diff --git a/FDTD/operator_sse_compressed.cpp b/FDTD/operator_sse_compressed.cpp
index f89de23..ce1da9b 100644
--- a/FDTD/operator_sse_compressed.cpp
+++ b/FDTD/operator_sse_compressed.cpp
@@ -20,7 +20,8 @@
 #include "engine_sse.h"
 #include "tools/array_ops.h"
 
-#include <list>
+#include <map>
+#include <cstring>
 
 Operator_SSE_Compressed* Operator_SSE_Compressed::New()
 {
@@ -34,19 +35,6 @@ Operator_SSE_Compressed::Operator_SSE_Compressed() : Operator_sse()
 {
 	m_Op_index = NULL;
 	m_Use_Compression = false;
-	m_Max_Compression = false;
-
-	m_Compression_Threshold = 0.8;
-
-	for (int n=0;n<3;++n)
-	{
-		f4_vv_Compressed[n]=NULL;
-		f4_vi_Compressed[n]=NULL;
-		f4_ii_Compressed[n]=NULL;
-		f4_iv_Compressed[n]=NULL;
-	}
-
-	m_max_fifo = 0;
 }
 
 Operator_SSE_Compressed::~Operator_SSE_Compressed()
@@ -56,7 +44,7 @@ Operator_SSE_Compressed::~Operator_SSE_Compressed()
 
 Engine* Operator_SSE_Compressed::CreateEngine() const
 {
-	if (m_Use_Compression==false)
+        if (!m_Use_Compression)
 	{
 		//! create a default sse-engine
 		Engine_sse* eng = Engine_sse::New(this);
@@ -78,13 +66,6 @@ void Operator_SSE_Compressed::Init()
 {
 	Operator_sse::Init();
 	m_Op_index = NULL;
-	for (int n=0;n<3;++n)
-	{
-		f4_vv_Compressed[n]=NULL;
-		f4_vi_Compressed[n]=NULL;
-		f4_ii_Compressed[n]=NULL;
-		f4_iv_Compressed[n]=NULL;
-	}
 }
 
 void Operator_SSE_Compressed::Reset()
@@ -106,17 +87,13 @@ void Operator_SSE_Compressed::Reset()
 		m_Op_index = NULL;
 	}
 
-	for (int n=0;n<3;++n)
-	{
-		Delete1DArray_v4sf(f4_vv_Compressed[n]);
-		f4_vv_Compressed[n]=NULL;
-		Delete1DArray_v4sf(f4_vi_Compressed[n]);
-		f4_vi_Compressed[n]=NULL;
-		Delete1DArray_v4sf(f4_ii_Compressed[n]);
-		f4_ii_Compressed[n]=NULL;
-		Delete1DArray_v4sf(f4_iv_Compressed[n]);
-		f4_iv_Compressed[n]=NULL;
-	}
+        for (int n=0; n<3; n++)
+        {
+                f4_vv_Compressed[n].clear();
+                f4_vi_Compressed[n].clear();
+                f4_iv_Compressed[n].clear();
+                f4_ii_Compressed[n].clear();
+        }
 }
 
 void Operator_SSE_Compressed::InitOperator()
@@ -143,10 +120,8 @@ void Operator_SSE_Compressed::ShowStat() const
 {
 	Operator_sse::ShowStat();
 
-	string yes_no[2] = {"no","yes"};
-	cout << "SSE compression enabled\t: " << yes_no[m_Use_Compression] << endl;
-	cout << "Unique SSE operator\t: " << m_Op_Count << endl;
-	cout << "Optimal compression\t: " << yes_no[m_Max_Compression] << endl;
+        cout << "SSE compression enabled\t: " << (m_Use_Compression?"yes":"no") << endl;
+        cout << "Unique SSE operators\t: " << f4_vv_Compressed->size() << endl;
 	cout << "-----------------------------------" << endl;
 }
 
@@ -176,14 +151,6 @@ bool Operator_SSE_Compressed::CompareOperators(unsigned int pos1[3], unsigned in
 		if (!equal( f4_vi[n][pos1[0]][pos1[1]][pos1[2]], f4_vi[n][pos2[0]][pos2[1]][pos2[2]] )) return false;
 		if (!equal( f4_iv[n][pos1[0]][pos1[1]][pos1[2]], f4_iv[n][pos2[0]][pos2[1]][pos2[2]] )) return false;
 		if (!equal( f4_ii[n][pos1[0]][pos1[1]][pos1[2]], f4_ii[n][pos2[0]][pos2[1]][pos2[2]] )) return false;
-
-//		for (int m=0;m<4;++m)
-//		{
-//			if (f4_vv[n][pos1[0]][pos1[1]][pos1[2]].f[m] != f4_vv[n][pos2[0]][pos2[1]][pos2[2]].f[m])	return false;
-//			if (f4_vi[n][pos1[0]][pos1[1]][pos1[2]].f[m] != f4_vi[n][pos2[0]][pos2[1]][pos2[2]].f[m])	return false;
-//			if (f4_iv[n][pos1[0]][pos1[1]][pos1[2]].f[m] != f4_iv[n][pos2[0]][pos2[1]][pos2[2]].f[m])	return false;
-//			if (f4_ii[n][pos1[0]][pos1[1]][pos1[2]].f[m] != f4_ii[n][pos2[0]][pos2[1]][pos2[2]].f[m])	return false;
-//		}
 	}
 	return true;
 }
@@ -192,85 +159,47 @@ bool Operator_SSE_Compressed::CompressOperator()
 {
 	cout << "Compressing the FDTD operator... this may take a while..." << endl;
 
-	if (m_max_fifo==0)
-	{
-		m_max_fifo = numVectors*numLines[1] + 1;
-//		cerr << m_max_fifo << endl;
-	}
+        map<SSE_coeff,unsigned int> lookUpMap;
 
-	m_Max_Compression = true;
-
-	list<unsigned int> fifo;
-	vector<unsigned int> index_list[3];
-
-	bool found;
 	unsigned int pos[3];
-	unsigned int index_pos[3];
-	list<unsigned int>::iterator it;
 	for (pos[0]=0;pos[0]<numLines[0];++pos[0])
 	{
 		for (pos[1]=0;pos[1]<numLines[1];++pos[1])
 		{
 			for (pos[2]=0;pos[2]<numVectors;++pos[2])
 			{
-				found = false;
-				for ( it=fifo.begin() ; it != fifo.end(); it++ )
-				{
-					index_pos[0] = index_list[0].at(*it);
-					index_pos[1] = index_list[1].at(*it);
-					index_pos[2] = index_list[2].at(*it);
-					found = CompareOperators(index_pos, pos);
-					if (found)
-					{
-						m_Op_index[pos[0]][pos[1]][pos[2]] = *it;
-						fifo.push_front(*it);	//push already existing value to the front
-						fifo.erase(it);
-						it = fifo.end();
-						++it;
-						break;
-					}
-				}
-				if (found==false)
-				{
-					fifo.push_front(index_list[0].size());
-					m_Op_index[pos[0]][pos[1]][pos[2]] = index_list[0].size();
-					index_list[0].push_back(pos[0]);
-					index_list[1].push_back(pos[1]);
-					index_list[2].push_back(pos[2]);
-				}
-				if (fifo.size()>m_max_fifo)
-				{
-					fifo.pop_back();
-					m_Max_Compression = false;
-				}
+                                f4vector vv[3] = { f4_vv[0][pos[0]][pos[1]][pos[2]], f4_vv[1][pos[0]][pos[1]][pos[2]], f4_vv[2][pos[0]][pos[1]][pos[2]] };
+                                f4vector vi[3] = { f4_vi[0][pos[0]][pos[1]][pos[2]], f4_vi[1][pos[0]][pos[1]][pos[2]], f4_vi[2][pos[0]][pos[1]][pos[2]] };
+                                f4vector iv[3] = { f4_iv[0][pos[0]][pos[1]][pos[2]], f4_iv[1][pos[0]][pos[1]][pos[2]], f4_iv[2][pos[0]][pos[1]][pos[2]] };
+                                f4vector ii[3] = { f4_ii[0][pos[0]][pos[1]][pos[2]], f4_ii[1][pos[0]][pos[1]][pos[2]], f4_ii[2][pos[0]][pos[1]][pos[2]] };
+                                SSE_coeff c( vv, vi, iv, ii );
+
+                                map<SSE_coeff,unsigned int>::iterator it;
+                                it = lookUpMap.find(c);
+                                if (it == lookUpMap.end())
+                                {
+                                        // not found -> insert
+                                        unsigned int index = f4_vv_Compressed[0].size();
+                                        for (int n=0; n<3; n++)
+                                        {
+                                                f4_vv_Compressed[n].push_back( vv[n] );
+                                                f4_vi_Compressed[n].push_back( vi[n] );
+                                                f4_iv_Compressed[n].push_back( iv[n] );
+                                                f4_ii_Compressed[n].push_back( ii[n] );
+                                        }
+                                        lookUpMap[c] = index;
+                                        m_Op_index[pos[0]][pos[1]][pos[2]] = index;
+                                }
+                                else
+                                {
+                                        // this operator is already in the list
+                                        unsigned int index = (*it).second;
+                                        m_Op_index[pos[0]][pos[1]][pos[2]] = index;
+                                }
 			}
 		}
 	}
 
-	m_Op_Count = index_list[0].size();
-	if ( ((double)m_Op_Count/(double)GetNumberCells()) > m_Compression_Threshold)
-	{
-		cerr << "Operator_SSE_Compressed::CompressOperator: Warning: Compression unsuccessful, ratio is " << (double)m_Op_Count/(double)GetNumberCells() << "! Fallback to conventional sse-engine..." << endl;
-		return false;
-	}
-//	cerr << "total found: " << index_list[0].size() << endl;
-
-	for (int n=0;n<3;++n)
-	{
-		f4_vv_Compressed[n] = Create1DArray_v4sf(m_Op_Count);
-		f4_vi_Compressed[n] = Create1DArray_v4sf(m_Op_Count);
-		f4_ii_Compressed[n] = Create1DArray_v4sf(m_Op_Count);
-		f4_iv_Compressed[n] = Create1DArray_v4sf(m_Op_Count);
-
-		for (unsigned int m=0;m<m_Op_Count;++m)
-		{
-			f4_vv_Compressed[n][m].v = f4_vv[n][index_list[0].at(m)][index_list[1].at(m)][index_list[2].at(m)].v;
-			f4_vi_Compressed[n][m].v = f4_vi[n][index_list[0].at(m)][index_list[1].at(m)][index_list[2].at(m)].v;
-			f4_ii_Compressed[n][m].v = f4_ii[n][index_list[0].at(m)][index_list[1].at(m)][index_list[2].at(m)].v;
-			f4_iv_Compressed[n][m].v = f4_iv[n][index_list[0].at(m)][index_list[1].at(m)][index_list[2].at(m)].v;
-		}
-	}
-
 	Delete_N_3DArray_v4sf(f4_vv,numLines);
 	Delete_N_3DArray_v4sf(f4_vi,numLines);
 	Delete_N_3DArray_v4sf(f4_iv,numLines);
@@ -282,3 +211,75 @@ bool Operator_SSE_Compressed::CompressOperator()
 
 	return true;
 }
+
+
+
+
+// ----------------------------------------------------------------------------
+
+SSE_coeff::SSE_coeff( f4vector vv[3], f4vector vi[3], f4vector iv[3], f4vector ii[3] )
+{
+        for (int n=0; n<3; n++) {
+                m_vv[n] = vv[n];
+                m_vi[n] = vi[n];
+                m_iv[n] = iv[n];
+                m_ii[n] = ii[n];
+        }
+}
+
+bool SSE_coeff::operator==( const SSE_coeff& other ) const
+{
+        for (int n=0; n<3; n++)
+        {
+                if (memcmp( &(m_vv[n]), &(other.m_vv[n]), sizeof(f4vector) ) != 0) return false;
+                if (memcmp( &(m_vi[n]), &(other.m_vi[n]), sizeof(f4vector) ) != 0) return false;
+                if (memcmp( &(m_iv[n]), &(other.m_iv[n]), sizeof(f4vector) ) != 0) return false;
+                if (memcmp( &(m_ii[n]), &(other.m_ii[n]), sizeof(f4vector) ) != 0) return false;
+        }
+        return true;
+}
+bool SSE_coeff::operator!=( const SSE_coeff& other ) const
+{
+        return !(*this == other);
+}
+bool SSE_coeff::operator<( const SSE_coeff& other ) const
+{
+        for (int n=0; n<3; n++)
+        {
+                for (int c=0; c<4; c++)
+                {
+                        if (m_vv[n].f[c] > other.m_vv[n].f[c]) return false;
+                        if (m_vv[n].f[c] < other.m_vv[n].f[c]) return true;
+                        if (m_vi[n].f[c] > other.m_vi[n].f[c]) return false;
+                        if (m_vi[n].f[c] < other.m_vi[n].f[c]) return true;
+                        if (m_iv[n].f[c] > other.m_iv[n].f[c]) return false;
+                        if (m_iv[n].f[c] < other.m_iv[n].f[c]) return true;
+                        if (m_ii[n].f[c] > other.m_ii[n].f[c]) return false;
+                        if (m_ii[n].f[c] < other.m_ii[n].f[c]) return true;
+                }
+        }
+        return false;
+}
+
+void SSE_coeff::print( ostream& stream ) const
+{
+        stream << "SSE_coeff: (" << endl;
+        for (int n=0; n<3; n++)
+        {
+                stream << "n=" << n << ":" << endl;
+                stream << "vv=";
+                for (int c=0; c<4; c++)
+                        stream << m_vv[n].f[c] << " ";
+                stream << endl << "vi=";
+                for (int c=0; c<4; c++)
+                        stream << m_vi[n].f[c] << " ";
+                stream << endl << "iv=";
+                for (int c=0; c<4; c++)
+                        stream << m_iv[n].f[c] << " ";
+                stream << endl << "ii=";
+                for (int c=0; c<4; c++)
+                        stream << m_ii[n].f[c] << " ";
+                stream << endl;
+        }
+        stream << ")" << endl;
+}
diff --git a/FDTD/operator_sse_compressed.h b/FDTD/operator_sse_compressed.h
index 30465f5..30a1f3d 100644
--- a/FDTD/operator_sse_compressed.h
+++ b/FDTD/operator_sse_compressed.h
@@ -20,6 +20,21 @@
 
 #include "operator_sse.h"
 
+class SSE_coeff
+{
+public:
+        SSE_coeff( f4vector vv[3], f4vector vi[3], f4vector iv[3], f4vector ii[3] );
+        bool operator==( const SSE_coeff& ) const;
+        bool operator!=( const SSE_coeff& ) const;
+        bool operator<( const SSE_coeff& ) const;
+        void print( ostream& stream ) const;
+protected:
+        f4vector m_vv[3];
+        f4vector m_vi[3];
+        f4vector m_iv[3];
+        f4vector m_ii[3];
+};
+
 class Operator_SSE_Compressed : public Operator_sse
 {
 public:
@@ -31,44 +46,35 @@ public:
 
 	virtual int CalcECOperator();
 
-	inline virtual FDTD_FLOAT& GetVV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_vv_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVV(n,x,y,z);}
-	inline virtual FDTD_FLOAT& GetVI( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_vi_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVI(n,x,y,z);}
+        inline virtual FDTD_FLOAT& GetVV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) { if (m_Use_Compression) return f4_vv_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVV(n,x,y,z);}
+        inline virtual FDTD_FLOAT& GetVI( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) { if (m_Use_Compression) return f4_vi_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVI(n,x,y,z);}
 
-	inline virtual FDTD_FLOAT& GetII( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_ii_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetII(n,x,y,z);}
-	inline virtual FDTD_FLOAT& GetIV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_iv_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetIV(n,x,y,z);}
+        inline virtual FDTD_FLOAT& GetII( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) { if (m_Use_Compression) return f4_ii_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetII(n,x,y,z);}
+        inline virtual FDTD_FLOAT& GetIV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) { if (m_Use_Compression) return f4_iv_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetIV(n,x,y,z);}
 
 	virtual void ShowStat() const;
 
-	void SetCompressionThreshold(double val) {m_Compression_Threshold = val;}
-	void SetCacheSize(unsigned int size) {m_max_fifo = size;}
 	bool CompressOperator();
 
 protected:
 	Operator_SSE_Compressed();
 
 	bool m_Use_Compression;
-	bool m_Max_Compression; //reached maximal compression?
-	unsigned int m_Op_Count;
-
-	//! Compression ratio threshold. If this ratio is exceeded, compression will be disabled. \sa SetCompressionThreshold()
-	double m_Compression_Threshold; //default is 0.8
 
 	virtual void Init();
 	virtual void Reset();
 	virtual void InitOperator();
 
-	//! Compression cache size, default is 1000 \sa SetCacheSize()
-	unsigned int m_max_fifo;
-
 	bool CompareOperators(unsigned int pos1[3], unsigned int pos2[3]);
 
 	// engine needs access
 public:
 	unsigned int*** m_Op_index;
-	f4vector* f4_vv_Compressed[3]; //calc new voltage from old voltage
-	f4vector* f4_vi_Compressed[3]; //calc new voltage from old current
-	f4vector* f4_iv_Compressed[3]; //calc new current from old current
-	f4vector* f4_ii_Compressed[3]; //calc new current from old voltage
+        vector<f4vector> f4_vv_Compressed[3]; //!< coefficient: calc new voltage from old voltage
+        vector<f4vector> f4_vi_Compressed[3]; //!< coefficient: calc new voltage from old current
+        vector<f4vector> f4_iv_Compressed[3]; //!< coefficient: calc new current from old current
+        vector<f4vector> f4_ii_Compressed[3]; //!< coefficient: calc new current from old voltage
+
 };
 
 #endif // OPERATOR_SSE_Compressed_H