# pattern matching

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Related to pattern matching: Pattern recognition

## pattern matching

(1)
A function is defined to take arguments of a particular type, form or value. When applying the function to its actual arguments it is necessary to match the type, form or value of the actual arguments against the formal arguments in some definition. For example, the function

length [] = 0 length (x:xs) = 1 + length xs

uses pattern matching in its argument to distinguish a null list from a non-null one.

There are well known algorithm for translating pattern matching into conditional expressions such as "if" or "case". E.g. the above function could be transformed to

length l = case l of [] -> 0 x:xs -> 1 : length xs

Pattern matching is usually performed in textual order though there are languages which match more specific patterns before less specific ones.

## pattern matching

(2)
Descriptive of a type of language or utility such as awk or Perl which is suited to searching for strings or patterns in input data, usually using some kind of regular expression.
References in periodicals archive ?
For pattern matching to predict this, though, you have to use good patterns.
The polymeric substrate was preheated in the laboratory oven at least 30 min at setting temperature to guarantee the temperature uniformity of the substrate for Pattern matching B.
We consider here the so-called permutation pattern matching problem (also sometimes referred to as the pattern involvement problem): Given two permutations [sigma] of size k and [pi] of size n, the problem is to decide whether [sigma] [??] [pi] (the problem is attributed to Wilf in [5]).
Rabin-karp Palmprint Pattern Matching (RPPM) method is used for improve the performance of palm print feature matching.
Note that this pattern matching is flexible enough to allow for some variation such as that which arises from the type of growth medium and growth phase the bacteria was in, while still providing consistent identification calls.
Case 2: If complete match is found then start KMP pattern matching method [1] form left to right.
After obtaining spatial patterns and direction patterns of vehicle trajectories, we conducted traffic abnormal behavior recognition based on mixed pattern matching, which contains the spatial patterns and direction patterns.
To construct an efficient inference engine, one of the most reasonable solutions is to implement an ECA engine by using pattern matching algorithm developed for production systems.
However, because comparisons require pattern matching processing, as with previous vein authentication technology, the process can be slow.
Many computer systems for deep packet inspection, especially intrusion detection systems, employ one or multiple pattern matching algorithms to search for signatures within the packet payload, which will be refered to as a text in this paper.

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