random_permutation
Generates a pseudorandom permutation.
Synopsis
#include <imsls.h>
int *imsls_random_permutation (int k, ..., 0)
Required Arguments
int k (Input)
Number of integers to be permuted.
Return Value
An array of length k containing the random permutation of the integers from 1 to k. To release this space, use imsls_free.
Synopsis with Optional Arguments
#include <imsls.h>
int *imsls_random_permutation (int k,
IMSLS_RETURN_USER, int ir[],
0)
Optional Arguments
IMSLS_RETURN_USER, int ir[] (Output)
User-supplied array of length k containing the random permutation of the integers from 1 to k.
Description
Function imsls_random_permutation generates a pseudorandom permutation of the integers from 1 to k. It begins by filling a vector of length k with the consecutive integers 1 to k. Then, with M initially equal to k, a random index J between 1 and M (inclusive) is generated. The element of the vector with the index M and the element with index J swap places in the vector. M is then decremented by 1 and the process repeated until M = 1.
Example
In this example, imsls_random_permutation is called to produce a pseudorandom permutation of the integers from 1 to 10.
#include <stdio.h>
#include <imsls.h>
int main()
{
int *ir, k = 10;
imsls_random_seed_set(123457);
ir = imsls_random_permutation(k, 0);
printf("Random permutation of the integers from 1 to 10\n");
imsls_i_write_matrix("", 1, k, ir,
IMSLS_NO_COL_LABELS, 0);
}
Output
Random permutation of the integers from 1 to 10
5 9 2 8 1 6 4 7 3 10