“extension”的概念、定义、翻译、参考文献-科学参考

extension

Mathematics

The difference x−l between the actual length x of a string or spring and its natural length l. The extension of a spring is negative when the spring is compressed.

Computer

1. The part of a file name that indicates the type of file. For example, in the file ‘document.txt’, the ‘txt’ is the extension, indicating that the file is a text file. A large number of such standard extensions exist. A list of common examples is given in the Appendices.
2. An add-on program that provides additional features to an existing program (for example, a QuarkXpress extension for indexing).
3. (of a source in coding theory). The process of encoding several symbols at a time, or the results thereof. If the symbols of a q-ary information source are taken r at a time, and the words of length r are treated (e.g. encoded) as if they were themselves symbols of an alphabet of size q^r, then this compound source is called the rth extension of the original source. See also source coding theorem.

Geology and Earth Sciences

A measure of the change in length of a line from its initial unit length. Extension may be positive (elongation) or negative (shortening), depending on whether the length of the line increases or decreases. The simplest type of extension (e) is calculated from: e = (L_f − L₀)/L₀, where L_f is the final length and L₀ the original unit length.

单词	extension
释义	extension Mathematics The difference x−l between the actual length x of a string or spring and its natural length l. The extension of a spring is negative when the spring is compressed. Computer 1. The part of a file name that indicates the type of file. For example, in the file ‘document.txt’, the ‘txt’ is the extension, indicating that the file is a text file. A large number of such standard extensions exist. A list of common examples is given in the Appendices. 2. An add-on program that provides additional features to an existing program (for example, a QuarkXpress extension for indexing). 3. (of a source in coding theory). The process of encoding several symbols at a time, or the results thereof. If the symbols of a q-ary information source are taken r at a time, and the words of length r are treated (e.g. encoded) as if they were themselves symbols of an alphabet of size q^r, then this compound source is called the rth extension of the original source. See also source coding theorem. Geology and Earth Sciences A measure of the change in length of a line from its initial unit length. Extension may be positive (elongation) or negative (shortening), depending on whether the length of the line increases or decreases. The simplest type of extension (e) is calculated from: e = (L_f − L₀)/L₀, where L_f is the final length and L₀ the original unit length.
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