Source Code for Module lib.curve_fit.exponential

 1  ############################################################################### 
 2  #                                                                             # 
 3  # Copyright (C) 2013 Edward d'Auvergne                                        # 
 4  #                                                                             # 
 5  # This file is part of the program relax (http://www.nmr-relax.com).          # 
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 7  # This program is free software: you can redistribute it and/or modify        # 
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15  # GNU General Public License for more details.                                # 
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18  # along with this program.  If not, see <http://www.gnu.org/licenses/>.       # 
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20  ############################################################################### 
21   
22  # Module docstring. 
23  """Module for exponential curve-fitting.""" 
24   
25  # Python module imports. 
26  from math import exp 
27   
28   
29 -def exponential_2param_neg(rate=None, i0=None, x=None, y=None): 
30      """Calculate the data for a standard two parameter decreasing exponential. 
31   
32      The y-values will be calculated based on the x-values. 
33   
34   
35      @keyword rate:  The exponential rate. 
36      @type rate:     float 
37      @keyword i0:    The initial intensity. 
38      @type i0:       float 
39      @keyword x:     The x-values at which to calculate the y-values. 
40      @type x:        numpy rank-1 float array 
41      @keyword y:     The data structure to store the y-values in. 
42      @type y:        numpy rank-1 float array 
43      """ 
44   
45      # Loop over the x-values. 
46      for i in range(len(x)): 
47          y[i] = i0 * exp(-rate*x[i]) 
48