diff --git a/lib/Makefile b/lib/Makefile
index 0057b7c..ff55a71 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -1,5 +1,5 @@
 SHLIBS= libCosmoTool.so
-SOURCES= loadRamses.cpp yorick.cpp miniargs.cpp  fortran.cpp interpolate.cpp load_data.cpp powerSpectrum.cpp octTree.cpp
+SOURCES= loadRamses.cpp yorick.cpp miniargs.cpp  fortran.cpp interpolate.cpp load_data.cpp powerSpectrum.cpp octTree.cpp 
 LIBS= -lnetcdf_c++ -lnetcdf -lgsl -lgslcblas -lm
 
 include config.mk
diff --git a/src/kdtree_leaf.hpp b/src/kdtree_leaf.hpp
new file mode 100644
index 0000000..3a3a0b6
--- /dev/null
+++ b/src/kdtree_leaf.hpp
@@ -0,0 +1,105 @@
+#ifndef __LEAF_KDTREE_HPP
+#define __LEAF_KDTREE_HPP
+
+#include <cmath>
+#include "config.hpp"
+#include "bqueue.hpp"
+
+namespace CosmoTool {
+
+  template<int N, typename CType = ComputePrecision> 
+  struct KDLeafDef
+  {
+    typedef CType CoordType;
+    typedef float KDLeafCoordinates[N];
+  };
+  
+  template<int N, typename ValType, typename CType = ComputePrecision>
+  struct KDLeafCell
+  {
+    bool active;
+    ValType val;
+    typename KDLeafDef<N,CType>::KDLeafCoordinates coord;
+  };
+
+  class NotEnoughCells: public Exception
+  {
+  public:
+    NotEnoughCells() : Exception() {}
+    ~NotEnoughCells() throw () {}
+  };
+
+  template<int N, typename ValType, typename CType = ComputePrecision>
+  struct KDLeafTreeNode
+  {
+    bool leaf;
+    union {
+      KDLeafCell<N,ValType,CType> *value;
+      KDLeafTreeNode<N,ValType,CType> *children[2];
+    };
+    typename KDLeafDef<N,CType>::KDLeafCoordinates minBound, maxBound;
+#ifdef __KDLEAF_TREE_NUMNODES
+    uint32_t numNodes;
+#endif
+  };
+
+  template<int N, typename ValType, typename CType = ComputePrecision>
+  class KDLeafTree
+  {
+  public:
+    typedef typename KDLeafDef<N,CType>::CoordType CoordType;
+    typedef typename KDLeafDef<N>::KDLeafCoordinates coords;
+    typedef KDLeafCell<N,ValType,CType> Cell;
+    typedef KDLeafTreeNode<N,ValType,CType> Node;
+
+    KDLeafTree(Cell *cells, uint32_t Ncells);
+    ~KDLeafTree();
+
+    Node *getRoot() { return root; }
+
+    void optimize();
+
+    Node *getAllNodes() { return nodes; }
+    uint32_t getNumNodes() const { return lastNode; }
+
+    uint32_t countActives() const;
+
+    CoordType computeDistance(const Cell *cell, const coords& x) const;
+
+#ifdef __KDLEAF_TREE_NUMNODES
+    uint32_t getNumberInNode(const Node *n) const { return n->numNodes; }
+#else
+    uint32_t getNumberInNode(const Node *n) const {
+      if (n == 0) 
+        return 0;
+      return 1+getNumberInNode(n->children[0])+getNumberInNode(n->children[1]);
+    }
+#endif
+
+    double countInRange(CType sLo, CType sHi, Node *root1 = 0, Node *root2 = 0) const;
+
+  protected:
+    Node *nodes;
+    uint32_t numNodes, numCells;
+    uint32_t lastNode;
+
+    Node *root;
+    Cell **sortingHelper;
+
+    Node *buildTree(Cell **cell0,
+		    uint32_t NumCells,
+		    uint32_t depth,
+		    coords minBound,
+		    coords maxBound);
+    
+    double recursiveCountInRange(Node *na, Node *nb, CType sLo, CType sHi) const;
+  };
+
+  template<int N, typename T, typename CType>
+  uint32_t gatherActiveCells(KDLeafCell<N,T,CType> **cells, uint32_t numCells);
+
+};
+
+#include "kdtree_leaf.tcc"
+
+#endif
diff --git a/src/kdtree_leaf.tcc b/src/kdtree_leaf.tcc
new file mode 100644
index 0000000..704b488
--- /dev/null
+++ b/src/kdtree_leaf.tcc
@@ -0,0 +1,308 @@
+#include <cstring>
+#include <algorithm>
+#include <limits>
+#include <iostream>
+#include <cassert>
+
+namespace CosmoTool {
+
+  template<int N, typename ValType, typename CType>
+  class CellCompare
+  {
+  public:
+    CellCompare(int k)
+    {
+      rank = k;
+    }
+
+    bool operator()(const KDLeafCell<N,ValType,CType> *a, const KDLeafCell<N,ValType,CType> *b) const
+    {
+      return (a->coord[rank] < b->coord[rank]);
+    }
+  protected:
+    int rank;
+  };
+
+  template<int N, typename ValType, typename CType>
+  KDLeafTree<N,ValType,CType>::~KDLeafTree()
+  {
+  }
+
+  template<int N, typename ValType, typename CType>
+  KDLeafTree<N,ValType,CType>::KDLeafTree(Cell *cells, uint32_t Ncells)
+  {
+    numNodes = Ncells*3;
+    numCells = Ncells;
+    nodes = new Node[numNodes];
+
+    sortingHelper = new Cell *[Ncells];
+    for (uint32_t i = 0; i < Ncells; i++)
+	sortingHelper[i] = &cells[i];    
+
+    optimize();
+  }
+
+  template<int N, typename ValType, typename CType>
+  void KDLeafTree<N,ValType,CType>::optimize()
+  {
+    coords absoluteMin, absoluteMax;
+
+    std::cout << "Optimizing the tree..." << std::endl;
+    uint32_t activeCells = gatherActiveCells(sortingHelper, numCells);
+    std::cout << "  number of active cells = " << activeCells << std::endl;
+
+    lastNode = 0;
+    for (int i = 0; i < N; i++)
+      {
+	absoluteMin[i] = std::numeric_limits<typeof (absoluteMin[0])>::max();
+	absoluteMax[i] = -std::numeric_limits<typeof (absoluteMax[0])>::max();
+      }
+    // Find min and max corner
+    for (uint32_t i = 0; i < activeCells; i++)
+      {
+        KDLeafCell<N,ValType,CType> *cell = sortingHelper[i];
+
+        for (int k = 0; k < N; k++) {
+          if (cell->coord[k] < absoluteMin[k])
+            absoluteMin[k] = cell->coord[k];
+          if (cell->coord[k] > absoluteMax[k])
+            absoluteMax[k] = cell->coord[k];
+        }
+      }
+    
+    std::cout << "   rebuilding the tree..." << std::endl;
+    root = buildTree(sortingHelper, activeCells, 0, absoluteMin, absoluteMax);    
+    std::cout << "   done." << std::endl;
+  }
+
+  template<int N, typename ValType, typename CType>
+  uint32_t gatherActiveCells(KDLeafCell<N,ValType,CType> **cells,
+			     uint32_t Ncells)
+  {
+    uint32_t swapId = Ncells-1;
+    uint32_t i = 0;
+
+    while (!cells[swapId]->active && swapId > 0)
+      swapId--;
+
+    while (i < swapId)
+      {
+	if (!cells[i]->active)
+	  {
+	    std::swap(cells[i], cells[swapId]);
+	    while (!cells[swapId]->active && swapId > i)
+	      {
+		swapId--;
+	      }
+	  }
+	i++;
+      }
+    return swapId+1;
+  }
+
+  template<int N, typename ValType, typename CType>
+  KDLeafTreeNode<N,ValType,CType> *
+        KDLeafTree<N,ValType,CType>::buildTree(Cell **cell0,
+					       uint32_t Ncells,
+					       uint32_t depth,
+					       coords minBound,
+					       coords maxBound)
+  {
+    if (Ncells == 0)
+      return 0;
+
+    int axis = depth % N;
+    assert(lastNode != numNodes);
+    Node *node = &nodes[lastNode++];
+    uint32_t mid = Ncells/2;
+    coords tmpBound;
+    
+    // Isolate the environment
+    {
+      CellCompare<N,ValType,CType> compare(axis);
+      std::sort(cell0, cell0+Ncells, compare);
+    }
+
+    node->leaf = false;
+    memcpy(&node->minBound[0], &minBound[0], sizeof(coords));
+    memcpy(&node->maxBound[0], &maxBound[0], sizeof(coords));
+
+    if (Ncells == 1)
+      {
+	node->leaf = true;
+	node->value = *cell0;
+
+#ifdef __KDLEAF_TREE_NUMNODES
+	node->numNodes = 1;
+#endif
+	return node;
+      }
+
+    memcpy(tmpBound, maxBound, sizeof(coords));
+    tmpBound[axis] = (*(cell0+mid))->coord[axis];
+    depth++;
+    node->children[0] = buildTree(cell0, mid, depth, minBound, tmpBound);
+    
+    memcpy(tmpBound, minBound, sizeof(coords));
+    tmpBound[axis] = (*(cell0+mid))->coord[axis];
+    node->children[1] = buildTree(cell0+mid, Ncells-mid, depth, 
+				  tmpBound, maxBound);
+
+#ifdef __KDLEAF_TREE_NUMNODES
+    node->numNodes = (node->children[0] != 0) ? node->children[0]->numNodes : 0;
+    node->numNodes += (node->children[1] != 0) ? node->children[1]->numNodes : 0;
+#endif
+
+    return node;
+  }
+
+  template<int N, typename ValType, typename CType>
+  uint32_t KDLeafTree<N,ValType,CType>::countActives() const
+  {
+    uint32_t numActive = 0;
+    for (uint32_t i = 0; i < lastNode; i++)
+      {
+	if (nodes[i].value->active)
+	  numActive++;
+      }
+    return numActive;
+  }
+
+  template<int N, typename ValType, typename CType>
+  typename KDLeafDef<N,CType>::CoordType
+  KDLeafTree<N,ValType,CType>::computeDistance(const Cell *cell, const coords& x) const
+  {
+    CoordType d2 = 0;
+
+    for (int i = 0; i < N; i++)
+      {
+	CoordType delta = cell->coord[i] - x[i];
+	d2 += delta*delta;
+      }
+    return d2;
+  }
+
+ template<int N, typename ValType, typename CType>
+ double KDLeafTree<N,ValType,CType>::countInRange(CType sLo, CType sHigh, Node *root1, Node *root2) const
+ {
+   double result = recursiveCountInRange((root1 == 0) ? root : root1,
+				(root2 == 0) ? root : root2, 
+				sLo*sLo, sHigh*sHigh); 
+   return result;
+ }
+
+ 
+ template<int N, typename ValType, typename CType>
+ double KDLeafTree<N,ValType,CType>::recursiveCountInRange(Node *na, Node *nb,
+                                                         CType sLo, CType sHi) const
+ {
+   assert(nb != 0);
+   if (na == 0)
+     {
+       return 0;
+     }
+   
+   uint32_t numNa = getNumberInNode(na);
+   uint32_t numNb = getNumberInNode(nb);
+   double Cleft, Cright;
+   CType minDist, maxDist;
+
+   if (numNa == 1 && numNb == 1)
+     {
+       assert(na->leaf && nb->leaf);
+       CType ab_dist = computeDistance(na->value, nb->value->coord);
+       if (ab_dist >= sLo && ab_dist < sHi)
+	 return 1;
+       else
+	 return 0;
+     }
+   assert(numNa > 1 || numNb > 1);
+   
+   bool overlapping_a = true, overlapping_b = true;
+   for (int k = 0; k < N; k++) 
+     {
+       bool min_a_in_B = 
+	 ((na->minBound[k] >= nb->minBound[k] && 
+	   na->minBound[k] <= nb->maxBound[k]));
+       bool max_a_in_B =
+	 ((na->maxBound[k] >= nb->minBound[k] && 
+	   na->maxBound[k] <= nb->maxBound[k]));
+       bool min_b_in_A = 
+	 ((nb->minBound[k] >= na->minBound[k] && 
+	   nb->minBound[k] <= na->maxBound[k]));
+       bool max_b_in_A = 
+	 ((nb->maxBound[k] >= na->minBound[k] && 
+	   nb->maxBound[k] <= na->maxBound[k]));
+
+      if (!min_a_in_B && !max_a_in_B)
+         overlapping_a = false;
+      if (!min_b_in_A && !max_b_in_A)
+         overlapping_b = false;
+     }
+
+   if (overlapping_a || overlapping_b)
+     {
+        minDist = 0;
+        maxDist = 0;
+        for (int k = 0; k < N; k++)
+        {
+          CType delta = max(nb->maxBound[k]-na->minBound[k],na->maxBound[k]-nb->minBound[k]);
+          maxDist += delta*delta;
+        }
+     }
+   else
+     {
+       minDist = maxDist = 0;
+       for (int k = 0; k < N; k++)
+         {
+           CType delta2;
+           delta2 = max(nb->maxBound[k]-na->minBound[k],
+			na->maxBound[k]-nb->minBound[k]);
+           maxDist += delta2*delta2;
+         }
+       // mins and maxs
+       CType minmax[N][2];
+       for (int k = 0; k < N; k++)
+	 {
+	   if (na->minBound[k] < nb->minBound[k])
+	     {
+	       minmax[k][1] = na->maxBound[k];
+	       minmax[k][0] = nb->minBound[k];
+	     }
+	   else
+	     {
+	       minmax[k][1] = nb->maxBound[k];
+	       minmax[k][0] = na->minBound[k];
+	     }
+	 }
+       for (int k = 0; k < N; k++)
+	 {
+	   CType delta = max(minmax[k][0]-minmax[k][1], 0.);
+	   minDist += delta*delta;
+	 }
+     }
+   
+   if (minDist >= sHi)
+     return 0;
+   if (maxDist < sLo)
+     return 0;
+   
+   if (sLo <= minDist && maxDist < sHi)
+     return ((double)numNa)*numNb;
+   
+   if (numNa < numNb) 
+     {
+       assert(!nb->leaf);
+       Cleft = recursiveCountInRange(nb->children[0], na, sLo, sHi);
+       Cright = recursiveCountInRange(nb->children[1], na, sLo, sHi);
+     }
+   else
+     {
+       assert(!na->leaf);
+       Cleft = recursiveCountInRange(na->children[0], nb, sLo, sHi);
+       Cright = recursiveCountInRange(na->children[1], nb, sLo, sHi);
+     }
+   return Cleft+Cright;
+ }
+
+};