diff --git a/main.cpp b/main.cpp
index be7b47d..af970d4 100644
--- a/main.cpp
+++ b/main.cpp
@@ -17,7 +17,8 @@
 stim::camera cam;
 int mx, my;			//mouse coordinates in the window space
 
-stim::gl_spharmonics<double> S;
+stim::spharmonics<double> S;
+stim::gl_spharmonics<double> R;				//spherical harmonics to render
 
 float d = 1.5;		//initial distance between the camera and the sphere
 
@@ -27,6 +28,12 @@ stim::arglist args;			//class for processing command line arguments
 
 bool zaxis = false;			//render the z-axis (set via a command line flag)
 
+/// INTERPOLATION
+stim::gl_spharmonics<double> Si;
+bool interp = false;				//if we are interpolating
+float alpha = 0.0;					//alpha value for interpolation
+float dalpha = 0.1;					//change in alpha value with a key press
+
 bool init(){
 
 	//set the clear color to white
@@ -38,7 +45,7 @@ bool init(){
 	cam.setFOV(40);
 
 	//initialize the texture map stuff	
-	S.glInit(256);
+	R.glInit(256);
 
 	return true;
 }
@@ -67,7 +74,12 @@ void display(){
 	gluLookAt(p[0], p[1], p[2], d[0], d[1], d[2], u[0], u[1], u[2]);
 
 	//draw the sphere
-	S.glRender();
+	if (interp)
+		R = (S * (1.0f - alpha) + Si * alpha);
+	else
+		R = S;
+	R.glRender();
+
 
 	//glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
 
@@ -130,7 +142,7 @@ std::vector<stim::vec3 <float> >
 sample_sphere(int num_samples, float radius = 1.0)
 {
 
-	float solidAngle = 2*stim::PI;	///Solid angle to sample over
+	float solidAngle = stim::TAU;	///Solid angle to sample over
 	float PHI[2], Z[2], range;	///Range of angles in cylinderical coordinates
 	PHI[0] = solidAngle/2;		///project the solid angle into spherical coords
 	PHI[1] = asin(0);		///
@@ -148,7 +160,7 @@ sample_sphere(int num_samples, float radius = 1.0)
 	for(int i = 0; i < num_samples; i++)
 	{
 		z = uniformRandom()*range + Z[1];
-		theta = uniformRandom()*stim::TAU;
+		theta = uniformRandom() * stim::TAU;
 		phi = acos(z);
 		stim::vec3<float> sph(1, theta, phi);
 		stim::vec3<float> cart = sph.sph2cart();
@@ -185,6 +197,7 @@ void process_arguments(int argc, char* argv[]){
 	args.add("out", "filename for outputting spherical harmonics coefficients", "", "filename");
 	args.add("zaxis", "render the z-axis as a green line");
 	args.add("pdf", "outputs the PDF if an OBJ files is given");
+	args.add("interp", "interpolates between two specified sets of coefficients", "", "[c0 c1 c2 c3 ...]");
 
 	//process the command line arguments
 	args.parse(argc, argv);
@@ -193,6 +206,11 @@ void process_arguments(int argc, char* argv[]){
 	if(args["zaxis"].is_set())
 		zaxis = true;
 
+	if (args["interp"]) {											//if an interpolation harmonic is provided
+		for (unsigned int a = 0; a < args["interp"].nargs(); a++)
+			Si.push(args["interp"].as_float(a));
+	}
+
 	//if arguments are specified, push them as coefficients
 	if(args.nargs() > 0){
 		//push all of the arguments to the spherical harmonics class as coefficients
--
libgit2 0.21.4