Typesetting variable-sized curved symbols
Azzeddine Lazrek · 2003
The main goal of this contribution is to present a program that allows the com-position of variable-sized curved symbols such as those occurring in mathemat-ics. This application, called CurExt, extends the capabilities of the well-known system TEX designed by D. E. Knuth for typesetting. Big delimiters, such as brackets, or special curved symbols, such as the Arabic mathematical symbol of sum, can be built automatically according to the size and the shape of the con-cerned mathematical expression. CurExt will make it possible to stretch Arabic letters according to calligraphic rules in order to draw the kashida. It follows a useful tool for justifying texts written with Arabic alphabet. Unlike in Latin alphabet based writing, where the justication is done through inserting small blanks among characters, cursive writing lls in the space between characters with the kashida. The problem Variable-sized symbols Besides xed size symbols, such as characters of Latin alphabet in a given font or basic mathematical symbols (e.g., +, ¡), there are symbols with a context dependant size. Some mathematical symbols, such as delimiters or Arabic characters, are examples of these variable-sized symbols. The variation of size can concern: the width of the symbol, such as in: the various parts of some symbols (e.g.,E or,)). A horizontal stretching, according to the expression covered by the operator, is sometimes necessary; the kashida for some characters of the Arabic alphabet (e.g., , ) or certain Arabic mathematical symbols such as th-ose found in the abbreviations of usual fun-ctions (e.g., , , ) in mathematical expressions. The kashida , a small curve, is used to stretch some characters in order to cover the concerned mathematical expression or to break the line when the left margin is reached; some diacritics or accents (e.g., abc; abc; cabc; fabc;áabc;¡!abc; z}|{abc; abc|{z} or