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  • Starting and stopping X11 and LXDE from command line

    - by Radian
    I have a Raspberry Pi with Debian Wheezy (Raspbian) and so far I've managed to learn quite a lot about Linux just playing around, but I have a few questions for all you seasoned Linux pros out there. 1) From command line, if I execute startx, X11 will launch followed by LXDE. If I had a monitor connected, I'm imagining I would see a transition from command line to the desktop environment. Can I launch X11 first with x, then start LXDE on top of X11 afterwards with /etc/init.d/lxdm start (is this correct?) and get to the same result as startx? 2) Instead, let's say I executed /etc/init.d/lxdm start alone, would X11 start automatically (since LXDE relies on X11)? 3) From desktop, if I CTRL+ALT+F1 to get back to command line, then I should be able to shutdown LXDE using /etc/init.d/lxdm stop. Does X11 automatically close with the termination of LXDE? 4) What is the proper/safe way to shutdown X11? Thanks

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  • Streaming media from linux server - low footprint is crucial

    - by Mike Haye
    I recently pre-ordered the Raspberry Pi. http://www.raspberrypi.org/faqs For those of you who don't know it, it's a machine with 256 mb ram and a 700 MHz processor for $35. I plan to run linux on an SD card on this machine and have it act as both a htpc, VPN and media server. In regard to the media server part, I need to find some linux software that has a small footprint, but allows me to stream media to other devices connected to the internet (preferably without having to install any additional software on the client machines) Also, I would love if the video could be compressed, so the data usage wouldn't be so big for the client machine (e.g. when I'm using my data plan on my smartphone ;) ) Thanks in advance for any answers :) Mike.

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  • can I display a JPG or PNG to the framebuffer (/dev/fb*)?

    - by ndmweb
    I know I can capture the framebuffer in linux using something like cp /dev/fb0 ~/myimage and re-display that by coping back to the device like so cp ~/myimage /dev/fb0. What format is the framebuffer image data in? and how would I go about displaying a pre-made image (jpg, png) to the framebuffer? Can I convert to this format using imagemagick? p.s. Im using a raspberry pi running raspbian. Update 11-12-2012 I ended up using pygame to display images in my application. Not sure if this uses the frame-buffer to display the images. But it meets my needs quite well.

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  • Wired to wireless bridge in Linux

    - by adrianmcmenamin
    I am attempting to set up my Raspberry Pi as a bridge (but I think this is not a question specific to the hardware) - using Debian wheezy. I have a hostapd.conf: (some details changed for security)... interface=wlan0 bridge=br0 driver=nl80211 auth_algs=1 macaddr_acl=0 ignore_broadcast_ssid=0 logger_syslog=-1 logger_syslog_level=0 hw_mode=g ssid=MY_SSID channel=11 wep_default_key=0 wep_key0=MY_KEY wpa=0 (yes, I know WEP is no good) And this in /etc/network/interfaces auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface default inet dhcp auto br0 iface br0 inet dhcp bridge-ports eth0 wlan0 Everything seems to come up ok, but I cannot associate with the bridged wireless connection - even though the flashing lights on the USB stick suggest packets are being exchanged. I have read somewhere that not all cards/devices will run in hostap mode - they won't pass packets in one direction: is that right? (The info was a bit old)- this my card: [ 3.663245] usb 1-1.3.1: new high-speed USB device number 5 using dwc_otg [ 3.794187] usb 1-1.3.1: New USB device found, idVendor=0cf3, idProduct=9271 [ 3.804321] usb 1-1.3.1: New USB device strings: Mfr=16, Product=32, SerialNumber=48 [ 3.816994] usb 1-1.3.1: Product: USB2.0 WLAN [ 3.823790] usb 1-1.3.1: Manufacturer: ATHEROS [ 3.830645] usb 1-1.3.1: SerialNumber: 12345 So, what have I got wrong here?

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  • How to set up Node server for production on own machine?

    - by Matt Hintzke
    This must be a pretty basic thing to do, but I cannot find any good guide on how to do it on the internet. I only find how to set up a development environment for Node. I want to be able to forward my R-Pi's port 80 to my Node server, which I want to obviously listen on port 80. How can I close the native port 80 so that I can let me Node server listen on that port. Ultimately, I want to be able to access my pi from any remote location. I know how to set up a static IP and forward the port on my router, but now how do I allow Node into port 80?

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  • How long would this have to go on for...

    - by Pieman
    I have the Pi formulae -Well one of them... 1 - 1/3 + 1/5 - 1/7 etc. How long would it take to get to like 1000 S.F correct? -Well, not how long, how big would the denominator be? -I have it updating 4 times in one refresh: http://zombiewrath.com/pi.php So the section above would be done in one refresh, then 7 to 13 in another etc. Answer this maths question please :) Also how can I get the 10,002 length variable onto 'seperate lines'? -I want it to fill 100% screen width -no scrolling needed (well downwards only)

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  • 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!

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  • Undefined reference to 'glib'

    - by dali1985
    I would like to parse a config file using glib in Codeblocks which I use. So I want to do exactly the example which is described here first. I have a file named myconfig.cfg and and a code programming.c. I just copy and paste the code to see if glib works but unfortunately it does not work. I did the installation of glib2.0 using sudo apt-get, I found where are the libs in glibs using pkg-config --cflags --libs glib-2.0 and in this path project->Build Options->Compiler Settings-> Other Options I added -I/usr/include/glib-2.0 -I/usr/lib/arm-linuxgnuebihf/glib-2.0/include When I build and run the programming.c I have these errors -------------- Build: Debug in programming --------------- gcc -Wall -g -I/usr/include/glib-2.0 -I/usr/lib/arm-linux-gnueabihf/glib-2.0/include -std=c99 -c /home/pi/Desktop/programming/main.c -o obj/Debug/main.o g++ -o bin/Debug/programming obj/Debug/main.o /usr/lib/libmysqlclient.so.16 obj/Debug/main.o: In function `main': /home/pi/Desktop/programming/main.c:22: undefined reference to `g_key_file_new' /home/pi/Desktop/programming/main.c:26: undefined reference to `g_key_file_load_from_file' /home/pi/Desktop/programming/main.c:28: undefined reference to `g_log' /home/pi/Desktop/programming/main.c:34: undefined reference to `g_slice_alloc' /home/pi/Desktop/programming/main.c:37: undefined reference to `g_key_file_get_string' /home/pi/Desktop/programming/main.c:39: undefined reference to `g_key_file_get_locale_string' /home/pi/Desktop/programming/main.c:41: undefined reference to `g_key_file_get_boolean_list' /home/pi/Desktop/programming/main.c:43: undefined reference to `g_key_file_get_integer_list' /home/pi/Desktop/programming/main.c:45: undefined reference to `g_key_file_get_string_list' /home/pi/Desktop/programming/main.c:47: undefined reference to `g_key_file_get_integer' /home/pi/Desktop/programming/main.c:49: undefined reference to `g_key_file_get_double_list' collect2: ld returned 1 exit status Process terminated with status 1 (0 minutes, 6 seconds) 11 errors, 0 warnings Am I missing something? I tried also to do in the same way with libconfig but again I have undefined reference. Is the problem the path?

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  • Mathematica Programming Language&ndash;An Introduction

    - by JoshReuben
    The Mathematica http://www.wolfram.com/mathematica/ programming model consists of a kernel computation engine (or grid of such engines) and a front-end of notebook instances that communicate with the kernel throughout a session. The programming model of Mathematica is incredibly rich & powerful – besides numeric calculations, it supports symbols (eg Pi, I, E) and control flow logic.   obviously I could use this as a simple calculator: 5 * 10 --> 50 but this language is much more than that!   for example, I could use control flow logic & setup a simple infinite loop: x=1; While [x>0, x=x,x+1] Different brackets have different purposes: square brackets for function arguments:  Cos[x] round brackets for grouping: (1+2)*3 curly brackets for lists: {1,2,3,4} The power of Mathematica (as opposed to say Matlab) is that it gives exact symbolic answers instead of a rounded numeric approximation (unless you request it):   Mathematica lets you define scoped variables (symbols): a=1; b=2; c=a+b --> 5 these variables can contain symbolic values – you can think of these as partially computed functions:   use Clear[x] or Remove[x] to zero or dereference a variable.   To compute a numerical approximation to n significant digits (default n=6), use N[x,n] or the //N prefix: Pi //N -->3.14159 N[Pi,50] --> 3.1415926535897932384626433832795028841971693993751 The kernel uses % to reference the lastcalculation result, %% the 2nd last, %%% the 3rd last etc –> clearer statements: eg instead of: Sqrt[Pi+Sqrt[Sqrt[Pi+Sqrt[Pi]]] do: Sqrt[Pi]; Sqrt[Pi+%]; Sqrt[Pi+%] The help system supports wildcards, so I can search for functions like so: ?Inv* Mathematica supports some very powerful programming constructs and a rich function library that allow you to do things that you would have to write allot of code for in a language like C++.   the Factor function – factorization: Factor[x^3 – 6*x^2 +11x – 6] --> (-3+x) (-2+x) (-1+x)   the Solve function – find the roots of an equation: Solve[x^3 – 2x + 1 == 0] -->   the Expand function – express (1+x)^10 in polynomial form: Expand[(1+x)^10] --> 1+10x+45x^2+120x^3+210x^4+252x^5+210x^6+120x^7+45x^8+10x^9+x^10 the Prime function – what is the 1000th prime? Prime[1000] -->7919 Mathematica also has some powerful graphics capabilities:   the Plot function – plot the graph of y=Sin x in a single period: Plot[Sin[x], {x,0,2*Pi}] you can also plot 3D surfaces of functions using Plot3D function

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  • Required Working Precision for the BBP Algorithm?

    - by brainfsck
    Hello, I'm looking to compute the nth digit of Pi in a low-memory environment. As I don't have decimals available to me, this integer-only BBP algorithm in Python has been a great starting point. I only need to calculate one digit of Pi at a time. How can I determine the lowest I can set D, the "number of digits of working precision"? D=4 gives me many correct digits, but a few digits will be off by one. For example, computing digit 393 with precision of 4 gives me 0xafda, from which I extract the digit 0xa. However, the correct digit is 0xb. No matter how high I set D, it seems that testing a sufficient number of digits finds an one where the formula returns an incorrect value. I've tried upping the precision when the digit is "close" to another, e.g. 0x3fff or 0x1000, but cannot find any good definition of "close"; for instance, calculating at digit 9798 gives me 0xcde6 , which is not very close to 0xd000, but the correct digit is 0xd. Can anyone help me figure out how much working precision is needed to calculate a given digit using this algorithm? Thank you,

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  • Use Math class to calculate

    - by LC
    Write a JAVA program that calculates the surface area of a cylinder, C= 2( p r2) + 2 p r h, where r is the radius and h is the height of the cylinder. Allow the user to enter in a radius and a height. Format the output to three decimal places. Use the constant PI and the method pow() from the Math class. This is what I've done so far but it can not run. Can anyone help me ? import Java.util Scanner; public class Ex5 { public static void main (String[] args) { Scanner input.new Scanner(System.in); double radius,height,area; System.out.print("Please enter the radius of the Cylinder"); radius = input.nextDouble(); System.out.print("Please enter the height of the Cylinder"); height = input.nextDouble(); area = (4*Math.PI*radius)+2*Math.PIMath.POW(radius,2); System.out.println("The surface of the cylinder" + area); } }

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  • From the Tips Box: Kindle as Raspberry Pi Screen, iPod Control Boxes, and Easy Six Degrees of Kevin Bacon

    - by Jason Fitzpatrick
    Once a week we round up some of the great reader tips that come our way and share them with everyone. Today we’re looking at using the Kindle as a screen for the Raspberry Pi, custom iPod control modules, and an easy way to play the Six Degrees of Kevin Bacon. How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using? HTG Explains: What The Windows Event Viewer Is and How You Can Use It

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  • Can only ssh when not using wifi

    - by AChrapko
    So I have 3 machines, a windows 7 desktop that is always wired to my router, osX laptop, and raspberry pi running debian linux. My router is a Linksys e1000 wireless N. My goal is to be able to ssh the raspi from any machine, while it is connected via wifi. My problem is that when trying to ssh from either the win7 or osX to the Pi it either times out, or gives an error: "ssh: connect to host 192.168.1.### port 22: No route to host" The only times that I have managed to connect to the pi from any machine were when it connected to the router via an Ethernet cable. Currently with win7 desktop wired, macbook wireless, and pi wireless tests give the following: win7 ping macbook: Destination host unreachable. macbook ping win7: Request timeout. win7 ping pi: Destination host unreachable. macbook ping pi: Request timeout. blah blah blah Plugging the macbook into the router with an Ethernet cable all communication between win7 and macbook works. Pings, ssh, ftp, smb ect... No changes to the pi, still no connections possible to or from any of the other 2 machines. Note All machines, are able to connect to the internet and ssh to the same machine on a completely different network, wired or over wifi. Plugging the Pi in with Ethernet (and macbook still wired) I can ssh to the pi from both win7 and macbook. I can ssh from the pi to macbook. All machines still able to connect the the off network machine. Also another little side note- I was playing warcraft 3 with my roommates the other day, and the only time they were able to see my LAN game was when they were plugged into the router with an Ethernet cable. Once or twice one of the laptops was able to connect over wifi, but not without another computer connecting first via Ethernet. So basically does anyone have any info as to why my router seems to completely ignore local wireless traffic?

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  • how to exit recursive math formula and still get an answer

    - by calccrypto
    i wrote this python code, which from wolfram alpha says that its supposed to return the factorial of any positive value (i probably messed up somewhere), integer or not: from math import * def double_factorial(n): if int(n) == n: n = int(n) if [0,1].__contains__(n): return 1 a = (n&1) + 2 b = 1 while a<=n: b*=a a+= 2 return float(b) else: return factorials(n/2) * 2**(n/2) *(pi/2)**(.25 *(-1+cos(n * pi))) def factorials(n): return pi**(.5 * sin(n*pi)**2) * 2**(-n + .25 * (-1 + cos(2*n*pi))) * double_factorial(2*n) the problem is , say i input pi to 6 decimal places. 2*n will not become a float with 0 as its decimals any time soon, so the equation turns out to be pi**(.5 * sin(n*pi)**2) * 2**(-n + .25 * (-1 + cos(2*n*pi))) * double_factorial(loop(loop(loop(...))))) how would i stop the recursion and still get the answer? ive had suggestions to add an index to the definitions or something, but the problem is, if the code stops when it reaches an index, there is still no answer to put back into the previous "nests" or whatever you call them

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  • how do i design a high pass filters in matlab without using the builtin function?

    - by noura
    hello everyone, i'm just not sure how to draw the frequency response (H) of the high pass filter? after drawing the frequency response i can get the b coefficient by taking the ifft of (H). so yeah, for a low pass filter, with a cutoff frequency of say pi/2 : the frequency response code will be H = exp(-1*j*w*4).*(((0 <= w) & (w<= pi/2)) | ((2*pi - pi/2 <= w) & (w<=2*pi)); sincr the response is "1" between 0 and pi/2 and between (2*pi - pi/2) and 2*pi. can you help me write H for a high pass filter? thanx in advance.

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  • How to permanently add wireless interfaces with iw

    - by walli
    How can I permanently add virtual wireless interfaces to my network configuration with iw? I created the following interfaces: iw phy phy0 interface add vwlan0 type station iw phy phy0 interface add vwlan1 type __ap The first is configured as a wifi client connecting to an existing network (wpa_supplicant) The second is configured as wireless hotspot (hostapd + dnsmasq) The setup works, but now I can't quite figure out what the best strategy is to save this configuration permanently. Have made an init script for wpa_supplicant Have made an init script for the hotspot Virtual adaptor network settings set in /etc/network/interfaces But all this depends on the wireless interfaces being created. What would be the best way to make sure these interfaces are created before the network is set up and the services are run? As a bonus, since this wireless interface is a usb device, would it be possible to have the interfaces created (and the services started) when the interface is hotplugged? I know you can execute code after a network interface is up, but the wlan0 interface that is hotplugged should never be up. Operating system is raspbian

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  • Can't ping through default gateway

    - by Andrew G.H.
    I have the following configuration: Routing table on M3 is: Destination Gateway Genmask Flags MSS Window irtt Iface 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 192.168.3.0 0.0.0.0 255.255.255.192 U 0 0 0 eth0 Routing table on M1 is: Destination Gateway Genmask Flags MSS Window irtt Iface 0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 So basically M3's gateway is M1, and M1's gateway is M2's wireless internet interface. If I ping 8.8.8.8 from M1, everything is ok, replies are received. Pinging from M1 to M3 and viceversa is also possible. I have configured M1 as gateway trafic forwarder using firestarter package and stopped firewall with it. iptables policies are ACCEPT for everything. Problem: I have tried ping-ing ip 8.8.8.8 from M3 but without success. What could be the source of this problem?

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  • Bootable SD card still has small memory, even after formating

    - by Inazuma
    I have an SD card which I used to run my RaspberryPi. I wanted to update the copy of raspbian on it, so I formated the card using the software from www.sdcard.com. I followed all the instructions correctly, however the size of my SD card didn't go back to it's default. It is a 4gb SD card, which after it's spell in the RaspberryPi had shrunken to 52mb, which I understand is normal. After formatting, the size rose to 3.69gb. This means that there is not enough space to install a new OS, so how can I make my SD card 4gb again? Any help would be much appreciated!

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  • How can I access my mini-pc (RaspberryPi / MK802 / Mele A1000 / VIA APC) via ethernet/wifi without having Monitor?

    - by sky770
    Soon I will be getting my own mini-PC (RaspberryPi / MK802 / Mele A1000 / VIA APC). But I was wondering whether is there any possibility that I can just power up and access my mini-pc's OS by connecting it to wifi/ethernet link and remotely access it over the LAN without actually needing a monitor (throughout the process?) ? I currently own a laptop and need a download box and later will be getting a HDTV for converting to a HTPC :D So, I don't really own a spare monitor now but I do have an extra keyboard and mouse. Is there exists any linux distro for the same? which I can use to directly fireup my mini-pc and hook it up across my LAN to remotely access through my laptop? Any suggestions appreciated :) Regards, sky770

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  • Web Platform Installer bundles for Visual Studio 2010 SP1 - and how you can build your own WebPI bundles

    - by Jon Galloway
    Visual Studio SP1 is  now available via the Web Platform Installer, which means you've got three options: Download the 1.5 GB ISO image Run the 750KB Web Installer (which figures out what you need to download) Install via Web PI Note: I covered some tips for installing VS2010 SP1 last week - including some that apply to all of these, such as removing options you don't use prior to installing the service pack to decrease the installation time and download size. Two Visual Studio 2010 SP1 Web PI packages There are actually two WebPI packages for VS2010 SP1. There's the standard Visual Studio 2010 SP1 package [Web PI link], which includes (quoting ScottGu's post): VS2010 2010 SP1 ASP.NET MVC 3 (runtime + tools support) IIS 7.5 Express SQL Server Compact Edition 4.0 (runtime + tools support) Web Deployment 2.0 The notes on that package sum it up pretty well: Looking for the latest everything? Look no further. This will get you Visual Studio 2010 Service Pack 1 and the RTM releases of ASP.NET MVC 3, IIS 7.5 Express, SQL Server Compact 4.0 with tooling, and Web Deploy 2.0. It's the value meal of Microsoft products. Tell your friends! Note: This bundle includes the Visual Studio 2010 SP1 web installer, which will dynamically determine the appropriate service pack components to download and install. This is typically in the range of 200-500 MB and will take 30-60 minutes to install, depending on your machine configuration. There is also a Visual Studio 2010 SP1 Core package [Web PI link], which only includes only the SP without any of the other goodies (MVC3, IIS Express, etc.). If you're doing any web development, I'd highly recommend the main pack since it the other installs are small, simple installs, but if you're working in another space, you might want the core package. Installing via the Web Platform Installer I generally like to go with the Web PI when possible since it simplifies most software installations due to things like: Smart dependency management - installing apps or tools which have software dependencies will automatically figure out which dependencies you don't have and add them to the list (which you can review before install) Simultaneous download and install - if your install includes more than one package, it will automatically pull the dependencies first and begin installing them while downloading the others Lists the latest downloads - no need to search around, as they're all listed based on a live feed Includes open source applications - a lot of popular open source applications are included as well as Microsoft software and tools No worries about reinstallation - WebPI installations detect what you've got installed, so for instance if you've got MVC 3 installed you don't need to worry about the VS2010 SP1 package install messing anything up In addition to the links I included above, you can install the WebPI from http://www.microsoft.com/web/downloads/platform.aspx, and if you have Web PI installed you can just tap the Windows key and type "Web Platform" to bring it up in the Start search list. You'll see Visual Studio SP1 listed in the spotlight list as shown below. That's the standard package, which includes MVC 3 / IIS 7.5 Express / SQL Compact / Web Deploy. If you just want the core install, you can use the search box in the upper right corner, typing in "Visual Studio SP1" as shown. Core Install: Use Web PI or the Visual Studio Web Installer? I think the big advantage of using Web PI to install VS 2010 SP1 is that it includes the other new bits. If you're going to install the SP1 core, I don't think there's as much advantage to using Web PI, as the Web PI Core install just downloads the Visual Studio Web Installer anyways. I think Web PI makes it a little easier to find the download, but not a lot. The Visual Studio Web Installer checks dependencies, so there's no big advantage there. If you do happen to hit any problems installing Visual Studio SP1 via Web PI, I'd recommend running the Visual Studio Web Installer, then running the Web PI VS 2010 SP1 package to get all the other goodies. I talked to one person who hit some random snag, recommended that, and it worked out. Custom Web Platform Installer bundles You can create links that will launch the Web Platform Installer with a custom list of tools. You can see an example of this by clicking through on the install button at http://asp.net/downloads (cancelling the installation dialog). You'll see this in the address bar: http://www.microsoft.com/web/gallery/install.aspx?appsxml=&appid=MVC3;ASPNET;NETFramework4;SQLExpress;VWD Notice that the appid querystring parameter includes a semicolon delimited list, and you can make your own custom Web PI links with your own desired app list. I can think of a lot of cases where that would be handy: linking to a recommended software configuration from a software project or product, setting up a recommended / documented / supported install list for a software development team or IT shop, etc. For instance, here's a link that installs just VS2010 SP1 Core and the SQL CE tools: http://www.microsoft.com/web/gallery/install.aspx?appsxml=&appid=VS2010SP1Core;SQLCETools Note: If you've already got all or some of the products installed, the display will reflect that. On my dev box which has the full SP1 package, here's what the above link gives me: Here's another example - on a fresh box I created a link to install MVC 3 and the Web Farm Framework (http://www.microsoft.com/web/gallery/install.aspx?appsxml=&appid=MVC3;WebFarmFramework) and got the following items added to the cart: But where do I get the App ID's? Aha, that's the trick. You can link to a list of cool packages, but you need to know the App ID's to link to them. To figure that out, I turned on tracing in Web Platform Installer  (also handy if you're ever having trouble with a WebPI install) and from the trace logs saw that the list of packages is pulled from an XML file: DownloadManager Information: 0 : Loading product xml from: https://go.microsoft.com/?linkid=9763242 DownloadManager Verbose: 0 : Connecting to https://go.microsoft.com/?linkid=9763242 with (partial) headers: Referer: wpi://2.1.0.0/Microsoft Windows NT 6.1.7601 Service Pack 1 If-Modified-Since: Wed, 09 Mar 2011 14:15:27 GMT User-Agent:Platform-Installer/3.0.3.0(Microsoft Windows NT 6.1.7601 Service Pack 1) DownloadManager Information: 0 : https://go.microsoft.com/?linkid=9763242 responded with 302 DownloadManager Information: 0 : Response headers: HTTP/1.1 302 Found Cache-Control: private Content-Length: 175 Content-Type: text/html; charset=utf-8 Expires: Wed, 09 Mar 2011 22:52:28 GMT Location: https://www.microsoft.com/web/webpi/3.0/webproductlist.xml Server: Microsoft-IIS/7.5 X-AspNet-Version: 2.0.50727 X-Powered-By: ASP.NET Date: Wed, 09 Mar 2011 22:53:27 GMT Browsing to https://www.microsoft.com/web/webpi/3.0/webproductlist.xml shows the full list. You can search through that in your browser / text editor if you'd like, open it in Excel as an XML table, etc. Here's a list of the App ID's as of today: SMO SMO32 PHP52ForIISExpress PHP53ForIISExpress StaticContent DefaultDocument DirectoryBrowse HTTPErrors HTTPRedirection ASPNET NETExtensibility ASP CGI ISAPIExtensions ISAPIFilters ServerSideIncludes HTTPLogging LoggingTools RequestMonitor Tracing CustomLogging ODBCLogging BasicAuthentication WindowsAuthentication DigestAuthentication ClientCertificateMappingAuthentication IISClientCertificateMappingAuthentication URLAuthorization RequestFiltering IPSecurity StaticContentCompression DynamicContentCompression IISManagementConsole IISManagementScriptsAndTools ManagementService MetabaseAndIIS6Compatibility WASProcessModel WASNetFxEnvironment WASConfigurationAPI IIS6WPICompatibility IIS6ScriptingTools IIS6ManagementConsole LegacyFTPServer FTPServer WebDAV LegacyFTPManagementConsole FTPExtensibility AdminPack AdvancedLogging WebFarmFrameworkNonLoc ExternalCacheNonLoc WebFarmFramework WebFarmFrameworkv2 WebFarmFrameworkv2_beta ExternalCache ECacheUpdate ARRv1 ARRv2Beta1 ARRv2Beta2 ARRv2RC ARRv2NonLoc ARRv2 ARRv2Update MVC MVCBeta MVCRC1 MVCRC2 DBManager DbManagerUpdate DynamicIPRestrictions DynamicIPRestrictionsUpdate DynamicIPRestrictionsLegacy DynamicIPRestrictionsBeta2 FTPOOB IISPowershellSnapin RemoteManager SEOToolkit VS2008RTM MySQL SQLDriverPHP52IIS SQLDriverPHP53IIS SQLDriverPHP52IISExpress SQLDriverPHP53IISExpress SQLExpress SQLManagementStudio SQLExpressAdv SQLExpressTools UrlRewrite UrlRewrite2 UrlRewrite2NonLoc UrlRewrite2RC UrlRewrite2Beta UrlRewrite10 UrlScan MVC3Installer MVC3 MVC3LocInstaller MVC3Loc MVC2 VWD VWD2010SP1Pack NETFramework4 WebMatrix WebMatrix_v1Refresh IISExpress IISExpress_v1 IIS7 AspWebPagesVS AspWebPagesVS_1_0 Plan9 Plan9Loc WebMatrix_WHP SQLCE SQLCETools SQLCEVSTools SQLCEVSTools_4_0 SQLCEVSToolsInstaller_4_0 SQLCEVSToolsInstallerNew_4_0 SQLCEVSToolsInstallerRepair_EN_4_0 SQLCEVSToolsInstallerRepair_JA_4_0 SQLCEVSToolsInstallerRepair_FR_4_0 SQLCEVSToolsInstallerRepair_DE_4_0 SQLCEVSToolsInstallerRepair_ES_4_0 SQLCEVSToolsInstallerRepair_IT_4_0 SQLCEVSToolsInstallerRepair_RU_4_0 SQLCEVSToolsInstallerRepair_KO_4_0 SQLCEVSToolsInstallerRepair_ZH_CN_4_0 SQLCEVSToolsInstallerRepair_ZH_TW_4_0 VWD2008 WebDAVOOB WDeploy WDeploy_v2 WDeployNoSMO WDeploy11 WinCache52 WinCache53 NETFramework35 WindowsImagingComponent VC9Redist NETFramework20SP2 WindowsInstaller31 PowerShell PowerShellMsu PowerShell2 WindowsInstaller45 FastCGIUpdate FastCGIBackport FastCGIIIS6 IIS51 IIS60 SQLNativeClient SQLNativeClient2008 SQLNativeClient2005 SQLCLRTypes SQLCLRTypes32 SMO_10_1 MySQLConnector PHP52 PHP53 PHPManager VSVWD2010Feature VWD2010WebFeature_0 VWD2010WebFeature_1 VWD2010WebFeature_2 VS2010SP1Prerequisite RIAServicesToolkitMay2010 Silverlight4Toolkit Silverlight4Tools VSLS SSMAMySQL WebsitePanel VS2010SP1Core VS2010SP1Installer VS2010SP1Pack MissingVWDOrVSVWD2010Feature VB2010Beta2Express VCS2010Beta2Express VC2010Beta2Express RIAServicesToolkitApr2010 VS2010Beta1 VS2010RC VS2010Beta2 VS2010Beta2Express VS2k8RTM VSCPP2k8RTM VSVB2k8RTM VSCS2k8RTM VSVWDFeature LegacyWinCache SQLExpress2005 SSMS2005

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  • Normal pointer vs Auto pointer (std::auto_ptr)

    - by AKN
    Code snippet (normal pointer) int *pi = new int; int i = 90; pi = &i; int k = *pi + 10; cout<<k<<endl; delete pi; [Output: 100] Code snippet (auto pointer) Case 1: std::auto_ptr<int> pi(new int); int i = 90; pi = &i; int k = *pi + 10; //Throws unhandled exception error at this point while debugging. cout<<k<<endl; //delete pi; (It deletes by itself when goes out of scope. So explicit 'delete' call not required) Case 2: std::auto_ptr<int> pi(new int); int i = 90; *pi = 90; int k = *pi + 10; cout<<k<<endl; [Output: 100] Can someone please tell why it failed to work for case 1?

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  • Ragdoll continuous movement

    - by Siddharth
    I have created a ragdoll for my game but the problem I found was that the ragdoll joints are not perfectly implemented so they are continuously moving. Ragdoll does not stand at fix place. I here paste my work for that and suggest some guidance about that so that it can stand on fix place. chest = new Chest(pX, pY, gameObject.getmChestTextureRegion(), gameObject); head = new Head(pX, pY - 16, gameObject.getmHeadTextureRegion(), gameObject); leftHand = new Hand(pX - 6, pY + 6, gameObject.getmHandTextureRegion() .clone(), gameObject); rightHand = new Hand(pX + 12, pY + 6, gameObject .getmHandTextureRegion().clone(), gameObject); rightHand.setFlippedHorizontal(true); leftLeg = new Leg(pX, pY + 18, gameObject.getmLegTextureRegion() .clone(), gameObject); rightLeg = new Leg(pX + 7, pY + 18, gameObject.getmLegTextureRegion() .clone(), gameObject); rightLeg.setFlippedHorizontal(true); gameObject.getmScene().registerTouchArea(chest); gameObject.getmScene().attachChild(chest); gameObject.getmScene().registerTouchArea(head); gameObject.getmScene().attachChild(head); gameObject.getmScene().registerTouchArea(leftHand); gameObject.getmScene().attachChild(leftHand); gameObject.getmScene().registerTouchArea(rightHand); gameObject.getmScene().attachChild(rightHand); gameObject.getmScene().registerTouchArea(leftLeg); gameObject.getmScene().attachChild(leftLeg); gameObject.getmScene().registerTouchArea(rightLeg); gameObject.getmScene().attachChild(rightLeg); // head revolute joint revoluteJointDef = new RevoluteJointDef(); revoluteJointDef.enableLimit = true; revoluteJointDef.initialize(head.getHeadBody(), chest.getChestBody(), chest.getChestBody().getWorldCenter()); revoluteJointDef.localAnchorA.set(0f, 0f); revoluteJointDef.localAnchorB.set(0f, -0.5f); revoluteJointDef.lowerAngle = (float) (0f / (180 / Math.PI)); revoluteJointDef.upperAngle = (float) (0f / (180 / Math.PI)); headRevoluteJoint = (RevoluteJoint) gameObject.getmPhysicsWorld() .createJoint(revoluteJointDef); // // left leg revolute joint revoluteJointDef.initialize(leftLeg.getLegBody(), chest.getChestBody(), chest.getChestBody().getWorldCenter()); revoluteJointDef.localAnchorA.set(0f, 0f); revoluteJointDef.localAnchorB.set(-0.15f, 0.75f); revoluteJointDef.lowerAngle = (float) (0f / (180 / Math.PI)); revoluteJointDef.upperAngle = (float) (0f / (180 / Math.PI)); leftLegRevoluteJoint = (RevoluteJoint) gameObject.getmPhysicsWorld() .createJoint(revoluteJointDef); // right leg revolute joint revoluteJointDef.initialize(rightLeg.getLegBody(), chest.getChestBody(), chest.getChestBody().getWorldCenter()); revoluteJointDef.localAnchorA.set(0f, 0f); revoluteJointDef.localAnchorB.set(0.15f, 0.75f); revoluteJointDef.lowerAngle = (float) (0f / (180 / Math.PI)); revoluteJointDef.upperAngle = (float) (0f / (180 / Math.PI)); rightLegRevoluteJoint = (RevoluteJoint) gameObject.getmPhysicsWorld() .createJoint(revoluteJointDef); // left hand revolute joint revoluteJointDef.initialize(leftHand.getHandBody(), chest.getChestBody(), chest.getChestBody().getWorldCenter()); revoluteJointDef.localAnchorA.set(0f, 0f); revoluteJointDef.localAnchorB.set(-0.25f, 0.1f); revoluteJointDef.lowerAngle = (float) (0f / (180 / Math.PI)); revoluteJointDef.upperAngle = (float) (0f / (180 / Math.PI)); leftHandRevoluteJoint = (RevoluteJoint) gameObject.getmPhysicsWorld() .createJoint(revoluteJointDef); // right hand revolute joint revoluteJointDef.initialize(rightHand.getHandBody(), chest.getChestBody(), chest.getChestBody().getWorldCenter()); revoluteJointDef.localAnchorA.set(0f, 0f); revoluteJointDef.localAnchorB.set(0.25f, 0.1f); revoluteJointDef.lowerAngle = (float) (0f / (180 / Math.PI)); revoluteJointDef.upperAngle = (float) (0f / (180 / Math.PI)); rightHandRevoluteJoint = (RevoluteJoint) gameObject.getmPhysicsWorld() .createJoint(revoluteJointDef);

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  • Segmentation fault in my C program

    - by user233542
    I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000 Here is the full code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define w 10 /*characteristic width of a soliton*/ #define dx 0.05 /*distance between lattice sites*/ #define s (2*w)/dx /*size of soliton shape*/ #define l (int)(s+1) /*array length for soliton*/ #define N (int)2000 /*length of field array--lattice sites*/ #define Pi (double)4*atan(1) #define buff (int)50 double shoot(double Sol[N],double A,double c); double bisect(double A0,double A1,double Sol[N],double tol,double c); void super_pos(double antiSol[N],double Sol[N],double phi[][N]); void vel_ver(double phi[][N],double v,double c,int tsteps,double dt); int main(int argc, char **argv) { double c,Sol[N],antiSol[N],A,A0,A1,tol,v,dt; int tsteps,i; FILE *fp1,*fp2,*fp3; fp1 = fopen("soliton.dat","w"); fp2 = fopen("final-phi.dat","w"); fp3 = fopen("energy.dat","w"); printf("Please input the number of time steps:"); scanf("%d",&tsteps); printf("Also, enter the time step size:"); scanf("%lf",&dt); do{ printf("Please input the parameter c in the interval [-1/3,1]:"); scanf("%lf",&c);} while(c < (-1./3.) || c > 1.); printf("Please input the inital speed of eiter soliton:"); scanf("%lf",&v); double phi[tsteps+1][N]; tol = 0.0000001; A0 = 0.; A1 = 2.*Pi; A = bisect(A0,A1,Sol,tol,c); shoot(Sol,A,c); for (i=0;i<N;i++) { fprintf(fp1,"%d\t",i); fprintf(fp1,"%lf\n",Sol[i]); } fclose(fp1); super_pos(antiSol,Sol,phi); /*vel_ver(phi,v,c,tsteps,dt); for (i=0;i<N;i++){ fprintf(fp2,"%d\t",i); fprintf(fp2,"%lf\n",phi[tsteps][i]); }*/ } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } void super_pos(double antiSol[N],double Sol[N],double phi[][N]) { int i; /*for (i=0;i<N;i++) { phi[i]=0; } for (i=buffer+s;i<1950-s;i++) { phi[i]=2*Pi; }*/ for (i=0;i<N;i++) { antiSol[i] = Sol[N-i]; } /*for (i=0;i<s+1;i++) { phi[buffer+j] = Sol[j]; phi[1549+j] = antiSol[j]; }*/ for (i=0;i<N;i++) { phi[0][i] = antiSol[i] + Sol[i] - 2.*Pi; } } /* This funciton will set the 2nd input array to the derivative at the time t, for all points x in the lattice */ void deriv2(double phi[][N],double DphiDx2[][N],int t) { //double SolDer2[s+1]; int x; for (x=0;x<N;x++) { DphiDx2[t][x] = (phi[buff+x+1][t] + phi[buff+x-1][t] - 2.*phi[x][t])/(dx*dx); } /*for (i=0;i<N;i++) { ptr[i] = &SolDer2[i]; }*/ //return DphiDx2[x]; } void vel_ver(double phi[][N],double v,double c,int tsteps,double dt) { int t,x; double d1,d2,dp,DphiDx1[tsteps+1][N],DphiDx2[tsteps+1][N],dpdt[tsteps+1][N],p[tsteps+1][N]; for (t=0;t<tsteps;t++){ if (t==0){ for (x=0;x<N;x++){//inital conditions deriv2(phi,DphiDx2,t); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t][x]) - sin(3.*phi[t][x]); DphiDx1[t][x] = (phi[t][x+1] - phi[t][x])/dx; p[t][x] = -v*DphiDx1[t][x]; } } for (x=0;x<N;x++){//velocity-verlet phi[t+1][x] = phi[t][x] + dt*p[t][x] + (dt*dt/2)*dpdt[t][x]; p[t+1][x] = p[t][x] + (dt/2)*dpdt[t][x]; deriv2(phi,DphiDx2,t+1); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t+1][x]) - sin(3.*phi[t+1][x]); p[t+1][x] += (dt/2)*dpdt[t+1][x]; } } } So, this really isn't due to my overwriting the end of the Sol array. I've commented out both functions that I suspected of causing the problem (bisect or shoot) and inserted a print function. Two things happen. When I have code like below: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); B = shoot(Sol,A,c); printf("%lf",B); I get a segfault from the function, shoot. However, if I take away the shoot function so that I have: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); it gives me a segfault at the printf... Why!?

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  • Combining graphs in Mathematica

    - by pizziaolo
    Any idea how I can overlay the following two functions to compare them? ln[1]:= p1 = Plot[(E^((Pi/6)^(1/3)/x) (Pi/6)^(2/3))/((-1 + E^((Pi/6)^(1/3)/x))^2 x^2), {x, -2.2, 2.2}] ln[2]:= p2 = Plot[(E^((Pi/6)^(1/3)/t) (Pi/6)^(2/3))/((-1 + E^((Pi/6)^(1/3)/t))^2 t^2), {t, 0, 2.0}] When I try Show[p1,p2] it doesn't work

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  • fail2ban log parsing too slow on Raspberry Pi - options? [migrated]

    - by Gordon Morehouse
    I'm running fail2ban on a Raspberry Pi at 950MHz which I cannot overclock further. The Pi is occasionally subject to SYN floods on particular ports. I've set up iptables to throttle the rate of SYNs on the port of interest; when the throttle limits are exceeded, hosts which send SYNs are dropped into the REJECT chain and the particular SYN packet which exceeded the limit is logged. fail2ban then watches for these logged SYNs and, after seeing a few, temporarily bans the host for a short time (this is a transient issue in the app I'm working with). The problem is that the SYN floods can occasionally reach rates which are too fast for fail2ban to keep up with; I'll see 20-40 log messages per second, and eventually fail2ban falls behind and becomes ineffective. To add insult to injury, it continues consuming a LOT of CPU as it tries to catch up. I have verified that DROP chained packets from hosts already banned by fail2ban are not logged, and thus do not add to its load. What are my options here? I have a few ideas, but no clear path forward. Could I make the log-parse regex "easier" so it takes fewer cycles? Would using iptables --log-prefix to put a token near the start of the log message, and/or otherwise simplifying/altering the fail2ban regex help? Here is the current fail2ban config line containing a regex: failregex = kernel:.*?SRC=(?:::f{4,6}:)?(?P<host>[\w\-.^_]+) DST.*?SYN Is there a faster way for fail2ban to watch for the packets exceeding the limits than parsing kern.log? Could fail2ban be run under PyPy instead of CPython with minimal nonstandard wizardry (the OS is Raspbian 7, so, mostly Debian 7)? Is there something better than fail2ban that I could use to watch for the packets which exceed the SYN limits, and after N exceeds in X seconds, temporarily put the offending IP into the iptables DROP bucket, and take it out when the ban timer expires? Again, I'd vastly prefer a solution that uses as much software available in Debian as possible, though I can build Debian packages in a pinch.

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