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Functions EvaluateAt, EvaluateAtPattern, PositionMin, PositionMax, Cases, Select, Position

Ted Ersek
Organization: Naval Air Warfare Center, Aircraft Division
URL: http://www.verbeia.com/mathematica/
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The conventions for specifying sequences and levels are documented in sections A.3.5 and A.3.6 respectively in The Mathematica Book. In those sections the documentation explains how negative integers are used in sequence and level specifications. However the built in versions of Cases, Select, Position, StringPosition do not allow use of negative integers for sequence or level specification. This package enhances those functions to ensure they treat negative numbers as described in section A.3.5 and A.3.6.

The package also defines new functions PositionMin, PositionMax, EvaluateAt, EvaluateAtPattern. In addition the package enhances Position so it can return 'extended positions' which are needed to give the position of (a+c) in f[1+a+b+c]. The functions MapAt, ReplacePart, Extract and EvaluateAt can work with extended positions. For an explanation of installing the package and demonstration of all enhancements see the notebook (SelectingElementsExamples.nb).

*Wolfram Technology > Programming

Element, Evaluate, Evaluation, Min, Max, String, Cases, Select, Position
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SelectingElements.m (21.9 KB) - Mathematica package [for Mathematica 5.0]
SelectingElementsTutorial.nb (41.4 KB) - Mathematica notebook [for Mathematica 5.0]