From 96b0d6a38cd28cc0a03df229f0020517da16ba80 Mon Sep 17 00:00:00 2001
From: Lindsey <lindseyheagy@gmail.com>
Date: Mon, 4 May 2015 16:48:57 -0700
Subject: [PATCH] added def of k to utils and have getSourceDeriv take fields
 and vector

---
 simpegEM/FDEM/FDEM.py     | 2 +-
 simpegEM/Utils/EMUtils.py | 9 +++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/simpegEM/FDEM/FDEM.py b/simpegEM/FDEM/FDEM.py
index a21b8b9e..72dca5eb 100644
--- a/simpegEM/FDEM/FDEM.py
+++ b/simpegEM/FDEM/FDEM.py
@@ -125,7 +125,7 @@ class BaseFDEMProblem(BaseEMProblem):
 
         return S_m, S_e
 
-    def getSourceDeriv(self,freq,adjoint=False):
+    def getSourceDeriv(self,freq,m,v,u=None,adjoint=False):
         raise NotImplementedError('getSourceDeriv not implemented yet')
         return None, None
 
diff --git a/simpegEM/Utils/EMUtils.py b/simpegEM/Utils/EMUtils.py
index 9d80728f..edd1d247 100644
--- a/simpegEM/Utils/EMUtils.py
+++ b/simpegEM/Utils/EMUtils.py
@@ -1,5 +1,10 @@
 import numpy as np
+from scipy.constants import mu_0, epsilon_0
 
 def omega(freq):
-    """Change frequency to angular frequency, omega"""
-    return 2.*np.pi*freq
\ No newline at end of file
+    """Angular frequency, omega"""
+    return 2.*np.pi*freq
+
+def k(freq, sigma, mu=mu_0, eps=epsilon_0):
+	w = omega(freq)
+	return np.sqrt(mu * eps * w**2 - 1j * w* mu * sigma)
\ No newline at end of file