negative zero - Page 25

How to add music file to C program in linux? do I have to download any extra codec? or Gstreamer is

- by Zero Cool

I want to add music file to my C program, how do I do it?

destructor being called by subclass

- by zero

I'm currently learning more about php objects and constructors/destructors, but i've noticed in my code that the parent class's destructor is being called twice, I thought it was because i was extending the first class to my second class and that the second class was calling it, but this is what the php docs say about that: Like constructors, parent destructors will not be called implicitly by the engine. In order to run a parent destructor, one would have to explicitly call parent::__destruct() in the destructor body. so if it is not being called by the subclass then is it because by extended the first class that i've made a reference to the parent class making it call itself twice or I'm I way off base here? the code: <?php class test{ public $test1 = "this is a test of a pulic property"; private $test2 = "this is a test of a private property"; protected $test3 = "this is a test of a protected property"; const hello = 900000; function __construct($h){ //echo 'this is the constructor test '.$h; } function x($x2){ echo ' this is fn x'.$x2; } function y(){ print "this is fn y"; } } $obj = new test("this is an \"arg\" sent to instance of test"); class hey extends test{ function hey(){ $this->x('<br>from the host with the most'); echo ' <br>from hey class'.$this->test3; } } $obj2 = new hey(); echo $obj2::hello; ?>

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Existing function to slice pandas object by axis number

- by Zero

Pandas has the following indexers: Object Type Indexers Series s.loc[indexer] DataFrame df.loc[row_indexer,column_indexer] Panel p.loc[item_indexer,major_indexer,minor_indexer] I would like to be able to index dynamically by axis, for example: df = pd.DataFrame(data=0, index=['row1', 'row2', 'row3'], columns=['col1', 'col2', col3']) df.index(['row1', 'row3'], axis=0) # index by rows df.index(['col1', 'col2'], axis=1) # index by columns Is there a built-in function that does this?

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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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Shell Script if else

- by user34104

#!/bin/bash echo "Int. a number" read num1 echo "Int. another numer" read num2 if ["$num1"="$num2"]; then echo "Equals" else echo "Dif" fi if["$num1"<0]; then echo "The number $num1 is negative" else if ["$num2"<0]; then echo "The number $num2 is negative" fi # this code is not working, i've something wrong when i see if the number is < 0. thanks

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Somebody knows why the sectors of the IBM floppy disk are named 1 to 8 (and not 0 to 7 )

- by Olivier Briand

I am now programming on a 8 bits Z80 computer with CP/M 2.2, (as a hobby) and the floppy disk format is IBM, 40 tracks, 8 sectors per track, 512 bytes per sector. free space is 154 Ko on each face of the disk. Why the sectors are indexed 1 to 8 (and not zero to seven, as usually is seen with computers)? The catalog of the floppy disk is on the track 1 (sector 1 to 4, 64 entries). I'm wondering is the catalog on track zero? Is the zero track reserved to included a system (as track 0 & 1 are reserved to the system on a CP/M floppy disk, and catalog is on track 2)?

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How to convert ISampleGrabber::BufferCB's buffer to a bitmap

- by user2509919

I am trying to use the ISampleGrabberCB::BufferCB to convert the current frame to bitmap using the following code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { try { Form1 form1 = new Form1("", "", ""); if (pictureReady == null) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); } Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); Bitmap bitmapOfCurrentFrame = new Bitmap(width, height, capturePitch, PixelFormat.Format24bppRgb, buffer); MessageBox.Show("Works"); form1.changepicturebox3(bitmapOfCurrentFrame); pictureReady.Set(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } return 0; } However this does not seem to be working. Additionally it seems to call this function when i press a button which runs the following code: public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } Once this code is ran I get a message box which shows 'Works' thus meaning my BufferCB must of been called however does not update my picture box with the current image. Is the BufferCB not called after every new frame? If so why do I not recieve the 'Works' message box? Finally is it possible to convert every new frame into a bitmap (this is used for later processing) using BufferCB and if so how? Edited code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); CopyMemory(imageBuffer, buffer, bufferLength); Decode(buffer); return 0; } public Image Decode(IntPtr imageData) { var bitmap = new Bitmap(width, height, pitch, PixelFormat.Format24bppRgb, imageBuffer); bitmap.RotateFlip(RotateFlipType.RotateNoneFlipY); Form1 form1 = new Form1("", "", ""); form1.changepicturebox3(bitmap); bitmap.Save("C:\\Users\\...\\Desktop\\A2 Project\\barcode.jpg"); return bitmap; } Button code: public void getFrameFromWebcam() { if (iPtr != IntPtr.Zero) { Marshal.FreeCoTaskMem(iPtr); iPtr = IntPtr.Zero; } //Get Image iPtr = sampleGrabberCallBack.getFrame(); Bitmap bitmapOfFrame = new Bitmap(sampleGrabberCallBack.width, sampleGrabberCallBack.height, sampleGrabberCallBack.capturePitch, PixelFormat.Format24bppRgb, iPtr); bitmapOfFrame.RotateFlip(RotateFlipType.RotateNoneFlipY); barcodeReader(bitmapOfFrame); } public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } I also still need to press the button to run the BufferCB Thanks for reading.

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Defining recursive algebraic data types in XML XSD

- by Ben Challenor

Imagine I have a recursive algebraic data type like this (Haskell syntax): data Expr = Zero | One | Add Expr Expr | Mul Expr Expr I'd like to represent this in XML, and I'd like an XSD schema for it. I have figured out how to achieve this syntax: <Expr> <Add> <Expr> <Zero/> </Expr> <Expr> <Mul> <Expr> <One/> </Expr> <Expr> <Add> <Expr> <One/> </Expr> <Expr> <One/> </Expr> </Add> </Expr> </Mul> </Expr> </Add> </Expr> with this schema: <xs:complexType name="Expr"> <xs:choice minOccurs="1" maxOccurs="1"> <xs:element minOccurs="1" maxOccurs="1" name="Zero" type="Zero" /> <xs:element minOccurs="1" maxOccurs="1" name="One" type="One" /> <xs:element minOccurs="1" maxOccurs="1" name="Add" type="Add" /> <xs:element minOccurs="1" maxOccurs="1" name="Mul" type="Mul" /> </xs:choice> </xs:complexType> <xs:complexType name="Zero"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="One"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="Add"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> <xs:complexType name="Mul"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> But what I really want is this syntax: <Add> <Zero/> <Mul> <One/> <Add> <One/> <One/> </Add> </Mul> </Add> Is this possible? Thanks!

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SQL SERVER – Removing Leading Zeros From Column in Table

- by pinaldave

Some questions surprises me and make me write code which I have never explored before. Today was similar experience as well. I have always received the question regarding how to reserve leading zeroes in SQL Server while displaying them on the SSMS or another application. I have written articles on this subject over here. SQL SERVER – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – UDF – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – Preserve Leading Zero While Coping to Excel from SSMS Today I received a very different question where the user wanted to remove leading zero and white space. I am using the same sample sent by user in this example. USE tempdb GO -- Create sample table CREATE TABLE Table1 (Col1 VARCHAR(100)) INSERT INTO Table1 (Col1) SELECT '0001' UNION ALL SELECT '000100' UNION ALL SELECT '100100' UNION ALL SELECT '000 0001' UNION ALL SELECT '00.001' UNION ALL SELECT '01.001' GO -- Original data SELECT * FROM Table1 GO -- Remove leading zeros SELECT SUBSTRING(Col1, PATINDEX('%[^0 ]%', Col1 + ' '), LEN(Col1)) FROM Table1 GO -- Clean up DROP TABLE Table1 GO Here is the resultset of above script. It will remove any leading zero or space and will display the number accordingly. This problem is a very generic problem and I am confident there are alternate solutions to this problem as well. If you have an alternate solution or can suggest a sample data which does not satisfy the SUBSTRING solution proposed, I will be glad to include them in follow up blog post with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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Ogre 3d and bullet physics interaction

- by Tim

I have been playing around with Ogre3d and trying to integrate bullet physics. I have previously somewhat successfully got this functionality working with irrlicht and bullet and I am trying to base this on what I had done there, but modifying it to fit with Ogre. It is working but not correctly and I would like some help to understand what it is I am doing wrong. I have a state system and when I enter the "gamestate" I call some functions such as setting up a basic scene, creating the physics simulation. I am doing that as follows. void GameState::enter() { ... // Setup Physics btBroadphaseInterface *BroadPhase = new btAxisSweep3(btVector3(-1000,-1000,-1000), btVector3(1000,1000,1000)); btDefaultCollisionConfiguration *CollisionConfiguration = new btDefaultCollisionConfiguration(); btCollisionDispatcher *Dispatcher = new btCollisionDispatcher(CollisionConfiguration); btSequentialImpulseConstraintSolver *Solver = new btSequentialImpulseConstraintSolver(); World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration); ... createScene(); } In the createScene method I add a light and try to setup a "ground" plane to act as the ground for things to collide with.. as follows. I expect there is issues with this as I get objects colliding with the ground but half way through it and they glitch around like crazy on collision. void GameState::createScene() { m_pSceneMgr->createLight("Light")->setPosition(75,75,75); // Physics // As a test we want a floor plane for things to collide with Ogre::Entity *ent; Ogre::Plane p; p.normal = Ogre::Vector3(0,1,0); p.d = 0; Ogre::MeshManager::getSingleton().createPlane( "FloorPlane", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, p, 200000, 200000, 20, 20, true, 1, 9000,9000,Ogre::Vector3::UNIT_Z); ent = m_pSceneMgr->createEntity("floor", "FloorPlane"); ent->setMaterialName("Test/Floor"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(ent); btTransform Transform; Transform.setIdentity(); Transform.setOrigin(btVector3(0,1,0)); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btCollisionShape *Shape = new btStaticPlaneShape(btVector3(0,1,0),0); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(0, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(0, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; // End Physics } I then have a method to create a cube and give it rigid body physics properties. I know there will be errors here as I get the items colliding with the ground but not with each other properly. So I would appreciate some input on what I am doing wrong. void GameState::CreateBox(const btVector3 &TPosition, const btVector3 &TScale, btScalar TMass) { Ogre::Vector3 size = Ogre::Vector3::ZERO; Ogre::Vector3 pos = Ogre::Vector3::ZERO; Ogre::Vector3 scale = Ogre::Vector3::ZERO; pos.x = TPosition.getX(); pos.y = TPosition.getY(); pos.z = TPosition.getZ(); scale.x = TScale.getX(); scale.y = TScale.getY(); scale.z = TScale.getZ(); Ogre::Entity *entity = m_pSceneMgr->createEntity( "Box" + Ogre::StringConverter::toString(m_pNumEntities), "cube.mesh"); entity->setCastShadows(true); Ogre::AxisAlignedBox boundingB = entity->getBoundingBox(); size = boundingB.getSize(); //size /= 2.0f; // Only the half needed? //size *= 0.96f; // Bullet margin is a bit bigger so we need a smaller size entity->setMaterialName("Test/Cube"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(entity); node->setPosition(pos); //node->scale(scale); // Physics btTransform Transform; Transform.setIdentity(); Transform.setOrigin(TPosition); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btVector3 HalfExtents(TScale.getX()*0.5f,TScale.getY()*0.5f,TScale.getZ()*0.5f); btCollisionShape *Shape = new btBoxShape(HalfExtents); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(TMass, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; } Then in the GameState::update() method which which runs every frame to handle input and render etc I call an UpdatePhysics method to update the physics simulation. void GameState::UpdatePhysics(unsigned int TDeltaTime) { World->stepSimulation(TDeltaTime * 0.001f, 60); btRigidBody *TObject; for(std::vector<btRigidBody *>::iterator it = Objects.begin(); it != Objects.end(); ++it) { // Update renderer Ogre::SceneNode *node = static_cast<Ogre::SceneNode *>((*it)->getUserPointer()); TObject = *it; // Set position btVector3 Point = TObject->getCenterOfMassPosition(); node->setPosition(Ogre::Vector3((float)Point[0], (float)Point[1], (float)Point[2])); // set rotation btVector3 EulerRotation; QuaternionToEuler(TObject->getOrientation(), EulerRotation); node->setOrientation(1,(Ogre::Real)EulerRotation[0], (Ogre::Real)EulerRotation[1], (Ogre::Real)EulerRotation[2]); //node->rotate(Ogre::Vector3(EulerRotation[0], EulerRotation[1], EulerRotation[2])); } } void GameState::QuaternionToEuler(const btQuaternion &TQuat, btVector3 &TEuler) { btScalar W = TQuat.getW(); btScalar X = TQuat.getX(); btScalar Y = TQuat.getY(); btScalar Z = TQuat.getZ(); float WSquared = W * W; float XSquared = X * X; float YSquared = Y * Y; float ZSquared = Z * Z; TEuler.setX(atan2f(2.0f * (Y * Z + X * W), -XSquared - YSquared + ZSquared + WSquared)); TEuler.setY(asinf(-2.0f * (X * Z - Y * W))); TEuler.setZ(atan2f(2.0f * (X * Y + Z * W), XSquared - YSquared - ZSquared + WSquared)); TEuler *= RADTODEG; } I seem to have issues with the cubes not colliding with each other and colliding strangely with the ground. I have tried to capture the effect with the attached image. I would appreciate any help in understanding what I have done wrong. Thanks. EDIT : Solution The following code shows the changes I made to get accurate physics. void GameState::createScene() { m_pSceneMgr->createLight("Light")->setPosition(75,75,75); // Physics // As a test we want a floor plane for things to collide with Ogre::Entity *ent; Ogre::Plane p; p.normal = Ogre::Vector3(0,1,0); p.d = 0; Ogre::MeshManager::getSingleton().createPlane( "FloorPlane", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, p, 200000, 200000, 20, 20, true, 1, 9000,9000,Ogre::Vector3::UNIT_Z); ent = m_pSceneMgr->createEntity("floor", "FloorPlane"); ent->setMaterialName("Test/Floor"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(ent); btTransform Transform; Transform.setIdentity(); // Fixed the transform vector here for y back to 0 to stop the objects sinking into the ground. Transform.setOrigin(btVector3(0,0,0)); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); btCollisionShape *Shape = new btStaticPlaneShape(btVector3(0,1,0),0); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(0, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(0, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; // End Physics } void GameState::CreateBox(const btVector3 &TPosition, const btVector3 &TScale, btScalar TMass) { Ogre::Vector3 size = Ogre::Vector3::ZERO; Ogre::Vector3 pos = Ogre::Vector3::ZERO; Ogre::Vector3 scale = Ogre::Vector3::ZERO; pos.x = TPosition.getX(); pos.y = TPosition.getY(); pos.z = TPosition.getZ(); scale.x = TScale.getX(); scale.y = TScale.getY(); scale.z = TScale.getZ(); Ogre::Entity *entity = m_pSceneMgr->createEntity( "Box" + Ogre::StringConverter::toString(m_pNumEntities), "cube.mesh"); entity->setCastShadows(true); Ogre::AxisAlignedBox boundingB = entity->getBoundingBox(); // The ogre bounding box is slightly bigger so I am reducing it for // use with the rigid body. size = boundingB.getSize()*0.95f; entity->setMaterialName("Test/Cube"); Ogre::SceneNode *node = m_pSceneMgr->getRootSceneNode()->createChildSceneNode(); node->attachObject(entity); node->setPosition(pos); node->showBoundingBox(true); //node->scale(scale); // Physics btTransform Transform; Transform.setIdentity(); Transform.setOrigin(TPosition); // Give it to the motion state btDefaultMotionState *MotionState = new btDefaultMotionState(Transform); // I got the size of the bounding box above but wasn't using it to set // the size for the rigid body. This now does. btVector3 HalfExtents(size.x*0.5f,size.y*0.5f,size.z*0.5f); btCollisionShape *Shape = new btBoxShape(HalfExtents); // Add Mass btVector3 LocalInertia; Shape->calculateLocalInertia(TMass, LocalInertia); // CReate the rigid body object btRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia); // Store a pointer to the Ogre Node so we can update it later RigidBody->setUserPointer((void *) (node)); // Add it to the physics world World->addRigidBody(RigidBody); Objects.push_back(RigidBody); m_pNumEntities++; } void GameState::UpdatePhysics(unsigned int TDeltaTime) { World->stepSimulation(TDeltaTime * 0.001f, 60); btRigidBody *TObject; for(std::vector<btRigidBody *>::iterator it = Objects.begin(); it != Objects.end(); ++it) { // Update renderer Ogre::SceneNode *node = static_cast<Ogre::SceneNode *>((*it)->getUserPointer()); TObject = *it; // Set position btVector3 Point = TObject->getCenterOfMassPosition(); node->setPosition(Ogre::Vector3((float)Point[0], (float)Point[1], (float)Point[2])); // Convert the bullet Quaternion to an Ogre quaternion btQuaternion btq = TObject->getOrientation(); Ogre::Quaternion quart = Ogre::Quaternion(btq.w(),btq.x(),btq.y(),btq.z()); // use the quaternion with setOrientation node->setOrientation(quart); } } The QuaternionToEuler function isn't needed so that was removed from code and header files. The objects now collide with the ground and each other appropriately.

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Stencil mask with AlphaTestEffect

- by Brendan Wanlass

I am trying to pull off the following effect in XNA 4.0: http://eng.utah.edu/~brendanw/question.jpg The purple area has 50% opacity. I have gotten pretty close with the following code: public static DepthStencilState AlwaysStencilState = new DepthStencilState() { StencilEnable = true, StencilFunction = CompareFunction.Always, StencilPass = StencilOperation.Replace, ReferenceStencil = 1, DepthBufferEnable = false, }; public static DepthStencilState EqualStencilState = new DepthStencilState() { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.Keep, ReferenceStencil = 1, DepthBufferEnable = false, }; ... if (_alphaEffect == null) { _alphaEffect = new AlphaTestEffect(_spriteBatch.GraphicsDevice); _alphaEffect.AlphaFunction = CompareFunction.LessEqual; _alphaEffect.ReferenceAlpha = 129; Matrix projection = Matrix.CreateOrthographicOffCenter(0, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferWidth, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferHeight, 0, 0, 1); _alphaEffect.Projection = world.SystemManager.GetSystem<RenderSystem>().Camera.View * projection; } _mask = new RenderTarget2D(_spriteBatch.GraphicsDevice, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferWidth, _spriteBatch.GraphicsDevice.PresentationParameters.BackBufferHeight, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8); _spriteBatch.GraphicsDevice.SetRenderTarget(_mask); _spriteBatch.GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.Stencil, Color.Transparent, 0, 0); _spriteBatch.Begin(SpriteSortMode.Immediate, null, null, AlwaysStencilState, null, _alphaEffect); _spriteBatch.Draw(sprite.Texture, position, sprite.SourceRectangle,Color.White, 0f, sprite.Origin, 1f, SpriteEffects.None, 0); _spriteBatch.End(); _spriteBatch.Begin(SpriteSortMode.Immediate, null, null, EqualStencilState, null, null); _spriteBatch.Draw(_maskTex, new Vector2(x * _maskTex.Width, y * _maskTex.Height), null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, 0); _spriteBatch.End(); _spriteBatch.GraphicsDevice.SetRenderTarget(null); _spriteBatch.GraphicsDevice.Clear(Color.Black); _spriteBatch.Begin(); _spriteBatch.Draw((Texture2D)_mask, Vector2.Zero, null, Color.White, 0f, Vector2.Zero, 1f, SpriteEffects.None, layer/max_layer); _spriteBatch.End(); My problem is, I can't get the AlphaTestEffect to behave. I can either mask over the semi-transparent purple junk and fill it in with the green design, or I can draw over the completely opaque grassy texture. How can I specify the exact opacity that needs to be replace with the green design?

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Correct For Loop Design

- by Yttrill

What is the correct design for a for loop? Felix currently uses if len a > 0 do for var i in 0 upto len a - 1 do println a.[i]; done done which is inclusive of the upper bound. This is necessary to support the full range of values of a typical integer type. However the for loop shown does not support zero length arrays, hence the special test, nor will the subtraction of 1 work convincingly if the length of the array is equal to the number of integers. (I say convincingly because it may be that 0 - 1 = maxval: this is true in C for unsigned int, but are you sure it is true for unsigned char without thinking carefully about integral promotions?) The actual implementation of the for loop by my compiler does correctly handle 0 but this requires two tests to implement the loop: continue: if not (i <= bound) goto break body if i == bound goto break ++i goto continue break: Throw in the hand coded zero check in the array example and three tests are needed. If the loop were exclusive it would handle zero properly, avoiding the special test, but there'd be no way to express the upper bound of an array with maximum size. Note the C way of doing this: for(i=0; predicate(i); increment(i)) has the same problem. The predicate is tested after the increment, but the terminating increment is not universally valid! There is a general argument that a simple exclusive loop is enough: promote the index to a large type to prevent overflow, and assume no one will ever loop to the maximum value of this type.. but I'm not entirely convinced: if you promoted to C's size_t and looped from the second largest value to the largest you'd get an infinite loop!

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Red Dot Scope Makes Sighting In Long Lenses a Snap

- by Jason Fitzpatrick

If you’ve ever used a high power lens, you know how tricky it can be to sight a distant subject as the field of view through the lens is so tiny. This hack takes care of that problem by using a zero-magnification red dot rifle scope. Chris Malcolm enjoys photographing birds and other wildlife with high power lenses. The problem, when shooting with huge 500mm lens and other high power lenses, is that they’re practically telescopes and acquiring a fast moving target like a bird using a through-the-lens technique is very tricky. Malcolm’s solution hinges on mounting a zero-magnification red dot rifle scope in parallel with the lens. His mock up is a bit unpolished (although we can understand not wanting to run out and buy a brand new black scope just for the experiment) but works great to get him on target. Hit up the link below to read more about his build, how be created the rail mount for the scope, and why he opted to mount it to the barrel of the lens and not the hot shoe mount on the camera. 500mm Reflex Lens with Red Dot Sight [via DIY Photography] Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos HTG Explains: What Can You Find in an Email Header?

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"Accumulate" buffer results in XNA4?

- by Utkarsh Sinha

I'm trying to simulate a "heightmap" buffer in XNA4.0 but the results don't look correct. Here's what I'm hoping to achieve: http://www.youtube.com/watch?feature=player_detailpage&v=-Q6ISVaM5Ww#t=517s (8:38). From what I understand, here are the steps to reach there: Pass height buffer + current entity's heightmap Generate a stencil and update the height buffer Render sprite+stencil For now, I'm just trying to get the height buffer thing to work. So here's the problem. Inside the draw loop, I do the following: Create a new render target & set it Draw the heightmap with a sprite batch(no shaders) graphicsDevice.SetRenderTarget(null) Draw the rendertarget with SpriteBatch I expected to see all entities' heightmaps. But only the last entity's heightmap is visible. Any hints on what I'm doing wrong? Here's the code inside the draw loop: RenderTarget2D tempDepthStencil = new RenderTarget2D(graphicsDevice, graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, false, graphicsDevice.DisplayMode.Format, DepthFormat.None); graphicsDevice.SetRenderTarget(tempDepthStencil); // Gather depth information SpriteBatch depthStencilSpriteBatch = new SpriteBatch(graphicsDevice); depthStencilSpriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullCounterClockwise); depthStencilSpriteBatch.Draw(texHeightmap, pos, null, Color.White, 0, Vector2.Zero, 1, spriteEffects, 1); depthStencilSpriteBatch.End(); graphicsDevice.SetRenderTarget(null); SpriteBatch b1 = new SpriteBatch(graphicsDevice); b1.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, null, null, null, null); b1.Draw((Texture2D)tempDepthStencil, Vector2.Zero, null, Color.White, 0, Vector2.Zero, 1, spriteEffects, 1); b1.End();

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Upgrading Oracle Siebel CRM Application Without Downtime

- by Doug Reid

Oracle’s Siebel Customer Relationship Management (CRM) software helps organizations differentiate their businesses to achieve top- and bottom-line growth. Siebel CRM delivers comprehensive solutions that are tailored to more than 20 different industries. As Siebel CRM implementations have evolved into mission critical, operational business processes that must operate 24/7, companies are finding it increasingly difficult to afford the downtime typically required to perform an in-place upgrade. Without these upgrades, businesses loose out on critical new features and functionality. With Oracle GoldenGate, customers don’t have to choose between upgrades and outages. Oracle GoldenGate allows Siebel CRM customers to perform upgrades with zero downtime. Now Siebel customers can always take advantages of the latest innovations in customer relationship management without having to worry about potential lost revenue due to downtime. Oracle GoldenGate provides three different deployment models for Siebel CRM zero downtime upgrades that are designed to meet differing customer requirements. These range from a basic unidirectional model, which is designed to work out-of-the-box, to the most sophisticated active-active model for phased migrations. If you have mission-critical Siebel CRM implementations I recommend that you watch the screencast below to learn how you can begin taking advantage of all the latest Siebel enhancements without having any downtime. This screencast is also available on Oracle Media Network and Oracle's YouTube channel. For even more details I recommend reading the whitepaper Upgrading Siebel CRM with Zero Downtime .

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How do I implement SkyBox in xna 4.0 Reach Profile (for Windows Phone 7)?

- by Biny

I'm trying to Implement SkyBox in my phone game. Most of the samples in the web are for HiDef profile, and they are using custom effects (that not supported on Windows Phone). I've tried to follow this guide. But for some reason my SkyBox is not rendered. This is my SkyBox class: using System; using System.Collections.Generic; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using Rocuna.Core; using Rocuna.GameEngine.Graphics; using Rocuna.GameEngine.Graphics.Components; namespace Rocuna.GameEngine.Extension.WP7.Graphics { /// <summary> /// Sky box element for phone games. /// </summary> public class SkyBox : SkyBoxBase { /// <summary> /// Initializes a new instance of the <see cref="SkyBoxBase"/> class. /// </summary> /// <param name="game">The Game that the game component should be attached to.</param> public SkyBox(TextureCube cube, Game game) : base(game) { Cube = cube; CubeFaces = new Texture2D[6]; PositionOffset = new Vector3(20, 20, 20); CreateGraphic(512); StripTexturesFromCube(); InitializeData(Game.GraphicsDevice); } #region Properties /// <summary> /// Gets or sets the position offset. /// </summary> /// <value> /// The position offset. /// </value> public Vector3 PositionOffset { get; set; } /// <summary> /// Gets or sets the position. /// </summary> /// <value> /// The position. /// </value> public Vector3 Position { get; set; } /// <summary> /// Gets or sets the cube. /// </summary> /// <value> /// The cube. /// </value> public TextureCube Cube { get; set; } /// <summary> /// Gets or sets the pixel array. /// </summary> /// <value> /// The pixel array. /// </value> public Color[] PixelArray { get; set; } /// <summary> /// Gets or sets the cube faces. /// </summary> /// <value> /// The cube faces. /// </value> public Texture2D[] CubeFaces { get; set; } /// <summary> /// Gets or sets the vertex buffer. /// </summary> /// <value> /// The vertex buffer. /// </value> public VertexBuffer VertexBuffer { get; set; } /// <summary> /// Gets or sets the index buffer. /// </summary> /// <value> /// The index buffer. /// </value> public IndexBuffer IndexBuffer { get; set; } /// <summary> /// Gets or sets the effect. /// </summary> /// <value> /// The effect. /// </value> public BasicEffect Effect { get; set; } #endregion protected override void LoadContent() { } public override void Update(GameTime gameTime) { var camera = Game.GetService<GraphicManager>().CurrentCamera; this.Position = camera.Position + PositionOffset; base.Update(gameTime); } public override void Draw(GameTime gameTime) { DrawOrder = int.MaxValue; var graphics = Effect.GraphicsDevice; graphics.DepthStencilState = new DepthStencilState() { DepthBufferEnable = false }; graphics.RasterizerState = new RasterizerState() { CullMode = CullMode.None }; graphics.BlendState = new BlendState(); graphics.SamplerStates[0] = SamplerState.AnisotropicClamp; graphics.SetVertexBuffer(VertexBuffer); graphics.Indices = IndexBuffer; Effect.Texture = CubeFaces[0]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 0, 2); Effect.Texture = CubeFaces[1]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 6, 2); Effect.Texture = CubeFaces[2]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 12, 2); Effect.Texture = CubeFaces[3]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 18, 2); Effect.Texture = CubeFaces[4]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 24, 2); Effect.Texture = CubeFaces[5]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 30, 2); base.Draw(gameTime); } #region Fields private List<VertexPositionNormalTexture> _vertices = new List<VertexPositionNormalTexture>(); private List<ushort> _indices = new List<ushort>(); #endregion #region Private methods private void InitializeData(GraphicsDevice graphicsDevice) { VertexBuffer = new VertexBuffer(graphicsDevice, typeof(VertexPositionNormalTexture), _vertices.Count, BufferUsage.None); VertexBuffer.SetData<VertexPositionNormalTexture>(_vertices.ToArray()); // Create an index buffer, and copy our index data into it. IndexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort), _indices.Count, BufferUsage.None); IndexBuffer.SetData<ushort>(_indices.ToArray()); // Create a BasicEffect, which will be used to render the primitive. Effect = new BasicEffect(graphicsDevice); Effect.TextureEnabled = true; Effect.EnableDefaultLighting(); } private void CreateGraphic(float size) { Vector3[] normals = { Vector3.Right, Vector3.Left, Vector3.Up, Vector3.Down, Vector3.Backward, Vector3.Forward, }; Vector2[] textureCoordinates = { Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, }; var index = 0; foreach (var normal in normals) { var side1 = new Vector3(normal.Z, normal.X, normal.Y); var side2 = Vector3.Cross(normal, side1); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 1); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 3); AddVertex((normal - side1 - side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal - side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 - side2) * size / 2, normal, textureCoordinates[index++]); } } protected void StripTexturesFromCube() { PixelArray = new Color[Cube.Size * Cube.Size]; for (int s = 0; s < CubeFaces.Length; s++) { CubeFaces[s] = new Texture2D(Game.GraphicsDevice, Cube.Size, Cube.Size, false, SurfaceFormat.Color); switch (s) { case 0: Cube.GetData<Color>(CubeMapFace.PositiveX, PixelArray); CubeFaces[s].SetData<Color>(PixelArray); break; case 1: Cube.GetData(CubeMapFace.NegativeX, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 2: Cube.GetData(CubeMapFace.PositiveY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 3: Cube.GetData(CubeMapFace.NegativeY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 4: Cube.GetData(CubeMapFace.PositiveZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 5: Cube.GetData(CubeMapFace.NegativeZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; } } } protected void AddVertex(Vector3 position, Vector3 normal, Vector2 textureCoordinates) { _vertices.Add(new VertexPositionNormalTexture(position, normal, textureCoordinates)); } protected void AddIndex(int index) { if (index > ushort.MaxValue) throw new ArgumentOutOfRangeException("index"); _indices.Add((ushort)index); } protected int CurrentVertex { get { return _vertices.Count; } } #endregion } }

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How to determine if a 3D voxel-based room is sealed, efficiently

- by NigelMan1010

I've been having some issues with efficiently determining if large rooms are sealed in a voxel-based 3D rooms. I'm at a point where I have tried my hardest to solve the problem without asking for help, but not tried enough to give up, so I'm asking for help. To clarify, sealed being that there are no holes in the room. There are oxygen sealers, which check if the room is sealed, and seal depending on the oxygen input level. Right now, this is how I'm doing it: Starting at the block above the sealer tile (the vent is on the sealer's top face), recursively loop through in all 6 adjacent directions If the adjacent tile is a full, non-vacuum tile, continue through the loop If the adjacent tile is not full, or is a vacuum tile, check if it's adjacent blocks are, recursively. Each time a tile is checked, decrement a counter If the count hits zero, if the last block is adjacent to a vacuum tile, return that the area is unsealed If the count hits zero and the last block is not a vacuum tile, or the recursive loop ends (no vacuum tiles left) before the counter is zero, the area is sealed If the area is not sealed, run the loop again with some changes: Checking adjacent blocks for "breathable air" tile instead of a vacuum tile Instead of using a decrementing counter, continue until no adjacent "breathable air" tiles are found. Once loop is finished, set each checked block to a vacuum tile. Here's the code I'm using: http://pastebin.com/NimyKncC The problem: I'm running this check every 3 seconds, sometimes a sealer will have to loop through hundreds of blocks, and a large world with many oxygen sealers, these multiple recursive loops every few seconds can be very hard on the CPU. I was wondering if anyone with more experience with optimization can give me a hand, or at least point me in the right direction. Thanks a bunch.

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How to handle circle penetration

- by Kaertserif

I've been working on cirlce to circle collision and have gotten the intersection method working correctly, but I'm having problems using the returned values to actually seperate the circles from one another. This is the method which calculates the depth of the circle collision public static Vector2 GetIntersectionDepth(Circle a, Circle b) { float xValue = a.Center.X - b.Center.X; float yValue = a.Center.Y - b.Center.Y; Vector2 depth = Vector2.Zero; float distance = Vector2.Distance(a.Center, b.Center); if (a.Radius + b.Radius > distance) { float result = (a.Radius + b.Radius) - distance; depth.X = (float)Math.Cos(result); depth.Y = (float)Math.Sin(result); } return depth; } This is where I'm trying to apply the values to actually seperate the circles. Vector2 depth = Vector2.Zero; for (int i = 0; i < circlePositions.Count; i++) { for (int j = 0; j < circlePositions.Count; j++) { Circle bounds1 = new Circle(circlePositions[i], circle.Width / 2); Circle bounds2 = new Circle(circlePositions[j], circle.Width / 2); if(i != j) depth = CircleToCircleIntersection.GetIntersectionDepth(bounds1, bounds2); if (depth != Vector2.Zero) { circlePositions[i] = new Vector2(circlePositions[i].X + depth.X, circlePositions[i].Y + depth.Y); } } } If you can offer any help in this I would really appreciate it.

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Regular expressions in findstr

- by Johannes Rössel

I'm doing a little string validation with findstr and its /r flag to allow for regular expressions. In particular I'd like to validate integers. The regex ^[0-9][0-9]*$ worked fine for non-negative numbers but since I now support negative numbers as well I tried ^([1-9][0-9]*|0|-[1-9][0-9]*)$ for either positive or negative integers or zero. The regex works fine theoretically. I tested it in PowerShell and it matches what I want. However, with findstr /r /c:"^([1-9][0-9]*|0|-[1-9][0-9]*)$" it doesn't. While I know that findstr doesn't have the most advanced regex support (even below Notepad++ which is probably quite an achievement), I would have expected such simple expressions to work. Any ideas what I'm doing wrong here?

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problem in leigeber's sorting

- by developer

iam using leigeber's sorting javascript to sort my data on my page......i took the js from here :- leigeber's sorting javascript Now this is shwoing highlighted sorted column and all and its all perfect.Now iam having some negative and some positive values in my data and i want to show those negative data in red color and positive in green.This whole sorting thing is using js and css to do the highlighting and sorting.Iam a bit confused now and cant make it out that how i can assign red color to the negative ones and green to the positive ones as js is returning the data as an object i.e. a complete row and i cant make 1 column's data red or green.Will it be done by js itself or with the help of stylesheet to find -ves and +ves.Im totally lost and dont know how to do it.Please help!!!! this is an example of hte data iam using this whole sorting thing on:- -Name- -Price- -loss- -Pts- abc 361.15 -5.68 -21.75 abc2 1072.35 -5.24 -59.25 abc3 512.35 5.24 28.35 abc4 335.2 -5.02 -17.7 abc5 318.6 5.01 -16.8 abc6 76.15 -4.15 3.3

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Complicated MySQL query?

- by Scott

I have two tables: RatingsTable that contains a ratingname and a bit whether it is a positive or negative rating: Good 1 Bad 0 Fun 1 Boring 0 FeedbackTable that contains feedback on things...the person rating, the rating and the thing rated. The feedback can be determined if it's a positive or negative rating based on RatingsTable. Jim Chicken Good Jim Steak Bad Ted Waterskiing Fun Ted Hiking Fun Nancy Hiking Boring I am trying to write an efficient MySQL query for the following: On a page, I want to display the the top 'things' that have the highest proportional positive ratings. I want to be sure that the items from the feedback table are unique...meaning, that if Jim has rated Chicken Good 20 times...it should only be counted once. At some point I will want to require a minimum number of ratings (at least 10) to be counted for this page as well. I'll want to to do the same for highest proportional negative ratings, but I am sure I can tweak the one for positive accordingly.

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How does SET works with property in C#?

- by Richard77

Hello, I'd like to know how set works in a property when it does more than just setting the value of a private member variable. Let's say I've a private member in my class (private int myInt). For instance, I can make sure that the the value returned is not negative get { if(myInt < 0) myInt = 0; return myInt; } With SET, all I can do is affecting the private variable like so set { myInt = value; } I didn't see in any book how I can do more than that. How about if I wan't to do some operation before affecting the value to myInt? Let's say: If the value is negative, affect 0 to myInt. set { //Check if the value is non-negative, otherwise affect the 0 to myInt } Thanks for helping

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mciSendString cannot save to directory path

- by robUK

Hello, VS C# 2008 SP1 I have a created a small application that records and plays audio. However, my application needs to save the wave file to the application data directory on the users computer. The mciSendString takes a C style string as a parameter and has to be in 8.3 format. However, my problem is I can't get it to save. And what is strange is sometime it does and sometimes it doesn't. Howver, most of the time is failes. However, if I save directly to the C drive it works first time everything. I have used 3 different methods that I have coded below. The error number that I get when it fails is 286."The file was not saved. Make sure your system has sufficient disk space or has an intact network connection" Many thanks for any suggestins, [DllImport("winmm.dll",CharSet=CharSet.Auto)] private static extern uint mciSendString([MarshalAs(UnmanagedType.LPTStr)] string command, StringBuilder returnValue, int returnLength, IntPtr winHandle); [DllImport("winmm.dll", CharSet = CharSet.Auto)] private static extern int mciGetErrorString(uint errorCode, StringBuilder errorText, int errorTextSize); [DllImport("Kernel32.dll", CharSet=CharSet.Auto)] private static extern int GetShortPathName([MarshalAs(UnmanagedType.LPTStr)] string longPath, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder shortPath, int length); // Stop recording private void StopRecording() { // Save recorded voice string shortPath = this.shortPathName(); string formatShortPath = string.Format("save recsound \"{0}\"", shortPath); uint result = 0; StringBuilder errorTest = new StringBuilder(256); // C:\DOCUME~1\Steve\APPLIC~1\Test.wav // Fails result = mciSendString(string.Format("{0}", formatShortPath), null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // command line convention - fails result = mciSendString("save recsound \"C:\\DOCUME~1\\Steve\\APPLIC~1\\Test.wav\"", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // 8.3 short format - fails result = mciSendString(@"save recsound C:\DOCUME~1\Steve\APPLIC~1\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // Save to C drive works everytime. result = mciSendString(@"save recsound C:\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); mciSendString("close recsound ", null, 0, IntPtr.Zero); } // Get the short path name so that the mciSendString can save the recorded wave file private string shortPathName() { string shortPath = string.Empty; long length = 0; StringBuilder buffer = new StringBuilder(256); // Get the length of the path length = GetShortPathName(this.saveRecordingPath, buffer, 256); shortPath = buffer.ToString(); return shortPath; }

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Releasing an OLE IStorage file handle in C#

- by Bernard Darnton

I'm trying to embed a PDF file into a Word document using the OLE technique described here: http://blogs.msdn.com/brian_jones/archive/2009/07/21/embedding-any-file-type-like-pdf-in-an-open-xml-file.aspx I've tried to implement to C++ code provided in C# so that the whole project's in one place and am almost there except for one roadblock. When I try to feed the generated OLE object binary data into the Word document I get an IOException. IOException: The process cannot access the file 'C:\Wherever\Whatever.pdf.bin' because it is being used by another process. There is a file handle open the .bin file and I don't know how to get rid of it. I don't know a huge amount about COM - I'm winging it here - and I don't know where the file handle is or how to release it. Here's what my C#-ised code looks like. What am I missing? public void ExportOleFile(string oleOutputFileName, string emfOutputFileName) { OLE32.IStorage storage; var result = OLE32.StgCreateStorageEx( oleOutputFileName, OLE32.STGM.STGM_READWRITE | OLE32.STGM.STGM_SHARE_EXCLUSIVE | OLE32.STGM.STGM_CREATE | OLE32.STGM.STGM_TRANSACTED, OLE32.STGFMT.STGFMT_DOCFILE, 0, IntPtr.Zero, IntPtr.Zero, ref OLE32.IID_IStorage, out storage ); var CLSID_NULL = Guid.Empty; OLE32.IOleObject pOle; result = OLE32.OleCreateFromFile( ref CLSID_NULL, _inputFileName, ref OLE32.IID_IOleObject, OLE32.OLERENDER.OLERENDER_NONE, IntPtr.Zero, null, storage, out pOle ); result = OLE32.OleRun(pOle); IntPtr unknownFromOle = Marshal.GetIUnknownForObject(pOle); IntPtr unknownForDataObj; Marshal.QueryInterface(unknownFromOle, ref OLE32.IID_IDataObject, out unknownForDataObj); var pdo = Marshal.GetObjectForIUnknown(unknownForDataObj) as IDataObject; var fetc = new FORMATETC(); fetc.cfFormat = (short)OLE32.CLIPFORMAT.CF_ENHMETAFILE; fetc.dwAspect = DVASPECT.DVASPECT_CONTENT; fetc.lindex = -1; fetc.ptd = IntPtr.Zero; fetc.tymed = TYMED.TYMED_ENHMF; var stgm = new STGMEDIUM(); stgm.unionmember = IntPtr.Zero; stgm.tymed = TYMED.TYMED_ENHMF; pdo.GetData(ref fetc, out stgm); var hemf = GDI32.CopyEnhMetaFile(stgm.unionmember, emfOutputFileName); storage.Commit((int)OLE32.STGC.STGC_DEFAULT); pOle.Close(0); GDI32.DeleteEnhMetaFile(stgm.unionmember); GDI32.DeleteEnhMetaFile(hemf); }

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SQL SERVER – Fix : Error 3623 – An invalid floating point operation occurred

- by pinaldave

Going back in time, I always had a problem with mathematics. It was a great subject and I loved it a lot but I only mastered it after practices a lot. I learned that mathematics problems should be addressed systematically and being verbose is not a trick, I learned to solve any problem. Recently one of reader sent me an email with the title “Mathematics problem – please help!” and I was a bit scared. I was good at mathematics but not the best. When I opened the email I was relieved as it was Mathematics problem with SQL Server. My friend received following error while working with SQL Server. Msg 3623, Level 16, State 1, Line 1 An invalid floating point operation occurred. The reasons for the error is simply that invalid usage of the mathematical function is attempted. Let me give you a few examples of the same. SELECT SQRT(-5); SELECT ACOS(-3); SELECT LOG(-9); If you run any of the above functions they will give you an error related to invalid floating point. Honestly there is no workaround except passing the function appropriate values. SQRT of a negative number will give you result in real numbers which is not supported at this point of time as well LOG of a negative number is not possible (because logarithm is the inverse function of an exponential function and the exponential function is NEVER negative). When I send above reply to my friend he did understand that he was passing incorrect value to the function. As mentioned earlier the only way to fix this issue is finding incorrect value and avoid passing it to the function. Every mathematics function is different and there is not a single solution to identify erroneous value passed. If you are facing this error and not able to figure out the solution. Post a comment and I will do my best to figure out the solution. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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