Dr. Dobb's Journal - August 2008 - (Page 33)

Instantly Search Terabytes of Text r(t) = F•P, 0≤t≤1 where F =[F1 F2 F3 F4], and F1 = 1/2*cos(1/2πt)(cos(1/2πt)–1) F2 = 1/2*sin(1/2πt)(sin(1/2πt)+1) F3 = 1/2*cos(1/2πt)(cos(1/2πt)+1) F4 = 1/2*sin(1/2πt)(sin(1/2πt)–1) and P = | | | | P1 P2 P3 P4 | | | | which are the four control points of the curve segment r(t). N dozens of indexed, unindexed, fielded data and full-text search options (including Unicode support for hundreds of international languages) N file parsers / converters for hit-highlighted display of all popular file types N Spider supports static and dynamic web data; highlights hits while displaying links, formatting and images intact N API supports .NET, C++, Java, databases, etc. New .NET Spider API Figure 4: Equations that define the interpolating TSpline. such that segment i is denoted by points Pi–1, Pi, Pi+1, Pi+2; see Figure 6(a). The end segments are specified by doubling up the endpoints such as for the first segment: P1, P1, P2, P3. A TSpline-based ellipse is formed from a set of control points in a rectangular formation denoted by P1, P2, P3, P4. Each ellipse segment is derived from the control points in a round-robin scheme: P4 ,P1, P2, P3 for segment 1, P1, P2, P3, P4 for segment 2, and so on; see Figure 6(b). Since the TSpline is defined by a periodic basis function, you can dispense with defining the ellipse as a piecewise function and simply render all four quadrants of the ellipse by choosing one of the four curve segment configurations and iterating over the interval of [0,4] rather than in four times over [0,1]. This is a cleaner, more efficient implementation scheme than piecewise rendering. This functionality has been subclassed off of the VectorEllipse class as VectorEllipse4 (available online). Think of splines as a means used to mathematically “connect the dots” with a smooth curve h Spider Desktop wit h Spider Network wit CD/DVDs Publish for ider Web with Sp Win & .NET Engine for Linux Engine for New 64-bit The Smart Choice for Text Retrieval ® since 1991 N “Bottom line: dtSearch manages a Demo Program The demo program, specified by the EllipseDemo class (Listing One, available online; see “Resource Center,” page 5), is a framework subclassed from the Java Frame class and derived from the paint program in Steve Holzner’s book Java After Hours: 10 Projects You’ll Never Do at Work. Each function is selected from a drop-down menu called Draw. The Freehand Drawing function lets users draw a freeform curve against which to test ellipse-fitting using the two methods. It simply leaves a line following the path of the mouse when dragged across the drawing space and needs no further explanation. terabyte of text in a single index and returns results in less than a second” – InfoWorld N “For combing through large amounts of data,” dtSearch “leads the market” – Network Computing N dtSearch “covers all data sources powerful Web-based engines”– eWEEK N dtSearch “searches at blazing speeds” – Computer Reseller News Test Center See www.dtsearch.com for hundreds more reviews, and hundreds of developer case studies Contact dtSearch for fully-functional evaluations 1-800-IT-FINDS www.dtsearch.com August 2008 l www.ddj.com l Dr. Dobb’s Journal 33 http://www.dtsearch.com http://www.dtsearch.com http://www.dtsearch.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - August 2008

Dr. Dobb's Journal - August 2008 Contents Friday Night Fish Fry Alia Vox Developer Diaries Developer’s Notebook A Conversation with Christos Papadimitriou OpenGL and Mobile Devices: Round 2 Ellipse Specification Using Vectors Embed Custom GUIs in WPF Building RIAs on J2EE Foundations Disentangling Concepts in Object-Oriented Systems The Agile Edge Effective Concurrency Swaine’s Flames

Dr. Dobb's Journal - August 2008

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