diff --git a/c/interaction/interaction.c b/c/interaction/interaction.c
index 70adbbc..e178b9b 100644
--- a/c/interaction/interaction.c
+++ b/c/interaction/interaction.c
@@ -115,10 +115,11 @@ interaction_ufunc_float2D
 			// Update the momenta.
 			delta_p_x = delta_x_e * interaction_force_function(r, coefficients);
 			delta_p_y = delty_y_e * interaction_force_function(r, coefficients);
-			*(float *)(p_x_new + i*p_x_new_steps) -= delta_p_x;
-			*(float *)(p_y_new + i*p_y_new_steps) -= delta_p_y;
-			*(float *)(p_x_new + j*p_x_new_steps) += delta_p_x;
-			*(float *)(p_y_new + j*p_y_new_steps) += delta_p_y;
+			//printf("%d, %d: %f, %f\n", i, j, delta_p_x, delta_p_y);
+			*(float *)(p_x_new + i*p_x_new_steps) += delta_p_x;
+			*(float *)(p_y_new + i*p_y_new_steps) += delta_p_y;
+			*(float *)(p_x_new + j*p_x_new_steps) -= delta_p_x;
+			*(float *)(p_y_new + j*p_y_new_steps) -= delta_p_y;
 		}
 	}
 }
diff --git a/setup.py b/setup.py
index ec09553..20b4715 100644
--- a/setup.py
+++ b/setup.py
@@ -1,30 +1,31 @@
-#from distutils.core import setup, Extension
-#
-#
-#interaction = Extension("brown.interaction",
-#		sources = ["c/interaction/interaction.c"])
-#
-#setup(name = "brown",
-#	version = "0.0.1",
-#	description = "Me playing around with single-atom classical gases",
-#	ext_modules = [interaction],
-#	packages = [
-#		"brown"
-#	],
-#	package_dir = {"brown": "py/brown"},
-#	#url="https://github.com/daknuett/python3-nf",
-#	author = "Daniel Knüttel",
-#	author_email = "daniel.knuettel@daknuett.eu")
+from distutils.core import setup, Extension
 
-def configuration(parent_package='', top_path=None):
-	from numpy.distutils.misc_util import Configuration
 
-	config = Configuration('brown'
-			, parent_package
-			, top_path)
-	config.add_extension('interaction', ['c/interaction/interaction.c'], extra_compile_args=["-g"])
-	return config
+interaction = Extension("brown.interaction",
+		sources = ["c/interaction/interaction.c"])
 
-if __name__ == "__main__":
-	from numpy.distutils.core import setup
-	setup(configuration=configuration)
+setup(name = "brown",
+	version = "0.0.1",
+	description = "Me playing around with single-atom classical gases",
+	ext_modules = [interaction],
+	packages = [
+		"brown"
+	],
+	package_dir = {"brown": "py/brown"},
+	#url="https://github.com/daknuett/python3-nf",
+	author = "Daniel Knüttel",
+	author_email = "daniel.knuettel@daknuett.eu")
+
+#def configuration(parent_package='', top_path=None):
+#	from numpy.distutils.misc_util import Configuration
+#
+#	config = Configuration('brown'
+#			, parent_package
+#			, top_path="py/")
+#	config.add_extension('interaction', ['c/interaction/interaction.c'], extra_compile_args=["-g"])
+#	#config.add_subpackage("brown.brown", "py/brown")
+#	return config
+#
+#if __name__ == "__main__":
+#	from numpy.distutils.core import setup
+#	setup(configuration=configuration)
diff --git a/test.py b/test.py
index 25b8cd5..beb8dd3 100644
--- a/test.py
+++ b/test.py
@@ -14,14 +14,16 @@ y_coords = np.array([0, 0], dtype=np.float16)
 x_momenta = np.array([0, 0], dtype=np.float16)
 y_momenta = np.array([0, 0], dtype=np.float16)
 
-time = np.arange(0, 5, 1, dtype=np.float16)
+time = np.arange(0, 50, 1, dtype=np.float16)
 
 time_evolution = deque()
 
+dt = 0.1
+
 for t in time:
 	x_momenta, y_momenta = interaction2D(x_coords, y_coords, x_momenta, y_momenta)
-	x_coords += x_momenta
-	y_coords += y_momenta
+	x_coords += dt * x_momenta
+	y_coords += dt * y_momenta
 
 	time_evolution.append(copy(x_coords))