NAG Library Function Document

nag_rngs_permute (g05nac)

exceeds the cycle length of nag_rngs_basic (g05kac) for any valid value of igen. For practical purposes this is irrelevant, as the time necessary to generate all possible permutations is many millenia.

One of the initialization functions nag_rngs_init_repeatable (g05kbc) (for a repeatable sequence if computed sequentially) or nag_rngs_init_nonrepeatable (g05kcc) (for a non-repeatable sequence) must be called prior to the first call to nag_rngs_permute (g05nac).

4 References

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

5 Arguments

1: index[n] – IntegerInput/Output: On entry: the $n$ integer values to be permuted.

On exit: the $n$ permuted integer values.
2: n – IntegerInput: On entry: the number of values to be permuted.
Constraint: $n \geq 1$ .
3: igen – IntegerInput: On entry: must contain the identification number for the generator to be used to return a pseudorandom number and should remain unchanged following initialization by a prior call to nag_rngs_init_repeatable (g05kbc) or nag_rngs_init_nonrepeatable (g05kcc).
4: iseed[ $4$ ] – IntegerCommunication Array: On entry: contains values which define the current state of the selected generator.
On exit: contains updated values defining the new state of the selected generator.
5: fail – NagError *Input/Output: The NAG error argument (see Section 3.6 in the Essential Introduction).

6 Error Indicators and Warnings

NE_BAD_PARAM: On entry, argument $〈value〉$ had an illegal value.
NE_INT: On entry, $n = 〈value〉$ .
Constraint: $n \geq 1$ .
NE_INTERNAL_ERROR: 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 for assistance.

7 Accuracy

Not applicable.

8 Further Comments

None.

9 Example

In the example program a vector containing the first eight positive integers in ascending order is permuted by a call to nag_rngs_permute (g05nac) and the permutation is printed. This is repeated a total of ten times, after initialization by nag_rngs_init_repeatable (g05kbc).