Merge pull request #74 from NeuroHackademy2024/20-update-spherepy-fun…

…ction

add a function to calculate volume #20

src/geometry/sphere.py

@@ -1,20 +1,35 @@
 from math import pi
 
 
-def calculate_surface_area(r):
+def calculate_volume(r):
     """ 
-    Calculate the surface area of a sphere. 
+    Calculate the volume of a sphere. 
 
     This uses the standard mathematical calculation: 
 
-    $4\pi r ^2$
+    $(4 * \pi r ^3) / 3$
 
     Parameters
     ----------
     r : float, the radius 
 
     Returns
     -------
+    float : the volume of the sphere
+    """
+
+    volume = (4 * pi * r **3) / 3
+    return volume
+
+
+def calculate_surface_area(r):
+    """ 
+    Calculate the surface area of a sphere. 
+
+    This uses the standard mathematical calculation: 
+
+    $4\pi r ^2$
+
     float : the surface area of the sphere
     """
     surface_area = 4 * pi * r **2