platform Scripting Solution

  - by Aplomb

  I am having the dream to design a Mobile cross-platform scripting solution to achieve Developer only need to code once by scripting language(it's possible be Javascript or others need further investigation), then the solution will be able to generate the installation files for multiple mobile platforms like J2me, Android, Symbian, BlackBerry, Palm, Windows Mobile/Phone, iPhone, etc. Using the scripting language, developer can code with unified platform API. And other extension frameworks under scripting language, like, 1. 2D UI framework Most probably using for Mobile Applications, the UI style will compete with native UI framework and no longer every application in particular platform looks similar. 2. 3D UI framework Provide the platforms who has 3D capability can represent their Mobile Application with more fashion 3D style which will be much more abstractive. 3. Variable game engine Developers can can use it for easily and high-quality build games. 4. etc This Mobile solution is providing three points, 1. Cross-Platform 2. Scripting 3. Middleware So guys, what do you think about this idea, is it good for Developers? is it profitable? where is the better direction for this idea?

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• Discussion on SEO best-practices for site development involving php...

  - by Bradley Herman

  Recently in our work, I've started getting some experience with SEO (finally). It's something I've put off for a long time because I've always maintained that SEO is a buzz-word b.s. pseudo-science and more about providing quality, relevant content (assuming proper header tags and the basics are covered). However, sometimes a client doesn't have stellar content yet still demands SEO and high rankings. While it's not how I design sites 100% of the time (as design dictates structure), I typically create a basic template from the design my boss gives me, then I optimize it, and then strip the top and bottom and move those to header.php and footer.php, using the following to bring in the header and footer based on AJAX versus HTML requests: <?php if($_SERVER['HTTP_X_REQUESTED_WITH']==''){ include('includes/header.php'); }?> #content here <?php if($_SERVER['HTTP_X_REQUESTED_WITH']==''){ include('includes/footer.php'); }?> Then, I use jQuery to intercept page requests and I use AJAX to fill in, for example, a #copy div with the new content. This avoids unnecessarily loading all the header and footer info everytime, but still allows users without Java to access pages without any problems. (also to think about, depending on size of content, do the extra http requests added using this method render it more of a server strain versus a single, larger file?) I don't have a really solid understanding of the meta keywords and their SEO significance, but as I recall reading, the keywords, title, and description on a page should match up to the pages content--ie. each page should have slightly different keywords/description while retaining some common ground. What I'm getting at here is trying to foster a discussion on whether my approach is flawed to begin with, if there are things I can do (within reason) that keep the site structure simple but allow for better SEO practices, or if my SEO understandings are wrong. This isn't a question, per say, but hopefully a constructive discussion here that more than just I can learn from. I appreciate any responses and hope to hear from you. Thanks!

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• Simplifying Testing through design considerations while utilizing dependency injection

  - by Adam Driscoll

  We are a few months into a green-field project to rework the Logic and Business layers of our product. By utilizing MEF (dependency injection) we have achieved high levels of code coverage and I believe that we have a pretty solid product. As we have been working through some of the more complex logic I have found it increasingly difficult to unit test. We are utilizing the CompositionContainer to query for types required by these complex algorithms. My unit tests are sometimes difficult to follow due to the lengthy mock object setup process that must take place, just right, to allow for certain circumstances to be verified. My unit tests often take me longer to write than the code that I'm trying to test. I realize this is not only an issue with dependency injection but with design as a whole. Is poor method design or lack of composition to blame for my overly complex tests? I've tried base classing tests, creating commonly used mock objects and ensuring that I utilize the container as much as possible to ease this issue but my tests always end up quite complex and hard to debug. What are some tips that you've seen to keep such tests concise, readable, and effective?

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• What is the base open source java package to filter/match URLs?

  - by Boaz

  Hi, I have an high performance application which deals with URLs. For every URL it needs to retrieve the appropriate settings from a predefined pool. Every settings object is associated with a URL pattern which indicates which URLs should use these settings. The matching rules are as follows: "google.com" match pattern should match all URLs pointing to the google domain (thus, maps.google.com and www.google.com/match are matched). "*.google.com" should match all URLs pointing to a subdomain of google.com (thus, maps.google.com matches, but google.com and www.google.com don't). "maps.google.com" should match all URLs pointing to this specific subdomain. Apart from the above rules, every match rule can contain a path, which means that the path part of the URL should start with the match rule path. So: "*.google.com/maps" matches "maps.google.com/maps" but not "maps.google.com/advanced". As you can see the rules above are overlapping. In the case two rules exist which match the same URL the most specific should apply. The list above is ranked from least specific to most specific. This seems to be such a standard problem that I was hoping to use a ready made library rather than program my self. Google reveals a couple of options but without a clear way to choose between them. What would you recommend as a good library for this task? Thanks, Boaz

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• Transform only one axis to log10 scale with ggplot2

  - by daroczig

  I have the following problem: I would like to visualize a discrete and a continuous variable on a boxplot in which the latter has a few extreme high values. This makes the boxplot meaningless (the points and even the "body" of the chart is too small), that is why I would like to show this on a log10 scale. I am aware that I could leave out the extreme values from the visualization, but I am not intended to. Let's see a simple example with diamonds data: m <- ggplot(diamonds, aes(y = price, x = color)) The problem is not serious here, but I hope you could imagine why I would like to see the values at a log10 scale. Let's try it: m + geom_boxplot() + coord_trans(y = "log10") As you can see the y axis is log10 scaled and looks fine but there is a problem with the x axis, which makes the plot very strange. The problem do not occur with scale_log, but this is not an option for me, as I cannot use a custom formatter this way. E.g.: m + geom_boxplot() + scale_y_log10() My question: does anyone know a solution to plot the boxplot with log10 scale on y axis which labels could be freely formatted with a formatter function like in this thread? Editing the question to help answerers based on answers and comments: What I am really after: one log10 transformed axis (y) with not scientific labels. I would like to label it like dollar (formatter=dollar) or any custom format. If I try @hadley's suggestion I get the following warnings: > m + geom_boxplot() + scale_y_log10(formatter=dollar) Warning messages: 1: In max(x) : no non-missing arguments to max; returning -Inf 2: In max(x) : no non-missing arguments to max; returning -Inf 3: In max(x) : no non-missing arguments to max; returning -Inf With an unchanged y axis labels:

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• ISO/IEC Website and Charging for C and C++ Standards

  - by Michael Aaron Safyan

  The ISO C Standard (ISO/IEC 9899) and the ISO C++ Standard (ISO/IEC 14882) are not published online; instead, one must purchase the PDF for each of those standards. I am wondering what the rationale is behind this... is it not detrimental to both the C and C++ programming languages that the authoritative specification for these languages is not made freely available and searchable online? Doesn't this encourage the use of possibly inaccurate, non-authoritative sources for information regarding these standards? While I understand that much time and effort has gone into developing the C and C++ standards, I am still somewhat puzzled by the choice to charge for the specification. The OpenGroup Base Specification, for example, is available for free online; they make money buy charging for certification. Does anyone know why the ISO standards committees don't make their revenue in certifying standards compliance, instead of charging for these documents? Also, does anyone know if the ISO standards committee's atrociously looking website is intentionally made to look that way? It's as if they don't want people visiting and buying the spec. One last thing... the C and C++ standards are generally described as "open standards"... while I realize that this means that anyone is permitted to implement the standard, should that definition of "open" be revised? Charging for the standard rather than making it openly available seems contrary to the spirit of openness. P.S. I do have a copy of the ISO/IEC 9899:1999 and ISO/IEC 14882:2003, so please no remarks about being cheap or anything... although if you are tempted to say such things, you might want to consider the high school, undergraduate, and graduate students who might not have all that much extra cash. Also, you might want to consider the fact that the ISO website is really sketchy and they don't even tell you the cost until you proceed to the checkout... doesn't really encourage one to go and get a copy, now does it?

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• Can't send smtp email from network using C#, asp.net website

  - by Kaysar

  Hi, I have my code here, it works fine from my home, where my user is administrator, and I am connected to internet via a cable network. But, problem is when I try this code from my work place, it does not work. Shows error: "unable to connect to the remote server" From a different machine in the same network: "A socket operation was attempted to an unreachable network 209.xxx.xx.52:25" I checked with our network admin, and he assured me that all the mail ports are open [25,110, and other ports for gmail]. Then, I logged in with administrative privilege, there was a little improvement, it did not show any error, but the actual email was never received. Please note that, the code was tested from development environment, visual studio 2005 and 2008. Any suggestion will be much appreciated. Thanks in advance try { MailMessage mail_message = new MailMessage("[email protected]", txtToEmail.Text, txtSubject.Text, txtBody.Text); SmtpClient mail_client = new SmtpClient("SMTP.y7mail.com"); NetworkCredential Authentic = new NetworkCredential("[email protected]", "xxxxx"); mail_client.UseDefaultCredentials = true; mail_client.Credentials = Authentic; mail_message.IsBodyHtml = true; mail_message.Priority = MailPriority.High; try { mail_client.Send(mail_message); lblStatus.Text = "Mail Sent Successfully"; } catch (Exception ex) { System.Diagnostics.Debug.WriteLine(ex.Message); lblStatus.Text = "Mail Sending Failed\r\n" + ex.Message; } } catch (Exception ex) { lblStatus.Text = "Mail Sending Failed\r\n" + ex.Message; }

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• Why does adding Crossover to my Genetic Algorithm give me worse results?

  - by MahlerFive

  I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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• R : remove columns from dataframe where ALL values are NA

  - by Sophomore

  hello everybody! I'm having some trouble with my huge data frame and couldn't really resolve that question myself: The dataframe has some properties as columns and each row represents one data set. I've done some sanatizing to this dataframe (e.g. get rid of datasets which are not to be included in evaluation). (Whoever might be interested: Beforehand I aggregate around 5000 single text files and put them in a tsv, some of the proerties have a sequence number like "button.pressed.1" ... ""button.pressed.n". Some of the sets excluded had really high numbers for n but got excluded, all sets left have much smaller numbers for n but the property "button.presed.50" is still there and all remaining sets have an NA in that column. Actually its a different property but the example should clarify my intention...) So the question is quite simple (for some sophisticated R pro): I need to get rid of columns where for ALL rows the value is NA. Could someone please help me out? (All I have managed to get rid of columns where at least one NA exists which dropped about half my columns)...

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• Netlogo: error when putting variable in table, only constants allowe??

  - by Chantal

  Hello, Currently I am working on a Netlogo program where I need to use nodes and links for vehicle routing problem. (links are called streets in the program) Here I have some practical problems of how to input variable linkspeed in a table with another node. Constants like 200 etc are fine. Online I found some examples where variables are used, but I do not know why I keep getting the following error: Expected a constant. (or why netlogo expects a constant) Here is the relevant piece of code: extensions [table] streets-own [linkspeed linktoll] nodes-own [netw] ;; In another piece of code linkspeed is assigned successfully to the links to cheapcalc ;; start conditions set costs very high 300000 ;; state 3 unsearched state 2 searching state 1 searched (for later purposes) ask nodes [ set i 0 set j count nodes set netw table:make while [i < j][ table:put netw (i) [3000000 3] set i (i + 1)]] set i 0 let k 0 ask node 35 ;; here i use node 35 as an example. ;; node 35 is connected to node 34, 36, 20 and 50 [table:put netw (35) [0 1] ;; node need to search costs to travel to itself ;; putting constants is ok. while [i < j] [ask my-links [ask both-ends [if (who != 35) [set color blue ;; set temp ([linkspeed] of street 35 who) ;; here my real goal is to put this in stat of i. but i is easier than linkspeed. table:put netw (who) [ i 2 ] ] ] ] set i (i + 1)] ] ;; next node for later, no it is just repetition of the same. end I hope somebody knows what is going on... Kind regards, Chantal

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