1 files changed, 124 insertions, 0 deletions
diff --git a/gsl-1.9/randist/shuffle.c b/gsl-1.9/randist/shuffle.c
new file mode 100644
index 0000000..2ab34d7
--- /dev/null
+++ b/gsl-1.9/randist/shuffle.c
@@ -0,0 +1,124 @@
+/* randist/shuffle.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 James Theiler, Brian Gough
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <math.h>
+#include <gsl/gsl_rng.h>
+#include <gsl/gsl_randist.h>
+
+/* Inline swap and copy functions for moving objects around */
+
+static inline 
+void swap (void * base, size_t size, size_t i, size_t j)
+{
+  register char * a = size * i + (char *) base ;
+  register char * b = size * j + (char *) base ;
+  register size_t s = size ;
+
+  if (i == j)
+    return ;
+  
+  do                                            
+    {                                           
+      char tmp = *a;                            
+      *a++ = *b;                                
+      *b++ = tmp;                               
+    } 
+  while (--s > 0);                              
+}
+
+static inline void 
+copy (void * dest, size_t i, void * src, size_t j, size_t size)
+{
+  register char * a = size * i + (char *) dest ;
+  register char * b = size * j + (char *) src ;
+  register size_t s = size ;
+  
+  do                                            
+    {                                           
+      *a++ = *b++;                              
+    } 
+  while (--s > 0);                              
+}
+
+/* Randomly permute (shuffle) N indices
+
+   Supply an array x[N] with nmemb members, each of size size and on
+   return it will be shuffled into a random order.  The algorithm is
+   from Knuth, SemiNumerical Algorithms, v2, p139, who cites Moses and
+   Oakford, and Durstenfeld */
+
+void
+gsl_ran_shuffle (const gsl_rng * r, void * base, size_t n, size_t size)
+{
+  size_t i ;
+
+  for (i = n - 1; i > 0; i--)
+    {
+      size_t j = gsl_rng_uniform_int(r, i+1); /* originally (i + 1) * gsl_rng_uniform (r) */
+
+      swap (base, size, i, j) ;
+    }
+}
+
+int
+gsl_ran_choose (const gsl_rng * r, void * dest, size_t k, void * src, 
+                 size_t n, size_t size)
+{
+  size_t i, j = 0;
+
+  /* Choose k out of n items, return an array x[] of the k items.
+     These items will prevserve the relative order of the original
+     input -- you can use shuffle() to randomize the output if you
+     wish */
+
+  if (k > n)
+    {
+      GSL_ERROR ("k is greater than n, cannot sample more than n items",
+                 GSL_EINVAL) ;
+    }
+
+  for (i = 0; i < n && j < k; i++)
+    {
+      if ((n - i) * gsl_rng_uniform (r) < k - j)
+        {
+          copy (dest, j, src, i, size) ;
+          j++ ;
+        }
+    }
+
+  return GSL_SUCCESS;
+}
+
+void
+gsl_ran_sample (const gsl_rng * r, void * dest, size_t k, void * src, 
+                size_t n, size_t size)
+{
+  size_t i, j = 0;
+
+  /* Choose k out of n items, with replacement */
+
+  for (i = 0; i < k; i++)
+    {
+      j = gsl_rng_uniform_int (r, n);  /* originally n * gsl_rng_uniform (r) */
+
+      copy (dest, i, src, j, size) ;
+    }
+}