Index: /issm/trunk-jpl/src/m/classes/esa.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/esa.py	(revision 21649)
+++ /issm/trunk-jpl/src/m/classes/esa.py	(revision 21650)
@@ -2,4 +2,5 @@
 from MatlabFuncs import *
 from model import *
+import numpy as np
 from checkfield import checkfield
 from WriteData import WriteData
@@ -14,5 +15,5 @@
 	
 	def __init__(self): # {{{
-		self.deltathickness    = NaN
+		self.deltathickness    = np.nan
 		self.love_h            = 0 #provided by PREM model()
 		self.love_l            = 0 #ideam