diff --git a/FDTD/operator_ext_pml_sf.cpp b/FDTD/operator_ext_pml_sf.cpp
index a3e760d..4205b92 100644
--- a/FDTD/operator_ext_pml_sf.cpp
+++ b/FDTD/operator_ext_pml_sf.cpp
@@ -21,17 +21,31 @@
 #include "tools/array_ops.h"
 #include "fparser.hh"
 
-bool Build_Split_Field_PML(Operator* op, int BC[6], int size[6])
+bool Build_Split_Field_PML(Operator* op, int BC[6], int size[6], string gradFunc)
 {
 	for (int n=0;n<6;++n)
 	{
 		if (BC[n]==3) //split field PML
 		{
-			cerr << "Build_Split_Field_PML:: Warning, currently only pml planes are implemented... edges and corner coming soon..." << endl;
 			Operator_Ext_PML_SF_Plane* op_pml_sf = new Operator_Ext_PML_SF_Plane(op);
 			op_pml_sf->SetDirection(n/2,n%2);
+			if ((size[n]<4) || (size[n]>50))
+			{
+				cerr << "Build_Split_Field_PML: Warning, pml size invalid, skipping pml..." << endl;
+				delete op_pml_sf;
+				continue;
+			}
 			op_pml_sf->SetPMLLength(size[n]);
 			op_pml_sf->SetBoundaryCondition(BC);
+
+			if (!op_pml_sf->SetGradingFunction(gradFunc))
+			{
+				cerr << "Build_Split_Field_PML: Warning, pml grading function invalid, skipping pml..." << endl;
+				delete op_pml_sf;
+				continue;
+			}
+
+			cerr << "Build_Split_Field_PML:: Warning, currently only pml planes are implemented... edges and corner coming soon..." << endl;
 			op->AddExtension(op_pml_sf);
 		}
 	}
@@ -112,7 +126,11 @@ void Operator_Ext_PML_SF::DeleteOP()
 
 bool Operator_Ext_PML_SF::SetGradingFunction(string func)
 {
-	int res = m_GradingFunction->Parse(func.c_str(), "D,dl,W,Z,N");
+	if (func.empty())
+		return true;
+
+	m_GradFunc = func;
+	int res = m_GradingFunction->Parse(m_GradFunc.c_str(), "D,dl,W,Z,N");
 	if(res < 0) return true;
 
 	cerr << "Operator_Ext_PML_SF::SetGradingFunction: Warning, an error occured parsing the pml grading function (see below) ..." << endl;
@@ -401,4 +419,5 @@ void Operator_Ext_PML_SF_Plane::ShowStat(ostream &ostr)  const
 	string top_bot[2] = {"bottom", "top"};
 	ostr << " Active direction\t: " << XYZ[m_ny] << " (" << top_bot[m_top] << ")" << endl;
 	ostr << " PML width (cells)\t: " << m_numLines[m_ny] << endl;
+	ostr << " Grading function\t: \"" << m_GradFunc << "\"" << endl;
 }
diff --git a/FDTD/operator_ext_pml_sf.h b/FDTD/operator_ext_pml_sf.h
index a079cb6..28f6077 100644
--- a/FDTD/operator_ext_pml_sf.h
+++ b/FDTD/operator_ext_pml_sf.h
@@ -24,7 +24,7 @@
 class FunctionParser;
 
 //! Insert split field pml planes, edges and corner as necessary by the given boundary conditions
-bool Build_Split_Field_PML(Operator* op, int BC[6], int size[6]);
+bool Build_Split_Field_PML(Operator* op, int BC[6], int size[6], string gradFunc);
 
 //! This is the abstract operator extension for truncating the FDTD domain with a split field pml
 class Operator_Ext_PML_SF : public Operator_Extension
@@ -57,6 +57,8 @@ public:
 			N  = number of cells for the pml
 			Z  = wave impedance at the current depth and position
 		example: SetGradingFunction("-log(1e-6)*log(2.5)/(2*dl*pow(2.5,W/dl)-1) * pow(2.5, D/dl) / Z");
+
+		An empty function string will be ignored.
 	*/
 	virtual bool SetGradingFunction(string func);
 
@@ -78,6 +80,7 @@ protected:
 
 	int m_BC[6];
 
+	string m_GradFunc;
 	FunctionParser* m_GradingFunction;
 
 	void InitOP();
diff --git a/openems.cpp b/openems.cpp
index 84f2c1c..bdfb118 100644
--- a/openems.cpp
+++ b/openems.cpp
@@ -159,6 +159,10 @@ bool openEMS::SetupBoundaryConditions(TiXmlElement* BC)
 	int bounds[6] = {0,0,0,0,0,0};   //default boundary cond. (PEC)
 	int pml_size[6] = {8,8,8,8,8,8}; //default pml size
 	string s_bc;
+	const char* tmp = BC->Attribute("PML_Grading");
+	string pml_gradFunc;
+	if (tmp)
+		pml_gradFunc = string(tmp);
 
 	string bound_names[] = {"xmin","xmax","ymin","ymax","zmin","zmax"};
 
@@ -169,7 +173,9 @@ bool openEMS::SetupBoundaryConditions(TiXmlElement* BC)
 			continue;
 		if (EC==TIXML_WRONG_TYPE)
 		{
-			s_bc = string(BC->Attribute(bound_names[n].c_str()));
+			tmp = BC->Attribute(bound_names[n].c_str());
+			if (tmp)
+				s_bc = string(tmp);
 			if (s_bc=="PEC")
 				bounds[n] = 0;
 			else if (s_bc=="PMC")
@@ -201,7 +207,7 @@ bool openEMS::SetupBoundaryConditions(TiXmlElement* BC)
 			FDTD_Op->AddExtension(op_ext_mur);
 		}
 	}
-	Build_Split_Field_PML(FDTD_Op,bounds,pml_size);
+	Build_Split_Field_PML(FDTD_Op,bounds,pml_size,pml_gradFunc);
 
 	return true;
 }