Search Results

Search found 1348 results on 54 pages for 'floating accuracy'.

Page 42/54 | < Previous Page | 38 39 40 41 42 43 44 45 46 47 48 49  | Next Page >

  • Why is my Mac not displaying anything to my LCD tv using HDMI?

    - by Pure.Krome
    Hi folks, I've got an iMac desktop computer. Love it. I wish to connect it to my LCD TV using HDMI. There is no HDMI output on the iMac so i had to buy one of these bad boys :- so now I can output video (via the mini Display Port) and sound (via USB) through this box, to my LCD. Works great ... with a single direct cable. I have another 3 or 5 metre cable inserted into my wall, so i do not have to have a silly hdmi cable floating in the air between my iMac and my LCD TV. When I do this, there is no picture. To better explain all of this, i made a quick video explaining my problem in detail, so you can exactly see what is going on/wrong. I've also tried changing the output format for the TV from 1080i down to 720p and even lower .. incase the cable in the wall doesn't allow 1080i. here's the video with the full explanation :- http://www.youtube.com/watch?v=ZkKRKnRIh6Q (NOTE: I incorrectly said in the video that the hidden wall cable is 10 metres long. me == fail. It's 3m or 5m...). Can someone please watch it and suggest some ideas to getting it working?

    Read the article

  • Preserve embedded album art when converting from .flac to .ogg

    - by Profpatsch
    I want to convert my archived .flac library to .ogg for daily use. Using find ./ -iname '*.flac' -print0 | xargs -0 -n1 oggenc -q6 on the root music folder and then deleting every .flac (having copies of them in archive) seems straight forward, after trying it with one file it worked and all of the tags were transfered, too, except for one: Embedded album art! I always prefer emedded covers over folder images, since I have some albums with varying covers. One possible solution is discussed here, but the script only works if the image is already extracted: Embed album art in OGG through command line in linux One possible solution I thought about was extracting album art from every song (not every song has one, though, and some even 2 or 3!), temporarily saving it and then using the script to include it into the finished .ogg. But then I want to increase the number of processes xargs runs simultaniously to save time, so the temp images need to have a distinct name. Is there a (linux) program that knows how to handle this? Or is there a finished script floating around somewhere? It would be nice if oggenc supported adding embedded coverart and it really is a shame, since these two formats should (in theory) share the same tag format. Edit: 15 days and noone even tries to answer. It’s funny, most of my questions don’t get answered. Too hard? Wrong SE site?

    Read the article

  • PC dies when running at 100% CPU

    - by user155631
    I recently wrote some Java code to generate images of the Mandelbrot set (fractal). I made use of the new Fork/Join facility in Java 7 to run separate threads on all four cores (2 real, 2 virtual)simultaneously, using a large number of iterations for greater accuracy. The problem is, the process runs fine for about a minute, and then it's as if someone has pulled the plug and the PC just dies. I thought it must be the CPUs overheating, so I ran Real Temp to monitor the temperature. It's an Intel i3 processor. I can see the temperature creeping up to 70 degrees, and then it seems to level off there and run for about another 30 seconds before dying. According to Real Temp, there's still a gap of 35 degrees between the actual temperature and TJ max. I also tried disabling "CPU TM function" in the BIOS, but the problem still occurs. A colleague suggested that it might be a power supply problem, so I borrowed a more powerful PSU (can't remember what wattage it was, but it's higher than mine which is 500W). The exact same thing still happens though. Is anyone able to suggest what the problem might be, or what I can try next?

    Read the article

  • Managing SharePoint permissions via Active Directory?

    - by rgmatthes
    My company has thousands of employees organized thoroughly via Active Directory. I have confidence in the accuracy of the Department and Title information displayed in the user profiles. I'm helping to put up a brand new SharePoint 2007 site, and I contacted IT about managing the site's permissions through AD Groups. The goal is to have the site automatically assign read/write/contribute/whatever permissions based on the information in AD. For example, we could create an AD Group called "Managers" that would contain anyone with the "Manager" title in their AD user profile. I would have SharePoint tap into this AD Group to mass assign permissions if I knew all managers would need a certain level of access (read/write/contribute/whatever). Then if a manager joins the company or leaves it, the group is automatically updated (provided AD gets updated, of course). My IT rep called back and said it couldn't be done. This seems like a pretty straightforward business requirement, and one of the huge benefits of having Active Directory, but maybe I'm mistaken. Could anyone shed some light on this? A) Is it possible to use dynamically-updated AD Groups when assigning permissions via SharePoint? (Does anyone know of a guide I could show my doubtful IT rep?) B) Is there a "best practice" way to go about this? I've read some debate on whether SharePoint Groups or AD Groups are the way to go. My main concern is dynamic updating. C) If this isn't available out of the box, can someone recommend third-party software that will provide the functionality I'm looking for? A big thanks to anyone who can help me out!!

    Read the article

  • Postgresql Data Aggregation over WAN Securely

    - by Zach
    Hey guys, Need some advice on how to proceed with this situation: My current scenario is that I have several postgresql (50+) boxes deployed throughout various locations and data centers and a beefy postgresql box setup at a homebase location. All of the deployed boxes have identical database layouts. I'm looking for a solution that would allow for a few things. I realize some of these options overlap and some might only contain mutually exclusive solutions. However, I'm interested to hear your thoughts :) Remotely query the deployed boxes and pull the results back to the homebase box for processing. Nightly (remote) "sync" or dump the deployed boxes' databases to a master database on the homebase box. Remotely push a table entry to all of the deployed boxes from the homebase box. Ensure security of data in transit, and remotely deployed boxes. Up to this point I've been floating on a homebrew multithreaded python/perl system that SSH's into these boxes remotely, which are ACL'ed off to the homebase server and pulls (or pushes) the raw query results over the ssh connection. I have even touched #2 (remote syncing) as I know that would get nasty really quick. I'm interested in any ideas for a more elegant solution that can scale up and stick to my FreeBSD/Linux environment.

    Read the article

  • Can I nest a command string within another command string?

    - by Zach L
    Whenever I run the following command in an elevated command prompt, I get the 0x80070005 Access Denied error code. I'm assuming it's a permissions error for the child shell. I'm running the command in an elevated prompt on Winddows 7 Pro SP1. FORFILES /P %WINDIR%\servicing\Packages /M Microsoft-Windows-InternetExplorer-* 9.*.mum /c "cmd /c echo Uninstalling package @fname && start /w pkgmgr /up:@fname /norestart" Can place the "Runas" command within the already nested command in order to run the child shell as an admin? I don't think I can because of conflicts with quotation mark locations. If there's another way to do this, such as via a batch file, I'm open to alternative methods, although I do prefer running it as a single string. Sidenote1: Ignore the space after the first asterisk in the command string. It was added one for aesthetics & accuracy. Sub-question: Could I use this "fix" to circumnavigate the problem entirely? Prompt as Administrator? Reference for Runas #1 Reference for Runas #2

    Read the article

  • Managing SharePoint permissions via Active Directory?

    - by rgmatthes
    My company has thousands of employees organized thoroughly via Active Directory. I have confidence in the accuracy of the Department and Title information displayed in the user profiles. I'm helping to put up a brand new SharePoint 2007 site, and I contacted IT about managing the site's permissions through AD Groups. The goal is to have the site automatically assign read/write/contribute/whatever permissions based on the information in AD. For example, we could create an AD Group called "Managers" that would contain anyone with the "Manager" title in their AD user profile. I would have SharePoint tap into this AD Group to mass assign permissions if I knew all managers would need a certain level of access (read/write/contribute/whatever). Then if a manager joins the company or leaves it, the group is automatically updated (provided AD gets updated, of course). My IT rep called back and said it couldn't be done. This seems like a pretty straightforward business requirement, and one of the huge benefits of having Active Directory, but maybe I'm mistaken. Could anyone shed some light on this? A) Is it possible to use dynamically-updated AD Groups when assigning permissions via SharePoint? (Does anyone know of a guide I could show my doubtful IT rep?) B) Is there a "best practice" way to go about this? I've read some debate on whether SharePoint Groups or AD Groups are the way to go. My main concern is dynamic updating. C) If this isn't available out of the box, can someone recommend third-party software that will provide the functionality I'm looking for? A big thanks to anyone who can help me out!!

    Read the article

  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

    Read the article

  • C# performance analysis- how to count CPU cycles?

    - by Lirik
    Is this a valid way to do performance analysis? I want to get nanosecond accuracy and determine the performance of typecasting: class PerformanceTest { static double last = 0.0; static List<object> numericGenericData = new List<object>(); static List<double> numericTypedData = new List<double>(); static void Main(string[] args) { double totalWithCasting = 0.0; double totalWithoutCasting = 0.0; for (double d = 0.0; d < 1000000.0; ++d) { numericGenericData.Add(d); numericTypedData.Add(d); } Stopwatch stopwatch = new Stopwatch(); for (int i = 0; i < 10; ++i) { stopwatch.Start(); testWithTypecasting(); stopwatch.Stop(); totalWithCasting += stopwatch.ElapsedTicks; stopwatch.Start(); testWithoutTypeCasting(); stopwatch.Stop(); totalWithoutCasting += stopwatch.ElapsedTicks; } Console.WriteLine("Avg with typecasting = {0}", (totalWithCasting/10)); Console.WriteLine("Avg without typecasting = {0}", (totalWithoutCasting/10)); Console.ReadKey(); } static void testWithTypecasting() { foreach (object o in numericGenericData) { last = ((double)o*(double)o)/200; } } static void testWithoutTypeCasting() { foreach (double d in numericTypedData) { last = (d * d)/200; } } } The output is: Avg with typecasting = 468872.3 Avg without typecasting = 501157.9 I'm a little suspicious... it looks like there is nearly no impact on the performance. Is casting really that cheap?

    Read the article

  • Android: Map Overlay Labels

    - by karnage
    I am building a MapView and I want my custom overlay items to display the name of the location they are marking when the user taps them, like the Android Maps app. I setup the onTap listener and the floating TextView to hold the location name. I still need to set it up so that it redraws the label when the user moves the map, etc. Anyway, I am wondering if I am reinventing the wheel here. Is there a built-in method I am unaware of? I would think that most implementations of MapView have labels. For reference, my implementation so far: in map xml: <LinearLayout android:id="@+id/mapBubbleWrap" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true"> <TextView android:id="@+id/mapBubble" android:layout_width="wrap_content" android:layout_height="wrap_content" android:visibility="gone" android:background="#ffffff" android:textColor="#ff0000"/> </LinearLayout> in my extended ItemizedOverlay: public boolean onTap(int index) { this.setFocus( mOverlays.get(index) ); return true; } in my Activity onFocus: public void onFocusChanged( ItemizedOverlay overlay, OverlayItem item ) { if( item != null) { mapBubble.setText(item.getTitle()); Point newPoint = mapView.getProjection().toPixels(item.getPoint(), null); mapBubbleWrap.setPadding(newPoint.x, newPoint.y-10, 0, 0); mapBubble.setVisibility(View.VISIBLE); } }

    Read the article

  • Using pinvoke in c# to call sprintf and friends on 64-bit

    - by bde
    I am having an interesting problem with using pinvoke in C# to call _snwprintf. It works for integer types, but not for floating point numbers. This is on 64-bit Windows, it works fine on 32-bit. My code is below, please keep in mind that this is a contrived example to show the behavior I am seeing. class Program { [DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)] private static extern int _snwprintf([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, uint length, String format, int p); [DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)] private static extern int _snwprintf([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, uint length, String format, double p); static void Main(string[] args) { Double d = 1.0f; Int32 i = 1; Object o = (object)d; StringBuilder str = new StringBuilder(); _snwprintf(str, 32, "%10.1f", (Double)o); Console.WriteLine(str.ToString()); o = (object)i; _snwprintf(str, 32, "%10d", (Int32)o); Console.WriteLine(str.ToString()); Console.ReadKey(); } } The output of this program is 0.0 1 It should print 1.0 on the first line and not 0.0, and so far I am stumped.

    Read the article

  • How to Place DialogBar or Dialog box into pane in vc 2008 or vc 2010 Beta

    - by gbalajimecse
    Hi now i am working in 2003 vc++ and i am converting(migrating) my project in to vc 2008 or new vc 2010 Beta,i saw the feature pack of 2008,2010 regards CDockable Pane(Auto Hode,floating),so i require this features ,i want to place a dialogbox or dialog bar into pane(CDockable Pane class), so i done this in my following code Myframe Code snippet is : if (!m_MyPane.Create(L"MyPane", this, CRect(0,0,0,0), true, IDD_DIALOG1, WS_CHILD|WS_VISIBLE)) return -1; AddDockSite(); EnableDocking(CBRS_ALIGN_ANY); EnableAutoHidePanes(CBRS_ALIGN_ANY); m_MyPane.EnableDocking(CBRS_ALIGN_ANY); DockPane(&m_MyPane, AFX_IDW_DOCKBAR_RIGHT); MyPane class Definition is : include "stdafx.h" include "Pane.h" include "Resource.h" include "MainFrm.h" include "soft1.h" ifdef _DEBUG undef THIS_FILE static char THIS_FILE[]=FILE; define new DEBUG_NEW endif CPane1::CPane1() { } CPane1::~CPane1() { } BEGIN_MESSAGE_MAP(CPane1, CDockablePane) ON_WM_CREATE() ON_WM_SIZE() END_MESSAGE_MAP() int CPane1::OnCreate(LPCREATESTRUCT lpCreateStruct) { if (CDockablePane::OnCreate(lpCreateStruct) == -1) return -1; return 0; } void CPane1::OnSize(UINT nType, int cx, int cy) { CDockablePane::OnSize(nType, cx, cy); } when i build it wont shows any error and executed without error in the output the frame show the mypane but mypane didn't show IDD_DIALOG1 So is it anything am i missed please rectify my code and how to place a IDD_DIALOG1 dialogbox in to mypane PLEASE HELP ME REGARDS G.BALAJI

    Read the article

  • 2-column; multi-accordion pane

    - by Josh
    Alright, I'm having some issues and I believe it's a CSS one. Here is what I'm working on currently: http://www.notedls.com/demo/ Focusing on the News accordion menu. The idea here is to have a small image (50x50 with padding) and then a huge headline next to it. When the user clicks the headline, it expands to the article. If the user wants to read comments or make a comment themselves they can then click the View Comments to expand it even further. The issue I'm having (if it isn't clear) is the spacing with the image and the text. I could simply just increase the height of the ui.accordion-acc or -left to make everything fit, but that doesn't solve the issue. If you notice when you click on the first expansion of Headline 1, it will wrap View Comments underneath the image. This is something I don't want, I've tried separating these elements into additional divs and even floating, but its just not working. Essentially, I want blank space infinitely underneath the image for however long the article+comments may take the field.

    Read the article

  • iPhone Development - CLLocationManager vs. MapKit

    - by Mustafa
    If i want to show userLocation on the map, and at the same time record the user's location, is it a good idea to add an observer to userLocation.location and record the locations, OR should i still use CLLocationManager for recording user location and use mapView.showUserLocation to show the user's current location (blue indicator)? I want to show the default blue indicator supported by the MapKit API. Also, here's a rough sample code: - (void)viewDidLoad { ... locationManager = [[CLLocationManager alloc] init]; locationManager.desiredAccuracy = kCLLocationAccuracyBest; locationManager.distanceFilter = DISTANCE_FILTER_VALUE; locationManager.delegate = self; [locationManager startUpdatingLocation]; myMapView.showUserLocation = YES; [myMapView addObserver:self forKeyPath:@"userLocation.location" options:0 context:nil]; ... } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { // Record the location information // ... } - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { NSLog(@"%s begins.", __FUNCTION__); // Make sure that the location returned has the desired accuracy if (newLocation.horizontalAccuracy <= manager.desiredAccuracy) return; // Record the location information // ... } Under the hood, i think MKMapView also uses CLLocationManager to get user's current location? So, will this create any problems because i believe both CLLocationManager and MapView will try to use same location services? Will there be any conflicts and lack of accurate/required or current data?

    Read the article

  • C# rounding DateTime objects

    - by grenade
    I want to round dates/times to the nearest interval for a charting application. I'd like an extension method signature like follows so that the rounding can be acheived for any level of accuracy: static DateTime Round(this DateTime date, TimeSpan span); The idea is that if I pass in a timespan of ten minutes, it will round to the nearest ten minute interval. I can't get my head around the implementation and am hoping one of you will have written or used something similar before. I think either a floor, ceiling or nearest implementation is fine. Any ideas? Edit: Thanks to @tvanfosson & @ShuggyCoUk, the implementation looks like this: public static class DateExtensions { public static DateTime Round(this DateTime date, TimeSpan span) { long ticks = (date.Ticks / span.Ticks) + (span.Ticks / 2) + 1; return new DateTime(ticks * span.Ticks); } public static DateTime Floor(this DateTime date, TimeSpan span) { long ticks = (date.Ticks / span.Ticks); return new DateTime(ticks * span.Ticks); } public static DateTime Ceil(this DateTime date, TimeSpan span) { long ticks = (date.Ticks + span.Ticks - 1) / span.Ticks; return new DateTime(ticks * span.Ticks); } } And is called like so: DateTime nearestHour = DateTime.Now.Round(new TimeSpan(1,0,0)); DateTime minuteCeiling = DateTime.Now.Ceil(new TimeSpan(0,1,0)); DateTime weekFloor = DateTime.Now.Floor(new TimeSpan(7,0,0,0)); ... Cheers!

    Read the article

  • Is there a way to receive receive data as unsugned char over UDP on QT

    - by user269037
    I need to send floating point numbers using UDP connection to a QT application. Now in QT the only function available is qint64 readDatagram ( char * data, qint64 maxSize, QHostAddress * address = 0, quint16 * port = 0 ) which accepts data in the form of signed character buffer. I can convert my float into a string and send it but it will obviously not be very efficient converting a 4 byte float into a much longer sized character buffer. I got hold of these 2 functions to convert a 4 byte float into an unsinged 32 bit integer to transfer over network which works fine for a simple c++ udp program but for QT I need to receive the data as unsigned char. Is it possible to avoid converting the floatinf point data into a string and then sending it ?? uint32_t htonf(float f) { uint32_t p; uint32_t sign; if (f < 0) { sign = 1; f = -f; } else { sign = 0; } p = ((((uint32_t)f)&0x7fff)<<16) | (sign<<31); // whole part and sign p |= (uint32_t)(((f - (int)f) * 65536.0f))&0xffff; // fraction return p; } float ntohf(uint32_t p) { float f = ((p16)&0x7fff); // whole part f += (p&0xffff) / 65536.0f; // fraction if (((p>>31)&0x1) == 0x1) { f = -f; } // sign bit set return f; }

    Read the article

  • extjs - 'Store is undefined'

    - by Jamie
    Hi all, I'm pretty sure this a trivial problem and i'm just being a bit stupid. Your help would be hugely appreciated. In controls/dashboard.js I have: Ext.ill.WCSS.controls.dashboard = { xtype:'portal', region:'center', margins:'35 5 5 0', items:[{ columnWidth: 1, style:'padding:10px', items:[{ title: 'My Cluster Jobs', layout:'fit', html: "test" }] },{ columnWidth: 1, style:'padding:10px', items:[{ title: 'All Cluster Jobs', iconCls: 'icon-queue', html: "test", items: new Ext.grid.GridPanel({ title: 'Cluster Job Queue', store: Ext.ill.WCSS.stores.dashboardClusterJobs, width: 791, height: 333, frame: true, loadMask: true, stateful: false, autoHeight: true, stripeRows: true, floating: false, footer: false, collapsible: false, animCollapse: false, titleCollapse: false, columns:[ { xtype: 'gridcolumn', header: 'Job ID', sortable: true, resizable: true, width: 100, dataIndex: 'JB_job_number', fixed: false }, { xtype: 'gridcolumn', header: 'Priority', sortable: true, resizable: true, width: 100, dataIndex: 'JAT_prio', fixed: false }, { xtype: 'gridcolumn', header: 'User', sortable: true, resizable: true, width: 100, dataIndex: 'JB_owner' }, { xtype: 'gridcolumn', header: 'State', sortable: true, resizable: true, width: 100, dataIndex: 'state' }, { xtype: 'gridcolumn', header: 'Date Submitted', sortable: true, resizable: true, width: 100, dataIndex: 'JAT_start_time' }, { xtype: 'gridcolumn', header: 'Queue', sortable: true, resizable: true, width: 100, dataIndex: 'queue_name' }, { xtype: 'gridcolumn', header: 'CPUs', sortable: true, resizable: true, width: 100, dataIndex: 'slots' } ], bbar: { xtype: 'paging', store: 'storeClusterQueue', displayInfo: true, refreshText: 'Retrieving queue status...', emptyMsg: 'No jobs to retrieve', id: 'clusterQueuePaging' } }) }] }] }; Simple enough, note the reference to 'Ext.ill.WCSS.stores.dashboardClusterJobs' So in stores/dashboard.js I just have this: Ext.ill.WCSS.stores.dashboardClusterJobs = new Ext.data.XmlStore({ storeId: 'storeClusterJobs', record: 'job_list', autoLoad: true, url: 'joblist.xml', idPath: 'job_info', remoteSort: false, fields: [ { name: 'JB_job_number' }, { name: 'JAT_prio' }, { name: 'JB_name' }, { name: 'JB_owner' }, { name: 'state' }, { name: 'JAT_start_time' }, { name: 'slots' }, { name: 'queue_name' } ] }); I run the code and I get 'store is undefined' :S It's confusing me a lot. All of the javascripts have been included in the correct order. i.e. <script type="text/javascript" src="/js/portal.js"></script> <script type="text/javascript" src="/js/stores/dashboard.js"></script> <script type="text/javascript" src="/js/controls/dashboard.js"></script> Thanks guys!

    Read the article

  • highcharts correct json input

    - by Linus
    i am trying to do a basic column chart. i have looked the examples but not sure why i do not see any graph (lines). I can see the title and subtitle appear an no javascript errors in firebug. any help please $(function () { var chart; $(document).ready(function() { chart = new Highcharts.Chart({ chart: { renderTo: 'container', type: 'column', events: { load: requestData } }, title: { text: 'Some title' }, subtitle: { text: 'subtitle' }, xAxis: { categories: [], title: { text: null } }, yAxis: { min: 0, title: { text: 'y-Axis', align: 'high' } }, tooltip: { formatter: function() { return ''+ this.series.name +': '+ this.y +' '; } }, plotOptions: { bar: { dataLabels: { enabled: true } } }, legend: { layout: 'vertical', align: 'right', verticalAlign: 'top', x: -100, y: 100, floating: true, borderWidth: 1, backgroundColor: '#FFFFFF', shadow: true }, credits: { enabled: false }, series:[] }); }); function requestData() { $.ajax({ url: 'test.json', success: function(data) { options.series[0].push(data); chart.redraw(); }, cache: false }); } }); my json input file is below [ { name: 'name1', y: [32.6,16.6,1.5] }, { name: 'name2', y: [6.7,0.2,0.6] }, { name: 'name3', y: [1,3.7,0.7] }, { name: 'name4', y: [20.3,8.8,9.5] },{ name: 'name5', y: [21.5,10,7.2] }, { name: 'name6', y: [1.4,1.8,3.7] }, { name: 'name7', y: [8.1,0,0] }, { name: 'name8', y: [28.9,8.9,6.6] } ]

    Read the article

  • Find unique vertices from a 'triangle-soup'

    - by sum1stolemyname
    I am building a CAD-file converter on top of two libraries (Opencascade and DWF Toolkit). However, my question is plattform agnostic: Given: I have generated a mesh as a list of triangular faces form a model constructed through my application. Each Triangle is defined through three vertexes, which consist of three floats (x, y & z coordinate). Since the triangles form a mesh, most of the vertices are shared by more then one triangle. Goal: I need to find the list of unique vertices, and to generate an array of faces consisting of tuples of three indices in this list. What i want to do is this: //step 1: build a list of unique vertices for each triangle for each vertex in triangle if not vertex in listOfVertices Add vertex to listOfVertices //step 2: build a list of faces for each triangle for each vertex in triangle Get Vertex Index From listOfvertices AddToMap(vertex Index, triangle) While I do have an implementation which does this, step1 (the generation of the list of unique vertices) is really slow in the order of O(n!), since each vertex is compared to all vertices already in the list. I thought "Hey, lets build a hashmap of my vertices' components using std::map, that ought to speed things up!", only to find that generating a unique key from three floating point values is not a trivial task. Here, the experts of stackoverflow come into play: I need some kind of hash-function which works on 3 floats, or any other function generating a unique value from a 3d-vertex position.

    Read the article

  • Is there a more useful explanation for UITableViewStylePlain?

    - by mystify
    From the docs: In the plain style, section headers and footers float above the content if the part of a complete section is visible. A table view can have an index that appears as a bar on the right hand side of the table (for example, "a" through "z"). You can touch a particular label to jump to the target section. I find that very hard to grasp. First, this one: if the part of a complete section is visible What do they mean by this? This is paradox. Which one is it? A) Table must be exactly the height of that section. If I have 5 Rows, and each row is 50px high, I must make it 5*50 high. The full section must be visible on the screen. Otherwise, if I have 100 rows but my table view is only 400 high, this will not apply. Nothing will float above my content. Sounds wrong. B) It doesn't matter how high my table view actually is. Header and Footer is floating above the content and I can scroll the section. Makes more sense. But is completely against this nonsense making sentence: 'if the part of a complete section is visible' Can anyone explain it better than they did?

    Read the article

  • Vote on Pros and Cons of Java HTML to XML cleaners

    - by George Bailey
    I am looking to allow HTML emails (and other HTML uploads) without letting in scripts and stuff. I plan to have a white list of safe tags and attributes as well as a whitelist of CSS tags and value regexes (to prevent automatic return receipt). I asked a question: Parse a badly formatted XML document (like an HTML file) I found there are many many ways to do this. Some systems have built in sanitizers (which I don't care so much about). This page is a very nice listing page but I get kinda lost http://java-source.net/open-source/html-parsers It is very important that the parsers never throw an exception. There should always be best guess results to the parse/clean. It is also very important that the result is valid XML that can be traversed in Java. I posted some product information and said Community Wiki. Please post any other product suggestions you like and say Community Wiki so they can be voted on. Also any comments or wiki edits on what part of a certain product is better and what is not would be greatly appreciated. (for example,, speed vs accuracy..) It seems that we will go with either jsoup (seems more active and up to date) or TagSoup (compatible with JDK4 and been around awhile). A +1 for any of these products would be if they could convert all style sheets into inline style on the elements.

    Read the article

  • Forcing CLLocationManager updates - does it help or hurt?

    - by Steve N
    I've been trying to find any way to optimize the performance of my location-based iPhone application and have seen some people mention that you can force location updates by starting and stopping your CLLocationManager. I need the best accuracy I can get, and the user in my case would probably like to see updates every few seconds (say, 10 seconds) as they walk around. I've set the filters accordingly, but I notice that sometimes I don't get any updates on the device for quite some time. I'm testing the following approach, which forces an update when a fixed time interval passes (I'm using 20 seconds). My gut tells me this really won't help me provide more accurate updates to the user, and that just leaving CLLocationManager running all the time is probably the best approach. - (void)forceLocationUpdate { [[LocationManager locationManager] stopUpdates]; [[LocationManager locationManager] startUpdates]; [self performSelector:@selector(forceLocationUpdate) withObject:nil afterDelay:20.0]; } My question is- does forcing updates from CLLocationManager actually improve core location performance? Does it hurt performance? If I'm outside in an open field with good GPS reception, will this help then? Does anyone have experience trying this? Thanks in advance, Steve

    Read the article

  • iPhone UIView Animation Disables UIButton Subview

    - by bensnider
    So I've got a problem with buttons and animations. Basically, I'm animating a view using the UIView animations while also trying to listen for taps on the button inside the view. The view is just as large as the button, and the view is actually a subclass of UIImageView with an image below the button. The view is a subview of a container view placed in Interface Builder with user interaction enabled and clipping enabled. All the animation and button handling is done in this UIImageView subclass, while the startFloating message is sent from a separate class as needed. If I do no animation, the buttonTapped: message gets sent correctly, but during the animation it does not get sent. I've also tried implementing the touchesEnded method, and the same behavior occurs. UIImageView subclass init (I have the button filled with a color so I can see the frame gets set properly, which it does): - (id)initWithImage:(UIImage *)image { self = [super initWithImage:image]; if (self != nil) { // ...stuffs UIButton *tapBtn = [UIButton buttonWithType:UIButtonTypeCustom]; tapBtn.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height); [tapBtn addTarget:self action:@selector(buttonTapped:) forControlEvents:UIControlEventTouchUpInside]; tapBtn.backgroundColor = [UIColor cyanColor]; [self addSubview:tapBtn]; self.userInteractionEnabled = YES; } return self; } Animation method that starts the animation (if I don't call this the button works correctly): - (void)startFloating { [UIView beginAnimations:@"floating" context:nil]; [UIView setAnimationDelegate:self]; [UIView setAnimationCurve:UIViewAnimationCurveLinear]; [UIView setAnimationDuration:10.0f]; self.frame = CGRectMake(self.frame.origin.x, -self.frame.size.height, self.frame.size.width, self.frame.size.height); [UIView commitAnimations]; } So, to be clear: Using the UIView animation effectively disables the button. Disabling the animation causes the button to work. The button is correctly sized and positioned on screen, and moves along with the view correctly.

    Read the article

  • IE6 background-position(?) issue

    - by turezky
    I apply to stackoverflow as my last resort. I got this ie6 bug while using the image at the background of the link. It seems that ie6 scrolls the background. How can I avoid it? At some width it shows like this: And at some other it shows like that: IE7 & FF show this just like I expect: The links are placed inside the div which is floating to the right. <a href="/tr" class="menuLink" style="background-image:url(/img/tr.png);">TR</a> <a href="/eng" class="menuLink" style="background-image:url(/img/eng.png); margin-right:30px;">ENG</a> <a href="/logout" class="menuLink" style="background-image:url(/img/logout.png);"><?=$ui["exit"];?></a> .menuLink { font-family:"Tahoma"; font-size:11px; color:#003300; text-decoration:underline; font-weight: bold; background-position:0% 50%; background-repeat:no-repeat; } .menuLink:hover { font-size:11px; color:#047307; text-decoration:underline; font-weight: bold; } Any hints how can I avoid this?

    Read the article

  • Compiler optimization causing the performance to slow down

    - by aJ
    I have one strange problem. I have following piece of code: template<clss index, class policy> inline int CBase<index,policy>::func(const A& test_in, int* srcPtr ,int* dstPtr) { int width = test_in.width(); int height = test_in.height(); double d = 0.0; //here is the problem for(int y = 0; y < height; y++) { //Pointer initializations //multiplication involving y //ex: int z = someBigNumber*y + someOtherBigNumber; for(int x = 0; x < width; x++) { //multiplication involving x //ex: int z = someBigNumber*x + someOtherBigNumber; if(soemCondition) { // floating point calculations } *dstPtr++ = array[*srcPtr++]; } } } The inner loop gets executed nearly 200,000 times and the entire function takes 100 ms for completion. ( profiled using AQTimer) I found an unused variable double d = 0.0; outside the outer loop and removed the same. After this change, suddenly the method is taking 500ms for the same number of executions. ( 5 times slower). This behavior is reproducible in different machines with different processor types. (Core2, dualcore processors). I am using VC6 compiler with optimization level O2. Follwing are the other compiler options used : -MD -O2 -Z7 -GR -GX -G5 -X -GF -EHa I suspected compiler optimizations and removed the compiler optimization /O2. After that function became normal and it is taking 100ms as old code. Could anyone throw some light on this strange behavior? Why compiler optimization should slow down performance when I remove unused variable ? Note: The assembly code (before and after the change) looked same.

    Read the article

< Previous Page | 38 39 40 41 42 43 44 45 46 47 48 49  | Next Page >