Topic:
arrays
Topic:
associative memory
Topic:
trees
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Summary
Sparse arrays are arrays with most elements zero or undefined. Instead of normal array implementations, they are implemented with explicitly stated indices in a tree, list, or associative memory. The data objects of the MUMPS medical information system are sparse arrays, allowing dynamic definition of the data base. In MUMPS, the array indices represent attributes of the data objects. Gehani (gahaN2_79) defines 'grids' which are regularly specified sparse arrays. They allow more efficient, but less flexible, implementations. (cbb 5/80)
Subtopic: sparse array 
| QuoteRef: mumps ;; global variables -- sparse arrays on disk, siblings chained together with links to sons. use of an entry implies the path to get to the entry.
| | QuoteRef: shawCJ_1963 ;;93 variable data structure -- sparse table with optional entries indexed by name.
| | QuoteRef: smitJW_1970 ;;227 allows sparse array declaration.
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Subtopic: sparse bit vector
| Quote: bit-counting algorithm based on frequency division; most efficient for sparse vectors [»berkS11_2000]
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Subtopic: grid -- array subset
| Quote: a grid is the union of some arrays minus the union of other arrays; e.g., GRID[1..20 PLUS 30..50] [»gahaN2_1979]
| | Quote: declare grid in terms of other coordinates; e.g., triangular grid by GRID[i in 1..100, 1..i] [»gahaN2_1979]
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Related Topics
Topic: arrays (58 items)
Topic: associative memory (5 items)
Topic: trees
(21 items)
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