From 3f224662bad9251dc24a440a084adf110bad57c1 Mon Sep 17 00:00:00 2001
From: craig-warren <craig_warren@me.com>
Date: Sat, 6 Feb 2016 10:22:48 +0000
Subject: [PATCH] Added function to find zero crossings of signal.

---
 gprMax/utilities.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/gprMax/utilities.py b/gprMax/utilities.py
index a6a1a28c..26588e1d 100644
--- a/gprMax/utilities.py
+++ b/gprMax/utilities.py
@@ -128,3 +128,18 @@ def human_size(size, a_kilobyte_is_1024_bytes=True):
     raise ValueError('Number is too large.')
 
 
+def zero_crossings(data):
+    """Find location of zero crossings in 1D data array.
+        
+    Args:
+        data (float): 1D array
+        
+    Returns:
+        Array of indices (int).
+    """
+    
+    pos = data > 0
+    npos = ~pos
+    return ((pos[:-1] & npos[1:]) | (npos[:-1] & pos[1:])).nonzero()[0]
+
+