1 files changed, 101 insertions, 0 deletions
diff --git a/gsl-1.9/sort/sortind.c b/gsl-1.9/sort/sortind.c
new file mode 100644
index 0000000..52cdc47
--- /dev/null
+++ b/gsl-1.9/sort/sortind.c
@@ -0,0 +1,101 @@
+/*
+ * Implement Heap sort -- direct and indirect sorting
+ * Based on descriptions in Sedgewick "Algorithms in C"
+ * Copyright (C) 1999  Thomas Walter
+ *
+ * 18 February 2000: Modified for GSL by Brian Gough
+ *
+ * This 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, or (at your option) any
+ * later version.
+ *
+ * This source 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.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <gsl/gsl_heapsort.h>
+
+static inline void downheap (size_t * p, const void *data, const size_t size, const size_t N, size_t k, gsl_comparison_fn_t compare);
+
+#define CMP(data,size,j,k) (compare((const char *)(data) + (size) * (j), (const char *)(data) + (size) * (k)))
+
+static inline void
+downheap (size_t * p, const void *data, const size_t size, const size_t N, size_t k, gsl_comparison_fn_t compare)
+{
+  const size_t pki = p[k];
+
+  while (k <= N / 2)
+    {
+      size_t j = 2 * k;
+
+      if (j < N && CMP (data, size, p[j], p[j + 1]) < 0)
+        {
+          j++;
+        }
+
+      if (CMP (data, size, pki, p[j]) >= 0)
+        {
+          break;
+        }
+
+      p[k] = p[j];
+
+      k = j;
+    }
+
+  p[k] = pki;
+}
+
+int
+gsl_heapsort_index (size_t * p, const void *data, size_t count, size_t size, gsl_comparison_fn_t compare)
+{
+  /* Sort the array in ascending order. This is a true inplace
+     algorithm with N log N operations. Worst case (an already sorted
+     array) is something like 20% slower */
+
+  size_t i, k, N;
+
+  if (count == 0)
+    {
+      return GSL_SUCCESS;       /* No data to sort */
+    }
+
+  for (i = 0; i < count; i++)
+    {
+      p[i] = i ;                /* set permutation to identity */
+    }
+
+  /* We have n_data elements, last element is at 'n_data-1', first at
+     '0' Set N to the last element number. */
+
+  N = count - 1;
+
+  k = N / 2;
+  k++;                          /* Compensate the first use of 'k--' */
+  do
+    {
+      k--;
+      downheap (p, data, size, N, k, compare);
+    }
+  while (k > 0);
+
+  while (N > 0)
+    {
+      /* first swap the elements */
+      size_t tmp = p[0];
+      p[0] = p[N];
+      p[N] = tmp;
+
+      /* then process the heap */
+      N--;
+
+      downheap (p, data, size, N, 0, compare);
+    }
+
+  return GSL_SUCCESS;
+}