Re: [Help-gsl] GSL Implementation of Quick Sort (or something better)

[Matthew Boulton]

Could I use the cmp() function as the compare function? For example:

qsort( v->data , v->size , sizeof(double) , int(*cmp)( array_index , 
array_data ) )

Kind Regards,

Matt

> why not use the qsort(3) function?
>
> if you have a gsl_vector *v:
>
> qsort(v->data, v->size, sizeof(double), &compare)
>
> where you would just have to write the compare function.
>
> On Thu, Aug 16, 2007 at 05:10:00PM +0100, Matthew Boulton wrote:
> > / Hello. I've got some quick sort code that is now reading in data from /
> > / GSl vectors, and so I was wondering if there is a GSL implementation of /
> > / the quick sort algorithm given below:/
> > / /
> > / --quick_sort.c/
> > / /
> > / #include "common.h"/
> > / /
> > / void quick_sort (DATA_TYPE *list, int *index, int n){/
> > / /
> > /  int i;/
> > /  void quick_sort_1();/
> > / /
> > /  for ( i = 0; i < n; i++ ) index [i]=i;/
> > /  quick_sort_1 ( list , index , 0 , n-1 );/
> > / /
> > /  return;/
> > / /
> > / }/
> > / /
> > / -- quick_sort_1.c/
> > / /
> > / #include "common.h"/
> > / /
> > / void quick_sort_1(DATA_TYPE *list, int *index, int left_end, int right_end)/
> > / /
> > / {/
> > / /
> > /  int i, j, temp;/
> > /  DATA_TYPE chosen;/
> > / /
> > /  chosen = list[ index[ (left_end + right_end) / 2 ] ];/
> > /  i = (left_end - 1);/
> > /  j = (right_end + 1);/
> > / /
> > /  for (;;)/
> > / /
> > /    {/
> > /  /
> > /    while (list [index[++i]] < chosen);/
> > /    while (list [index[--j]] > chosen);/
> > /   /
> > /    if (i < j)/
> > / /
> > /      {/
> > /     /
> > /         temp = index [j];/
> > /         index [j] = index [i];/
> > /         index [i] = temp;/
> > /     /
> > /      }/
> > / /
> > /    else if (i==j)/
> > / /
> > /      {/
> > / /
> > /      ++i;/
> > /      break;/
> > /   /
> > /      }/
> > /   /
> > /    else break;/
> > /  /
> > /  }/
> > / /
> > /  if (left_end < j)  quick_sort_1 (list, index, left_end, j);/
> > /  if (i < right_end) quick_sort_1 (list, index, i, right_end);/
> > / /
> > /  return;/
> > /   /
> > / }/
> > / /
> > / which looks like a fairly standard quick sort algorithm. If there is no /
> > / GSL quick sort algorithm, then would the GSL heapsort algorithm easily /
> > / take the place of the above quick sort  function?/
> > / /
> > / Kind Regards,/
> > / /
> > / Matt/
> > / /
> > / /
> > / /
> > / _______________________________________________/
> > / Help-gsl mailing list/
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> > / /