diff --git a/stim/image/image.h b/stim/image/image.h
index c093405..71150ae 100644
--- a/stim/image/image.h
+++ b/stim/image/image.h
@@ -66,7 +66,7 @@ public:
 	void data_interleaved(T* data){
 
 		unsigned int C = channels();
-		unsigned int X = size();
+		unsigned int X = width() * height();
 
 		T* ptr = img.data();
 
@@ -105,6 +105,55 @@ public:
 		return img.size();
 	}
 
+	/// Returns the number of nonzero values
+	unsigned int nnz(){
+
+		unsigned long P = width() * height();
+		unsigned long C = channels();
+
+		T* ptr = img.data();
+
+		unsigned long n = 0;
+
+		for(unsigned long p = 0; p < P; p++){
+			for(unsigned long c = 0; c < C; c++){
+
+				if(ptr[c * P + p] > 0){
+					n++;
+					break;
+				}
+			}
+		}
+
+		return n;	//return the number of nonzero pixels
+
+	}
+
+	//this function returns indices of pixels that have nonzero values
+	std::vector<unsigned long> sparse_idx(){
+
+		std::vector<unsigned long> s;		//allocate an array
+		s.resize(nnz());					//allocate space in the array
+
+		unsigned long P = width() * height();
+		unsigned long C = channels();
+
+		T* ptr = img.data();				//get a pointer to the image data
+
+		unsigned long i = 0;
+		for(unsigned long p = 0; p < P; p++){
+			for(unsigned long c = 0; c < C; c++){
+
+				if(ptr[c * P + p] > 0){
+					s[i] = p;
+					i++;
+					break;
+				}
+			}
+		}
+
+		return s;			//return the index list
+	}
 	
 
 
diff --git a/stim/math/vector.h b/stim/math/vector.h
index fe8afed..43b5e14 100644
--- a/stim/math/vector.h
+++ b/stim/math/vector.h
@@ -54,6 +54,16 @@ struct vec : public std::vector<T>
 		at(3) = w;
 	}
 
+	vec(std::string str){
+		std::stringstream ss(str);
+
+		T c;
+		while(ss >> c){
+			push_back(c);
+		}
+
+	}
+
 	
 	
 	//copy constructor
diff --git a/stim/parser/filename.h b/stim/parser/filename.h
index dc6b4da..f4aa800 100644
--- a/stim/parser/filename.h
+++ b/stim/parser/filename.h
@@ -20,7 +20,7 @@
 
 #include "../parser/parser.h"
 
-#include <boost/filesystem.hpp>
+//#include <boost/filesystem.hpp>
 
 namespace stim{
 
@@ -154,8 +154,8 @@ public:
 
 		return ss.str();
 	}
-
-	//get a list of files matching the current tamplate
+/*
+	//get a list of files matching the current template
 	std::vector<stim::filename> get_list(){
 
 		boost::filesystem::path p(dir());	//create a path from the current filename
@@ -193,7 +193,7 @@ public:
 
 		return file_list;
 	}
-
+*/
 	//gets the current working directory
 	static stim::filename cwd(){
 
--
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