NAG Library Function Document
nag_rand_permute (g05ncc) performs a pseudorandom permutation of a vector of integers.
||nag_rand_permute (Integer indx,
nag_rand_permute (g05ncc) permutes the elements of an integer array without inspecting their values. Each of the possible permutations of the values may be regarded as being equally probable.
Even for modest values of it is theoretically impossible that all permutations may occur, as is likely to exceed the cycle length of any of the base generators. For practical purposes this is irrelevant, as the time necessary to generate all possible permutations is many millenia.
One of the initialization functions nag_rand_init_repeatable (g05kfc)
(for a repeatable sequence if computed sequentially) or nag_rand_init_nonrepeatable (g05kgc)
(for a non-repeatable sequence) must be called prior to the first call to nag_rand_permute (g05ncc).
Kendall M G and Stuart A (1969) The Advanced Theory of Statistics (Volume 1) (3rd Edition) Griffin
Knuth D E (1981) The Art of Computer Programming (Volume 2) (2nd Edition) Addison–Wesley
indx[n] – IntegerInput/Output
On entry: the integer values to be permuted.
On exit: the permuted integer values.
n – IntegerInput
On entry: the number of values to be permuted.
state – IntegerCommunication Array
, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument state
in the previous call to nag_rand_init_repeatable (g05kfc)
or nag_rand_init_nonrepeatable (g05kgc)
On entry: contains information on the selected base generator and its current state.
On exit: contains updated information on the state of the generator.
fail – NagError *Input/Output
The NAG error argument (see Section 3.6
in the Essential Introduction).
6 Error Indicators and Warnings
On entry, argument had an illegal value.
On entry, .
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG
On entry, state
vector has been corrupted or not initialized.
8 Parallelism and Performance
In the example program a vector containing the first eight positive integers in ascending order is permuted by a call to nag_rand_permute (g05ncc) and the permutation is printed. This is repeated a total of ten times, after initialization by nag_rand_init_repeatable (g05kfc)
10.1 Program Text
Program Text (g05ncce.c)
10.2 Program Data
10.3 Program Results
Program Results (g05ncce.r)