Source Code for Module ComboCode.cc.tools.numerical.Operators

 1  # -*- coding: utf-8 -*- 
 2   
 3  """ 
 4  Module with several methods that function as operators for numerical grids. 
 5   
 6  """ 
 7   
 8  import numpy as np 
 9   
10 -def diff_central(y,x): 
11   
12      ''' 
13      Calculate the numerical central difference of a function with respect to a 
14      single variable.  
15       
16      This is essentially what np.gradient does, but allows a non-equidistant  
17      independent variable. 
18       
19      @param x: The independent variable 
20      @type x: array 
21      @param y: The variable dependent on x 
22      @type y: array 
23       
24      @return: diff_central(y)/diff_central(x) 
25      @rtype: array 
26   
27      ''' 
28       
29      z1 = np.hstack((y[0], y[:-1])) 
30      z2 = np.hstack((y[1:], y[-1])) 
31      dx1 = np.hstack((0, np.diff(x))) 
32      dx2 = np.hstack((np.diff(x), 0)) 
33      return (z2-z1) / (dx2+dx1) 
34