Printer-friendly version As we'll soon see, the confidence interval for the ratio of two variances requires the use of the probability distribution known as the F-distribution. So, let's spend a few minutes learning the definition and characteristics of the F-distribution. If U and V are independent chi-square random variables with r1 and r2 degrees of freedom, respectively, then: Characteristics of the F-Distribution 1 F-distributions are generally skewed.
Programming the WshNetwork Object Example: Scripting Internet Explorer In Appendix C, "Automating Windows XP with Batch Files," you learn how to tame the command prompt by creating batch files—small, executable text files that run one or more commands.
You'll see that with a little ingenuity and a dash of guile, it's possible to make batch files perform some interesting and useful tasks.
Indeed, for many years, batch files were the only way to automate certain kinds of tasks. Unfortunately, the batch file world is relentlessly command-line—oriented. So, with the exception of being able to launch Windows programs, batch files remain ignorant of the larger Windows universe.
If you're looking to automate a wider variety of tasks in Windows, you need to supplement your batch file knowledge with scripts that can deal with the Registry, shortcuts, files, and network drives, and that can even interact with Windows programs via Automation.
This chapter introduces you to the Windows Script Host, shows you how to execute scripts, and runs through the various elements in the Windows Script Host object model. Your Host for Today's Script As you might know, Internet Explorer is really just an empty container application that's designed to host different data formats, including ActiveX controls, various file formats such as Microsoft Word documents and Microsoft Excel worksheetsand several ActiveX scripting engines.
A scripting engine is a dynamic link library DLL that provides programmatic support for a particular scripting language. Internet Explorer supports two such scripting engines: This enables web programmers to write small programs—scripts—that interact with the user, control the browser, set cookies, open and close windows, and more.
Although these scripting engines don't offer full-blown programmability you can't compile scripts, for examplethey do offer modern programming structures such as loops, conditionals, variables, objects, and more. In other words, they're a huge leap beyond what a mere batch file can do.
The Windows Script Host is also a container application, albeit a scaled-down application in that its only purpose in life is to host scripting engines. However, Microsoft designed the Windows Script Host to be a universal host that can support any ActiveX-based scripting engine.
Therefore, there are also third-party vendors offering scripting engines for languages such as Perl, Tcl, and Rexx.
The key difference between Internet Explorer's script hosting and the Windows Script Host is the environment in which the scripts run. Internet Explorer scripts are web page—based, so they control and interact with either the web page or the web browser.
The Windows Script Host runs scripts within the Windows Vista shell or from the command prompt, so you use these scripts to control various aspects of Windows. Here's a sampling of the things you can do: After all, you wouldn't want to load something that's the size of Internet Explorer each time you need to run a simple script.
That's not a problem because, as I've said, the Windows Script Host does nothing but host scripting engines, so it has much less memory overhead than Internet Explorer. That means that your scripts run quickly. For power users looking for a Windows-based batch language, the Windows Script Host is a welcome tool.
For a basic calculator, you might want to define this as an int (actually the default), float, or double. If you want to exchange text, set this as a character pointer or array. Delayed environment variable expansion allows you to use a different character (the exclamation mark) to expand environment variables at execution time.
If delayed variable expansion is enabled, the above examples could be written as follows to work as intended. File I/O.
In NetLogo, there is a set of primitives that give you the power to interact with outside files. They all begin with the prefix file There are two main modes when dealing with files: reading and writing.
One of the primary ways that we will need to interact with an F-distribution is by needing to know either (1) an F-value, or (2) the probabilities associated with an F-random variable, in order to complete a statistical analysis.
Write a program to exchange numbers using pointers.
Write a shell program to exchange the values of two variables ; Write a shell program to exchange the values of two variables; Program to sort a list in alphabatic order using pointers;. If you access the same memory subsequently it’s better to use a temporary variable in C, so the compiler can make register optimizations (put it in registers, calculate on it, then put it in memory).
In this case it would work, since x and y would be on two registers or temporary variables.