165 The term codec originates from the words compression/decompression (amus- ingly, the abbreviation is in a sense a form of compression). Popular codecs perform such functions as compressing and decompressing arbitrary data (e.g., ZIP, RAR), image-specific data (e.g., GIF, JPEG), or audio data (e.g., MP3, AIFF). Over time, the term codec has grown to include a wide variety of data translations, not all of which are useful for compression and decompression but instead serve other functions such as security, data transmission, or even spell-checking. While the JDK offers a variety of built-in handlers for dealing with popular compression formats such as ZIP, GIF, and JPG, the ApacheCommons Codec project fills in other gaps in functionality.
Given that they are essential to so many applications, all modern programming languages include special features for working with strings. Unfortunately, C++ complicates the issue by defining two different string types: an older style inherited from C and a more sophisticated string library that supports the object-oriented paradigm. To minimize confusion, this text uses the string library wherever possible, and you should—for the most part—feel free to ignore the fact that two string models exist. The times when that complexity raises its ugly head are outlined in Chapter 3, which covers the string library in more detail. For the moment, you can simply imagine that C++ offers a built-in data type called string whose domain is the set of all sequences of characters. You can declare variables of type string and pass string values back and forth between functions as arguments and results.
I still remember the first game programming book I ever read. By Dave Roberts, it was entitled PC Game Programming Explorer, and it demonstrated game programming with a game called Alien Alley. This was actually a neat game, especially for one intended as a book example: its graphics were smooth, the artwork was top-notch, and it ran well on my rather underpowered system. It would be easy for me to write such a game today, even in a matter of a few hours. But to a neophyte game programmer, it seemed a towering monolith. Back in the days of DOS-based gaming, programmers generally wrote games by issuing commands directly to the computer’s hardware. There were only a few popular types of sound cards on the market, and many were at least partially compatible with Creative Labs’ Sound Blaster. Input devices were trivial to program: accessing the mouse required only a few assembly language instructions (interrupt 33h, for those who remember), reading the joystick’s position was a matter of a dozen lines of code, and there were several easy ways to collect keyboard input. Video programming was the hardest part of game development at the time: Although nearly every computer had a
Most familiar programming languages, such as C or Java, are based on an imperative model of computation. Programs are thought of as specifying a sequence of commands that modify the memory of the computer. Each step of execution examines the current contents of memory, performs a simple computation, modifies the memory, and continues with the next instruction. The individual commands are executed for their effect on the memory (which we may take to include both the internal memory and registers and the external input/output devices). The progress of the com- putation is controlled by evaluation of expressions, such as boolean tests or arithmetic operations, that are executed for their value. Conditional commands branch according to the value of some expression. Many lan- guages maintain a distinction between expressions and commands, but often (in C, for example) expressions may also modify the memory, so that even expression evaluation has an effect.
The transfer of order between the different sensor mechanisms can be conscious or subconscious. One of more striking examples of subconscious transfer is given by Leontiev’s experiments [198, pp. 193–218] on training tone-deaf adults to distinguish the pitches of sounds by developing a correlation between pitch and muscular tension. Interestingly, visual perception played the role of interme- diary: the subjects had to pull a lever and equalize two gauges, one for pitch and another for the force applied. After some training of that kind, subjects attained a reasonable ability to recognize pitch even without gauges and levers. Their test performance deterio- rated, however, when the devious experimenter engaged subjects’ hands (or feet, if, in the training period, the lever was pushed by foot) in some activity. This example is even more puzzling because my applied mathematics colleagues told me that the sound recep- tors in our inner ear are actually doing, at the hardware level, a Fourier transform . At what point do the brains of tonally chal- lenged people start to ignore hardware readings?
x = ¯ a + t~u (and the equations (2)) are said to be normal . To normalize an equation of a line means to replace ~u by ~u/ | ~u | . Since c may also be negative, the line (1) does not change if we replace ~u by − ~u; thus the direction of a line is not uniquely determined: we always have two choices of the unit vector ~u. If, however, a particular ~u is prescribed in advance, we speak of a directed line. The coordinates of the direction vector ~u (or any of its scalar multiples c~u) are called a set of n direction numbers for the line (1); of course, there are infinitely many such sets corresponding to different values of c. In particular, the direction cosines of ~u (i.e., the components of the unit vector ~u/ | ~u | ) are called a set of direction cosines of the line. (There are precisely two such sets, namely the direction cosines of ~u and those of − ~u.)
If you want to implement this method in Java, it would probably be best to use a longer name than the single letter C used in mathematics. The one-character name might well cause confusion, if for no other reason than that the fact that its name is uppercase suggests a constant—possibly the speed of light. As a general rule, method names used in this text tend to be longer and more expressive than variable names. Method calls often appear in parts of the program that are far removed from the point at which those methods are defined. Since the definition may be hard to locate in a large program, it is best to choose a method name that conveys enough information about the method so that the reader does not need to look up the definition. Local variables, on the other hand, are used only within the body of a single method, and it is therefore easier to keep track of what they mean. In the interest of having the name of the combinations method make sense immediately when anyone looks at it, we will use the name combinations as the
To a request for a third solution the system will reply no (no more large countries). To write or understand Prolog programs, one has to think not only about their meaning as specifications, but also about Prolog’s search strategy. In that sense, Prolog is not fully declarative; it has an “operational semantics.” Answer set programming (ASP)—the form of logic programming described in this book—is closer to the ideal of declarativism. ASP became possible after the invention of the concept of a stable model and the creation of software systems that generate stable models. These systems are called answer set solvers, and their operation is described in many articles, dissertations, and books. But if your goal is to use answer set solvers, rather than design a new system of this kind, then you do not need to know much about how they operate. This book, in fact, will tell you almost nothing about what happens “under the hood.” (Section 3.4 and a passage in Section 2.8 are the only places where the operation of an answer set solver is discussed in any detail.) Answer set programming has no operational semantics.
In an earlier episode of this series, we have covered how to use the Email Service of GAEJ to send out emails from your application. At that point in time, we were using version 1.2.5 of the AppEngine SDK. That version did not provide support for handling incoming email. Since then a newer version of the AppEngine SDK for Java 1.2.6 has been released. And one of the nice features of this new release is support for incoming email in your application. What it means is that anyone can send an email to your GAEJ hosted application, it can receive an email and then you can process and perform some business logic with that as required.
To the extent that there seems to be something of an Artinian condition (no in- finite descending chain) on natural language constructions, we may want to inquire whether there is a Noetherian condition (no infinite ascending chain) as well. A con- struction whose head is some lexical category c is said to be a projection of c: the idea is that we obtain more and more complex constructions by successively adjoin- ing more and more material to the head lexical entry. Can this process terminate in some sense? Linguistics has traditionally recognized phrases as maximal projections (i.e. as constructions that can no longer be extended in nontrivial ways). The most important example is the noun phrase, which is effectively closed off from further development by a determiner or quantifier. Once this is in place, there is no further adjective, numeral, or other modifier that can be added from the left (compare *three the books, *three every books to the three books, every three books) and only relative clauses are possible from the right (the three books that I saw yesterday). Once such a that-clause is in place, again there is no room for different kinds of modifications. Further relative clauses are still possible (the three books that I saw yesterday that you bought today), but no other kind of element is. Other notable examples include the verb phrase (VP), the prepositional phrase (PP), the adjectival phrase (AP), and the adverbial phrase (AdvP) – since this covers all major categories, it is commonly assumed that every construction is part of a maximal (phrasal) construction that can be further extended only by the trivial means of coordination.
During this phase, JSF asks container/application server to render the page if the application is using JSP pages. For initial request, the components represented on the page will be added to the component tree as JSP container executes the page. If this is not an initial request, the component tree is already built so components need not be added again. In either case, the components will render themselves as the JSP container/Application server traverses the tags in the page.
Scala class types being relatively expensive to create, the type construc- tor also serves as a cache of all instantiations of itself. This cache is imple- mented as a purely functional red-black tree , and a reference points to its root. By updating this reference atomically, it is possible to manage this cache efficiently, without locking and in a thread-safe manner. Atomic update of the root can be easily achieved with the AtomicReference class of Java 5. For compatibility, the current implementation uses locks, but switching to a lock-free implementation is a matter of changing a single line in the code.
Jeffrey Oldham received a bachelor of arts degree in computer science from Rice University in 1991. After working at the Center for Research on Parallel Computation, he obtained a doctor of philoso- phy degree from Stanford in 2000. His research interests center on algorithm engineering, concentrating on flow and other combinator- ial algorithms. He works on GCC and scientific computing software. Alex Samuel graduated from Harvard in 1995 with a degree in physics. He worked as a software engineer at BBN before returning to study physics at Caltech and the Stanford Linear Accelerator Center. Alex administers the Software Carpentry project and works on various other projects, such as optimizations in GCC.
Java APIs are libraries of compiled code that you can use in your programs. They enable you to add ready-made and customizable functionality to save you programming time. The simple program in this lesson uses a Java API to print a line of text to the console. The printing capability is provided in the API ready for you to use. You supply the text to be printed. Figure 1 shows the Java platform architecture. The JVM sits on top of your native operating system. Your program sits on top of the JVM and calls compiled code from the API libraries that live within the JVM.
This tutorial is designed for Software Professionals who are willing to learn Pascal Programming Language in simple and easy steps. This tutorial will give you great understanding on Pascal Programming concepts, and after completing this tutorial, you will be at intermediate level of expertise from where you can take yourself to higher level of expertise.
Purpose of this book. This short treatise is intended to serve as a text for a freshman-level college course that, among other things, addresses the issues mentioned above. The book investigates interrelationships between mathe- matics and music. It reviews some background concepts in both subjects as they are encountered. Along the way, the reader will hopefully augment his/her knowledge of both mathematics and music. The two will be discussed and developed side by side, their languages intermingled and unified, the goal being to break down the dyslexia that inhibits their mental amalgamation and to encourage the analytic, quantitative, artistic, and emotional aspects of the mind to work together in the creative process. Musical and mathe- matical notions are brought together, such as scales/modular arithmetic, oc- tave identification/equivalence relation, intervals/logarithms, equal temper- ament/exponents, overtones/integers, tone/trigonometry, timbre/harmonic analysis, tuning/rationality. When possible, discussions of musical and math- ematical notions are directly interwoven. Occasionally the discourse dwells for a while on one subject and not the other, but eventually the connection is brought to bear. Thus you will find in this treatise an integrative treatment of the two subjects.
In particular, Java is safe (but native/unsafe code can be called), C# is not quite safe (safe except where the keyword unsafe is used, or when native code is called), Ada is unsafe, while C and C++ are clearly unsafe. Every language must permit unsafe code to be called, otherwise device drivers could not be used. You may consider it as a deficiency that neither viruses nor device drivers can be written in Java; some implementation has to be done in some other language. One could also consider it as an advantage; hardware access (which will not be portable anyway) has to be written well separated from the rest of the application. Those (usually small) pieces of software also have to be more thoroughly debugged since a programming error could crash the entire system without exception handling of system shutdown working, opposed to safe programs which terminates in a controlled way with supervisory functions and recovery systems still running. We use a Java-based approach to embedded systems programming since we need to trust their behavior.