Topic: index sequence for array access

topics > computer science > data > Group: sequences

access to components of a data object
data record
concurrency control by sequencers
for loop
ordered data types
range data type
sequence generators


An index sequence or induction variable is a sub-range of the integers usually used for sequential array access. An element step of '1' is most frequent but other steps can be used to access an array slice. Multiple steps may be included, e.g., '1 (.2) 2 (1) 5'. The index sequence may be used as a basis for accessing other sequences. (cbb 5/80)

An index sequence may be created explicitly. An iterator needs a method to indicate termination and the next element. Recording the last iteration value (tracer) and whether or not the loop completed (halter) is helpful. (cbb 1/90)

Subtopic: index set -- subset of ordinals up

Quote: a Modula-3 array consists of elements of the same size and type, and an index by values of an ordinal type [»cardL_1991]
Quote: an index set indicates members of a vector; can access in parallel or one at a time [»perrRH10_1979]
Quote: a parallel variable represents a sequence of integer numbers; e.g., oddseq= 1:(2)31 [»perrRH10_1979]

Subtopic: partitioned index up

Quote: locality-aware matrix indexing by partitioning the index into column bits and row bits; problem of software and hardware support [»adamMD5_2006]

Subtopic: induction/index variables up

Quote: a program includes global, local, and induction variables; only local and induction (the bound variables) may use shared storage; [»goldHH_1948, OK]
QuoteRef: goldHH_1948 ;;92 substitution boxes for changing bound induction variables (eg setting i to i+1

Subtopic: iterator up

Quote: a controlled iterator accesses the next element only if 'promote i' was executed [»berzAT_1980]
Quote: an iteration variable can have a halter defined that becomes true on the last loop [»berzAT_1980]
Quote: an iteration loop exits when all iterators are exhausted; tracers (loop index) and halters (last iteration) remain valid [»berzAT_1980]
Quote: the tracer (index variable) of an exhausted iterator accesses the last element after loop exit [»berzAT_1980]

Subtopic: examples of index sequence up

QuoteRef: hehnEC7_1975 ;;8 sequences by a by b to c or A to C
QuoteRef: morrJH8_1972 ;;761 ranges 0 =< a =< 10 from 0 to 10 by succ(a) k >= 1 as n times from 1 -> 1+(n-1)
QuoteRef: wileDS11_1973 ;;41 positive integers are 0/(+1*); ==<1;2;3;4;5...>
QuoteRef: hogbD10_1971 ;;19 index list by 1***8 (i.e. 1,2,3...8). reference to box by *row,col*
QuoteRef: sammJE_1969 ;;131 Laning and Ziesler '54: loops by v=1(.2)2(1)5 is 1,1.2,1.4,1.6,1.8,2, 3,4,5
QuoteRef: wellMB4_1964 ;;433 j~k is all x bounded by j and k i.e. [j,k)

Related Topics up

Topic: access to components of a data object (4 items)
Topic: arrays (58 items)
Topic: data record (57 items)
Topic: concurrency control by sequencers (27 items)
Topic: for loop (18 items)
Topic: iterator (13 items)
Topic: ordered data types (8 items)
Topic: range data type (17 items)
Topic: sequence generators
(16 items)

Updated barberCB 7/04
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