diff --git a/sunkit_image/asda.py b/sunkit_image/asda.py
index f97b875c..6cb1df68 100644
--- a/sunkit_image/asda.py
+++ b/sunkit_image/asda.py
@@ -9,7 +9,7 @@
 import numpy as np
 from skimage import measure
 
-from sunkit_image.utils import calc_gamma, points_in_poly, reform2d, remove_duplicate
+from sunkit_image.utils import calculate_gamma, points_in_poly, reform2d, remove_duplicate
 
 __all__ = ["Asda", "Lamb_Oseen"]
 
@@ -134,7 +134,7 @@ def gamma_values(self):
         for d, (i, j) in enumerate(
             product(np.arange(self.r, self.dshape[0] - self.r, 1), np.arange(self.r, self.dshape[1] - self.r, 1))
         ):
-            self.gamma[i, j, 0], self.gamma[i, j, 1] = calc_gamma(pm, vel[..., d], pnorm, N)
+            self.gamma[i, j, 0], self.gamma[i, j, 1] = calculate_gamma(pm, vel[..., d], pnorm, N)
         # Transpose back vx & vy
         self.vx = self.vx.T
         self.vy = self.vy.T
@@ -206,16 +206,15 @@ def vortex_property(self, image=None):
             Has to have the same shape as ``self.vx`` observational image,
             which will be used to calculate the average observational values of all swirls.
 
-        Outputs
+        Returns
         -------
         `tuple`
-            The returned tuple has four components, each component in order is
-            ``ve``: expanding speed, in the same unit as ``self.vx`` or ``self.vy``.
-            ``vr``: rotational speed, in the same unit as ``self.vx`` or ``self.vy``.
-            ``vc``: velocity of the center, in the form of ``[vx, vy]``.
-            ``ia``: average of the observational values (intensity or magnetic
-                field strength etc) within the vortices if the parameter
-                image is given.
+            The returned tuple has four components, which are:
+
+            ``ve`` : expanding speed, in the same unit as ``self.vx`` or ``self.vy``.
+            ``vr`` : rotational speed, in the same unit as ``self.vx`` or ``self.vy``.
+            ``vc`` : velocity of the center, in the form of ``[vx, vy]``.
+            ``ia`` : average of the observational values within the vortices if the parameter image is given.
         """
         ve, vr, vc, ia = (), (), (), ()
         for i in range(len(self.edge_prop["center"])):
diff --git a/sunkit_image/utils/tests/test_utils.py b/sunkit_image/utils/tests/test_utils.py
index acd3b3e8..a07bb2c0 100644
--- a/sunkit_image/utils/tests/test_utils.py
+++ b/sunkit_image/utils/tests/test_utils.py
@@ -139,7 +139,7 @@ def test_calculate_gamma():
     vel_norm = np.linalg.norm(vel[..., 0], axis=2)
     sint = cross / (pnorm * vel_norm + 1e-10)
     expected = np.nansum(sint, axis=1) / N
-    assert np.allclose(expected, utils.calc_gamma(pm, vel[..., 0], pnorm, N))
+    assert np.allclose(expected, utils.calculate_gamma(pm, vel[..., 0], pnorm, N))
 
 
 def test_remove_duplicate():
diff --git a/sunkit_image/utils/utils.py b/sunkit_image/utils/utils.py
index 684f22f4..7eb305b8 100644
--- a/sunkit_image/utils/utils.py
+++ b/sunkit_image/utils/utils.py
@@ -12,7 +12,7 @@
 
 __all__ = [
     "bin_edge_summary",
-    "calc_gamma",
+    "calculate_gamma",
     "equally_spaced_bins",
     "find_pixel_radii",
     "get_radial_intensity_summary",
@@ -252,7 +252,7 @@ def remove_duplicate(edge):
     return new_edge
 
 
-def calc_gamma(pm, vel, pnorm, N):
+def calculate_gamma(pm, vel, pnorm, n):
     """
     Calculate gamma values.
 
@@ -264,7 +264,7 @@ def calc_gamma(pm, vel, pnorm, N):
         Velocity vector.
     pnorm : `numpy.ndarray`
         Mode of ``pm``.
-    N : `int`
+    n : `int`
         Number of points.
 
     Returns
@@ -288,4 +288,4 @@ def calc_gamma(pm, vel, pnorm, N):
     cross = np.cross(pm, vel)
     vel_norm = np.linalg.norm(vel, axis=2)
     sint = cross / (pnorm * vel_norm + 1e-10)
-    return np.nansum(sint, axis=1) / N
+    return np.nansum(sint, axis=1) / n