fix docstrings

Author: wholmgren

pvlib/solarposition.py

@@ -775,7 +775,8 @@ def pyephem_earthsun_distance(time):
 
 def nrel_earthsun_distance(time, how='numpy', delta_t=None, numthreads=4):
     """
-    Calculates the distance from the earth to the sun using pyephem.
+    Calculates the distance from the earth to the sun using the
+    NREL SPA algorithm described in [1].
 
     Parameters
     ----------
@@ -797,6 +798,12 @@ def nrel_earthsun_distance(time, how='numpy', delta_t=None, numthreads=4):
     -------
     R : pd.Series
         Earth-sun distance in AU.
+
+    References
+    ----------
+    [1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
+    radiation applications. Technical report: NREL/TP-560- 34302. Golden,
+    USA, http://www.nrel.gov.
     """
     delta_t = delta_t or 67.0
 

pvlib/spa.py

@@ -1267,8 +1267,8 @@ def transit_sunrise_sunset(dates, lat, lon, delta_t, numthreads):
 
 def earthsun_distance(unixtime, delta_t, numthreads):
     """
-    Calculate the sun transit, sunrise, and sunset
-    for a set of dates at a given location.
+    Calculates the distance from the earth to the sun using the
+    NREL SPA algorithm described in [1].
 
     Parameters
     ----------
@@ -1285,6 +1285,12 @@ def earthsun_distance(unixtime, delta_t, numthreads):
     -------
     R : array
         Earth-Sun distance in AU.
+
+    References
+    ----------
+    [1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
+    radiation applications. Technical report: NREL/TP-560- 34302. Golden,
+    USA, http://www.nrel.gov.
     """
 
     R = solar_position(unixtime, 0, 0, 0, 0, 0, delta_t,