Search Results

Search found 6945 results on 278 pages for 'azure use cases'.

Page 224/278 | < Previous Page | 220 221 222 223 224 225 226 227 228 229 230 231  | Next Page >

• Different Scala Actor Implementations Overview

  - by Stefan K.

  I'm trying to find the 'right' actor implementation for my thesis. I realized there is a bunch of them and it's a bit confusing to pick one. Personally I'm especially interested in remote actors, but I guess a complete overview would be helpful to many others. This is a pretty general question, so feel free to answer just for the implementation you know about. I know about the following Scala Actor implementations (SAI). Please add the missing ones. Scala 2.7 (difference to) Scala 2.8 Akka (http://www.akkasource.org/) Lift (http://liftweb.net/) Scalaz (http://code.google.com/p/scalaz/) What are the target use-cases for these SAIs (lightweight vs. "heavy" enterprise framework)? do they support remote actors? What shortcomings do remote actors have in the SAIs? How is their performace? How active is there community? How easy are they to get started? How good is the documentation? How easy are they to extend? How stable are they? Which projects are using them? What are their shortcomings? What are their design principles? Are they thread based or event based (receive/ react) or both? Nested receiveS hotswapping the Actor’s message loop

  Read the article

• Suppressing PostSharp Multicast with Attribute

  - by Dan Bryant

  I've recently started experimenting with PostSharp and I found a particularly helpful aspect to automate implementation of INotifyPropertyChanged. You can see the example here. The basic functionality is excellent (all properties will be notified), but there are cases where I might want to suppress notification. For instance, I might know that a particular property is set once in the constructor and will never change again. As such, there is no need to emit the code for NotifyPropertyChanged. The overhead is minimal when classes are not frequently instantiated and I can prevent the problem by switching from an automatically generated property to a field-backed property and writing to the field. However, as I'm learning this new tool, it would be helpful to know if there is a way to tag a property with an attribute to suppress the code generation. I'd like to be able to do something like this: [NotifyPropertyChanged] public class MyClass { public double SomeValue { get; set; } public double ModifiedValue { get; private set; } [SuppressNotify] public double OnlySetOnce { get; private set; } public MyClass() { OnlySetOnce = 1.0; } }

  Read the article

• should the builder reset its build environment after delivering the product

  - by Sudhi

  I am implementing a builder where in the deliverable is retrieved by calling Builder::getProduct() . The director asks various parts to build Builder::buildPartA() , Builder::buildPartB() etc. in order to completely build the product. My question is, once the product is delivered by the Builder by calling Builder::getProduct(), should it reset its environment (Builder::partA = NULL;, Builder::partB = NULL;) so that it is ready to build another product? (with same or different configuration?) I ask this as I am using PHP wherein the objects are by default passed by reference (nope, I don't want to clone them, as one of their field is a Resource) . However, even if you think from a language agnostic point of view, should the Builder reset its build environment ? If your answer is 'it depends on the case' what use cases would justify reseting the environment (and other way round) ? For the sake of providing code sample here's my Builder::gerProcessor() which shows what I mean by reseting the environment /** * @see IBuilder::getProessor() */ public function getProcessor() { if($this->_processor == NULL) { throw new LogicException('Processor not yet built!'); } else { $retval = $this->_processor; $this->_product = NULL, $this->_processor = NULL; } return $retval; }

  Read the article

• C/C++ Control Structure Limitations?

  - by STingRaySC

  I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

  Read the article

• Cant' cast a class with multiple inheritance

  - by Jay S.

  I am trying to refactor some code while leaving existing functionality in tact. I'm having trouble casting a pointer to an object into a base interface and then getting the derived class out later. The program uses a factory object to create instances of these objects in certain cases. Here are some examples of the classes I'm working with. // This is the one I'm working with now that is causing all the trouble. // Some, but not all methods in NewAbstract and OldAbstract overlap, so I // used virtual inheritance. class MyObject : virtual public NewAbstract, virtual public OldAbstract { ... } // This is what it looked like before class MyObject : public OldAbstract { ... } // This is an example of most other classes that use the base interface class NormalObject : public ISerializable // The two abstract classes. They inherit from the same object. class NewAbstract : public ISerializable { ... } class OldAbstract : public ISerializable { ... } // A factory object used to create instances of ISerializable objects. template<class T> class Factory { public: ... virtual ISerializable* createObject() const { return static_cast<ISerializable*>(new T()); // current factory code } ... } This question has good information on what the different types of casting do, but it's not helping me figure out this situation. Using static_cast and regular casting give me error C2594: 'static_cast': ambiguous conversions from 'MyObject *' to 'ISerializable *'. Using dynamic_cast causes createObject() to return NULL. The NormalObject style classes and the old version of MyObject work with the existing static_cast in the factory. Is there a way to make this cast work? It seems like it should be possible.

  Read the article

• questions about name mangling in C++

  - by Tim

  I am trying to learn and understand name mangling in C++. Here are some questions: (1) From devx When a global function is overloaded, the generated mangled name for each overloaded version is unique. Name mangling is also applied to variables. Thus, a local variable and a global variable with the same user-given name still get distinct mangled names. Are there other examples that are using name mangling, besides overloading functions and same-name global and local variables ? (2) From Wiki The need arises where the language allows different entities to be named with the same identifier as long as they occupy a different namespace (where a namespace is typically defined by a module, class, or explicit namespace directive). I don't quite understand why name mangling is only applied to the cases when the identifiers belong to different namespaces, since overloading functions can be in the same namespace and same-name global and local variables can also be in the same space. How to understand this? Do variables with same name but in different scopes also use name mangling? (3) Does C have name mangling? If it does not, how can it deal with the case when some global and local variables have the same name? C does not have overloading functions, right? Thanks and regards!

  Read the article

• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

  Read the article

• Code-Golf: one line PHP syntax

  - by Kendall Hopkins

  Explanation PHP has some holes in its' syntax and occasionally in development a programmer will step in them. This can lead to much frustration as these syntax holes seem to exist for no reason. For example, one can't easily create an array and access an arbitrary element of that array on the same line (func1()[100] is not valid PHP syntax). The workaround for this issue is to use a temporary variable and break the statement into two lines, but sometimes that can lead to very verbose, clunky code. Challenge I know of a few of these holes (I'm sure there are more). It is quite hard to even come up with a solution, let alone in a code-golf style. Winner is the person with in the least characters total for all four Syntax Holes. Rules Statement must be one line in this form: $output = ...;, where ... doesn't contain any ;'s. Only use standard library functions (no custom functions allowed) Statement works identically to the assumed functional of the non-working syntax (even in cases that it fails). Statement must run without syntax error of any kind with E_STRICT | E_ALL. Syntax Holes $output = func_return_array()[$key]; - accessing an arbitrary offset (string or integer) of the returned array of a function $output = new {$class_base.$class_suffix}(); - arbitrary string concatenation being used to create a new class $output = {$func_base.$func_suffix}(); - arbitrary string concatenation being called as function $output = func_return_closure()(); - call a closure being returned from another function

  Read the article

• how to conditional display a control in asp wizard based on the radiobutton click in a particular st

  - by Pramod

  Hi, I've been stuck with this problem where there are 3 steps in an asp wizard control. The first step has a radiobutton (yes and no) and based on the radio button input chosen by the user, i would need to hide or show a label in the second wizardstep. Example: Step 1: Choose 1 among the two options: Yes No (radStep1) Step 2: if the radiobutton option in the previous step was yes.. then display a label(lblStep2) in this step.. Else hide the label. I've been handling this through the jquery as i want the functionality in the aspx page itself... The jquery code goes like this... $("#<%=radStep1.ClientID %> input").click(function() { if($("#<%= radStep1.ClientID %> input").index(this) == 0) { $("#<%=lblStep2.ClientID %>").show(); } else if($("#<%= radStep1.ClientID %> input").index(this) == 1) { $("#<%=lblStep2.ClientID %>").hide(); } However, in both the cases, the label is getting displayed.. Could you please help me out if there is anything that i'm missing? I'm guessing that the label is getting hidden at first and then getting shown again once i click on the next button... Thanks a ton in advance....

  Read the article

• Are document-oriented databases any more suitable than relational ones for persisting objects?

  - by Owen Fraser-Green

  In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

  Read the article

• Image resizing - sometimes very poor quality?!

  - by eWolf

  I'm resizing some images to the screen resolution of the user; if the aspect ratio is wrong, the image should be cut. My code looks like this: protected void ConvertToBitmap(string filename) { var origImg = System.Drawing.Image.FromFile(filename); var widthDivisor = (double)origImg.Width / (double)System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width; var heightDivisor = (double)origImg.Height / (double)System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height; int newWidth, newHeight; if (widthDivisor < heightDivisor) { newWidth = (int)((double)origImg.Width / widthDivisor); newHeight = (int)((double)origImg.Height / widthDivisor); } else { newWidth = (int)((double)origImg.Width / heightDivisor); newHeight = (int)((double)origImg.Height / heightDivisor); } var newImg = origImg.GetThumbnailImage(newWidth, newHeight, null, IntPtr.Zero); newImg.Save(this.GetBitmapPath(filename), System.Drawing.Imaging.ImageFormat.Bmp); } In most cases, this works fine. But for some images, the result has an extremely poor quality. It looks like the would have been resized to something very small (thumbnail size) and enlarged again.. But the resolution of the image is correct. What can I do? Example orig image: Example resized image: Note: I have a WPF application but I use the WinForms function for resizing because it's easier and because I already need a reference to System.Windows.Forms for a tray icon.

  Read the article

• Does SetFileBandwidthReservation affect memory-mapped file performance?

  - by Ghostrider

  Does this function affect Memory-mapped file performance? Here's the problem I need to solve: I have two applications competing for disk access: "reader" and "updater". Whole system runs on Windows Server 2008 R2 x64 "Updater" constantly accesses disk in a linear manner, updating data. They system is set up in such a way that updater always has infinite data to update. Consider that it is constantly approximating a solution of a huge set of equations that takes up entire 2TB disk drive. Updater uses ReadFile and WriteFile to process data in a linear fashion. "Reader" is occasionally invoked by user to get some pieces of data. Usually user would read several 4kb blocks from the drive and stop. Occasionally user needs to read up to 100mb sequentially. In exceptional cases up to several gigabytes. Reader maps files to memory to get data it needs. What I would like to achieve is for "reader" to have absolute priority so that "updater" would completely stop if needed so that "reader" could get the data user needs ASAP. Is this problem solvable by using SetPriorityClass and SetFileBandwidthReservation calls? I would really hate to put synchronization login in "reader" and "updater" and rather have the OS take care of priorities.

  Read the article

• Compiling Objective-C project on Linux (Ubuntu)

  - by Alex

  How to make an Objective-C project work on Ubuntu? My files are: Fraction.h #import <Foundation/NSObject.h> @interface Fraction: NSObject { int numerator; int denominator; } -(void) print; -(void) setNumerator: (int) n; -(void) setDenominator: (int) d; -(int) numerator; -(int) denominator; @end Fraction.m #import "Fraction.h" #import <stdio.h> @implementation Fraction -(void) print { printf( "%i/%i", numerator, denominator ); } -(void) setNumerator: (int) n { numerator = n; } -(void) setDenominator: (int) d { denominator = d; } -(int) denominator { return denominator; } -(int) numerator { return numerator; } @end main.m #import <stdio.h> #import "Fraction.h" int main( int argc, const char *argv[] ) { // create a new instance Fraction *frac = [[Fraction alloc] init]; // set the values [frac setNumerator: 1]; [frac setDenominator: 3]; // print it printf( "The fraction is: " ); [frac print]; printf( "\n" ); // free memory [frac release]; return 0; } I've tried two approaches to compile it: Pure gcc: $ sudo apt-get install gobjc gnustep gnustep-devel $ gcc `gnustep-config --objc-flags` -o main main.m -lobjc -lgnustep-base /tmp/ccIQKhfH.o:(.data.rel+0x0): undefined reference to `__objc_class_name_Fraction' I created a GNUmakefile Makefile: include ${GNUSTEP_MAKEFILES}/common.make TOOL_NAME = main main_OBJC_FILES = main.m include ${GNUSTEP_MAKEFILES}/tool.make ... and ran: $ source /usr/share/GNUstep/Makefiles/GNUstep.sh $ make Making all for tool main... Linking tool main ... ./obj/main.o:(.data.rel+0x0): undefined reference to `__objc_class_name_Fraction' So in both cases compiler gets stuck at undefined reference to `__objc_class_name_Fraction' Do you have and idea how to resolve this issue?

  Read the article

• Closing the gap between 2 inline elements

  - by insanepaul

  I have a simple div element that contains 2 inline tags. I've associated a onmouseout event to the div element. The problem is that the onmouseout event is fired when the user hovers their mouse between the two tags in the div and also after the end of the second tag. What I want to do is allow the user to hover their mouse across the whole of the div tag and only fire the onmouseout event when the mouse pointer is outside the div element (which is what I assumed from what I've done). I increased padding to close the gap between the 2 tags. This works but where they meet in IE7 at least the event is fired!!! I must be doing something wrong can someone please help. <div id="Div1" onmouseover="hideDiv()"> <a id="A1" href="HTMLNew.htm">ARTICLES</a> <a id="A2" href="HTMLNew.htm">COURSES & CASES</a> </div>

  Read the article

• Conventions for the behavior of double or triple "click to select text" features?

  - by John Sullivan

  Almost any mature program that involves text implements "double click to select the word" and, in some cases, "triple click to select additional stuff like an entire line" as a feature. I find these features useful but they are often inconsistent between programs. Example - some programs' double clicks do not select the ending space after a word, but most do. Some recognize the - character as the end of a word, others do not. SO likes to select the entire paragraph as I write this post when I triple click it, VS web developer 2005 has no triple click support, and ultra-edit 32 will select one line upon triple clicking. We could come up with innumerable inconsistencies about how double and triple click pattern matching is implemented across programs. I am concerned about how to implement this behavior in my program if nobody else has achieved a convention about how the pattern matching should work. My question is, does a convention (conventions? maybe an MS or Linux convention?) exist that dictates how these features are supposed to behave to the end user? What, if any, are they?

  Read the article

• m2eclipse: How to set Eclipse project settings when importing a maven project?

  - by Marius Andreiana

  Using m2eclipse Eclipse plugin, everybody on the dev team should be able to checkout source code, import Maven project in Eclipse and be good to go. I saw m2eclipse is being merged into Eclipse 3.7, and maven-eclipse-plugin won't be maintained any longer, so I'm looking for a m2eclipse-based solution (without running "mvn eclipse:clean eclipse:eclipse" before project import, which is what maven-eclipse-plugin does). maven-eclipse-plugin allows this in pom.xml <additionalConfig> <file> <name>.settings/com.google.gdt.eclipse.core.prefs</name> <content><![CDATA[ eclipse.preferences.version=2 jarsExcludedFromWebInfLib= warSrcDir=${project.build.directory}/${project.build.finalName} warSrcDirIsOutput=true ]]> </content> </file> The more general question is How would m2eclipse do something similar? For some cases, just saving the eclipse .settings/prefs file works (e.g. org.eclipse.jdt.ui.prefs), but in this case, com.google.gdt.eclipse.core.prefs is always overwritten on m2eclipse project import. A specific question is asked here, with no reply. Thanks! UPDATE: Not possible now, see request

  Read the article

• When to choose which machine learning classifier?

  - by LM

  Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

  Read the article

• Why does C++ not allow multiple types in one auto statement?

  - by Walter

  The 2011 C++ standard introduced the new keyword auto, which can be used for defining variables instead of a type, i.e. auto p=make_pair(1,2.5); // pair<int,double> auto i=std::begin(c), end=std::end(c); // decltype(std::begin(c)) In the second line, i and end are of the same type, referred to as auto. The standard does not allow auto i=std::begin(container), e=std::end(container), x=*i; when x would be of different type. My question: why does the standard not allow this last line? It could be allowed by interpreting auto not as representing some to-be-decuded type, but as indicating that the type of any variable declared auto shall be deduced from its assigned value. Is there any good reason for the C++11 standard to not follow this approach? There is actually a use case for this, namely in the initialisation statement of for loops: for(auto i=std::begin(c), end=std::end(c), x=*i; i!=end; ++i, x+=*i) { ... } when the scope of the variables i, end, and x is limited to the for loop. AFAIK, this cannot be achieved in C++ unless those variables have a common type. Is this correct? (ugly tricks of putting all types inside a struct excluded) There may also be use cases in some variadic template applications.

  Read the article

• using an alternative string quotation syntax in python

  - by Cawas

  Just wondering... I find using escape characters too distracting. I'd rather do something like this: print ^'Let's begin and end with sets of unlikely 2 chars and bingo!'^ Let's begin and end with sets of unlikely 2 chars and bingo! Note the ' inside the string, and how this syntax would have no issue with it, or whatever else inside for basically all cases. Too bad markdown can't properly colorize it (yet), so I decided to <pre> it. Sure, the ^ could be any other char, I'm not sure what would look/work better. That sounds good enough to me, tho. Probably some other language already have a similar solution. And, just maybe, Python already have such a feature and I overlooked it. I hope this is the case. But if it isn't, would it be too hard to, somehow, change Python's interpreter and be able to select an arbitrary (or even standardized) syntax for notating the strings? I realize there are many ways to change statements and the whole syntax in general by using pre-compilators, but this is far more specific. And going any of those routes is what I call "too hard". I'm not really needing to do this so, again, I'm just wondering.

  Read the article

• Join two tables with same # of row but sorted for NULL

  - by VISQL

  I need to join two tables with the same number of rows. Each table has 1 column. There is NO CONNECTING COLUMN to reference for a join. I need to join them side by side because each table was sorted separately so that numeric values are at the top in descinding order. The Table Earners has income values from say 200K down to 0. I cannot just select using 2 cases, because then I will have my first row with Incomes above 100K, but the first 20 or so entries in the second row are NULL. I want the second row to also be sorted descending. I looked up using ORDER BY within CASE but there is no such thing. I have tried to read about row_number() but none of the examples seem to match or make sense. drop table #20plus select case when Income >= 20000 AND Income < 100000 then Income end as 'mula' into #20plus from Earners order by mula desc drop table #100plus select case when Income >= 100000 then Income end as 'dinero' into #100plus from Earners order by dinero desc Select A.dinero, B.mula FROM #100plus as A JOIN #20plus as B ON A.????? = B.????? Since both A and B are sorted descending, moving all NULL to the bottom, what can I reference to join the two tables? Previous output using one SELECT statement with 2 CASE statements dinero mula 2.12688e+007 NULL 1.80031e+007 NULL 1.92415e+006 NULL … … NULL 93530.7 NULL 91000 NULL 84500 Desired output using one SELECT statement after creating two temp TABLES dinero mula 2.12688e+007 93530.7 1.80031e+007 91000 1.92415e+006 84500 … 82500 NULL 82000 NULL … NULL NULL This is Microsoft SQL Server 2008. I'm super new to this, so please give an answer as clear and simplified as possible. Thank you.

  Read the article

• Accelerometer gravity components

  - by Dvd

  Hi, I know this question is definitely solved somewhere many times already, please enlighten me if you know of their existence, thanks. Quick rundown: I want to compute from a 3 axis accelerometer the gravity component on each of these 3 axes. I have used 2 axes free body diagrams to work out the accelerometer's gravity component in the world X-Z, Y-Z and X-Y axes. But the solution seems slightly off, it's acceptable for extreme cases when only 1 accelerometer axis is exposed to gravity, but for a pitch and roll of both 45 degrees, the combined total magnitude is greater than gravity (obtained by Xa^2+Ya^2+Za^2=g^2; Xa, Ya and Za are accelerometer readings in its X, Y and Z axis). More detail: The device is a Nexus One, and have a magnetic field sensor for azimuth, pitch and roll in addition to the 3-axis accelerometer. In the world's axis (with Z in the same direction as gravity, and either X or Y points to the north pole, don't think this matters much?), I assumed my device has a pitch (P) on the Y-Z axis, and a roll (R) on the X-Z axis. With that I used simple trig to get: Sin(R)=Ax/Gxz Cos(R)=Az/Gxz Tan(R)=Ax/Az There is another set for pitch, P. Now I defined gravity to have 3 components in the world's axis, a Gxz that is measurable only in the X-Z axis, a Gyz for Y-Z, and a Gxy for X-Y axis. Gxz^2+Gyz^2+Gxy^2=2*G^2 the 2G is because gravity is effectively included twice in this definition. Oh and the X-Y axis produce something more exotic... I'll explain if required later. From these equations I obtained a formula for Az, and removed the tan operations because I don't know how to handle tan90 calculations (it's infinity?). So my question is, anyone know whether I did this right/wrong or able to point me to the right direction? Thanks! Dvd

  Read the article

• I seek a PDF paginator

  - by Cameron Laird

  More precisely, I need software that will allow me to consume existing PDF instances, decorate them with page numbers, or page-number-like writing, then write them back to the filesystem. I'll happily pay for an application, or program it myself. I almost certainly require the software run under Linux (Ubuntu, more specifically). iText comes close. iText certainly can read existing PDF instances. While iText is, for this purpose, only a library, and requires me to program a tiny amount to specify where on the page the numbers should appear, I'm happy to do that. I hesitate with iText only because the latest iText license is a headache at certain government agencies (in practice, I'd probably request and pay for a special license), and because, over the last few years, I've observed cases where iText doesn't appear to keep up with the standard, that is, it has more troubles than I expect reading PDFs observed "in the wild". Similarly, every other possibility I know has at least one difficulty: ReportLab would likely require a disproportionate licensing fee for the small value it provides in this situation, and so on. This application requires no particular sophistication with Unicode, fonts, ... I recognize there are plenty of executables and libraries that do some or all of what I require. I welcome any tips on software that is reliable, generally current with PDF practice, flexible/programmable/configurable/..., and "automatable". In the absence of any new insight, I'll likely go with a specific open-source library I don't want to mention now for which I've already contracted enhancements, or perhaps revisit iText.

  Read the article

• The fastest way to iterate through a collection of objects

  - by Trev

  Hello all, First to give you some background: I have some research code which performs a Monte Carlo simulation, essential what happens is I iterate through a collection of objects, compute a number of vectors from their surface then for each vector I iterate through the collection of objects again to see if the vector hits another object (similar to ray tracing). The pseudo code would look something like this for each object { for a number of vectors { do some computations for each object { check if vector intersects } } } As the number of objects can be quite large and the amount of rays is even larger I thought it would be wise to optimise how I iterate through the collection of objects. I created some test code which tests arrays, lists and vectors and for my first test cases found that vectors iterators were around twice as fast as arrays however when I implemented a vector in my code in was somewhat slower than the array I was using before. So I went back to the test code and increased the complexity of the object function each loop was calling (a dummy function equivalent to 'check if vector intersects') and I found that when the complexity of the function increases the execution time gap between arrays and vectors reduces until eventually the array was quicker. Does anyone know why this occurs? It seems strange that execution time inside the loop should effect the outer loop run time.

  Read the article

• Should I write more SQL to be more efficient, or less SQL to be less buggy?

  - by RenderIn

  I've been writing a lot of one-off SQL queries to return exactly what a certain page needs and no more. I could reuse existing queries and issue a number of SQL requests linear to the number of records on the page. As an example, I have a query to return People and a query to return Job Details for a person. To return a list of people with their job details I could query once for people and then once for each person to retrieve their job details. I've found that in most cases that solution returns things in a reasonable amount of time, but I don't know how well it will scale in my environment. Instead I've been writing queries to join people + job details, or people + salary history, etc. I'm looking at my models and I see how I could shave off maybe 30% of my code if I were to re-use existing queries. This is a big temptation. Is it a bad thing to go for reuse over efficiency in general or does it all come down to the specific situation? Should I first do it the easy way and then optimize later, or is it best to get the code knocked out while everything is fresh in my mind? Thoughts, experiences?

  Read the article

• Prototypal inheritance should save memory, right?

  - by Techpriester

  Hi Folks, I've been wondering: Using prototypes in JavaScript should be more memory efficient than attaching every member of an object directly to it for the following reasons: The prototype is just one single object. The instances hold only references to their prototype. Versus: Every instance holds a copy of all the members and methods that are defined by the constructor. I started a little experiment with this: var TestObjectFat = function() { this.number = 42; this.text = randomString(1000); } var TestObjectThin = function() { this.number = 42; } TestObjectThin.prototype.text = randomString(1000); randomString(x) just produces a, well, random String of length x. I then instantiated the objects in large quantities like this: var arr = new Array(); for (var i = 0; i < 1000; i++) { arr.push(new TestObjectFat()); // or new TestObjectThin() } ... and checked the memory usage of the browser process (Google Chrome). I know, that's not very exact... However, in both cases the memory usage went up significantly as expected (about 30MB for TestObjectFat), but the prototype variant used not much less memory (about 26MB for TestObjectThin). I also checked: The TestObjectThin instances contain the same string in their "text" property, so they are really using the property of the prototype. Now, I'm not so sure what to think about this. The prototyping doesn't seem to be the big memory saver at all. I know that prototyping is a great idea for many other reasons, but I'm specifically concerned with memory usage here. Any explanations why the prototype variant uses almost the same amount of memory? Am I missing something?

  Read the article

< Previous Page | 220 221 222 223 224 225 226 227 228 229 230 231  | Next Page >