r8701 - /branches/ave_noe/maths_fns/potential.py -- January 29, 2009 - 16:40

Author: bugman
Date: Thu Jan 29 16:40:07 2009
New Revision: 8701

URL: http://svn.gna.org/viewcvs/relax?rev=8701&view=rev
Log:
Created a module for calculating different optimisation/energy potentials.

The function quad_pot() has been written to provide a flat-bottom potential.


Added:
    branches/ave_noe/maths_fns/potential.py

Added: branches/ave_noe/maths_fns/potential.py
URL: 
http://svn.gna.org/viewcvs/relax/branches/ave_noe/maths_fns/potential.py?rev=8701&view=auto
==============================================================================
--- branches/ave_noe/maths_fns/potential.py (added)
+++ branches/ave_noe/maths_fns/potential.py Thu Jan 29 16:40:07 2009
@@ -1,0 +1,66 @@
+###############################################################################
+#                                                                            
 #
+# Copyright (C) 2009 Edward d'Auvergne                                       
 #
+#                                                                            
 #
+# This file is part of the program relax.                                    
 #
+#                                                                            
 #
+# relax is free software; you can redistribute it and/or modify              
 #
+# it under the terms of the GNU General Public License as published by       
 #
+# the Free Software Foundation; either version 2 of the License, or          
 #
+# (at your option) any later version.                                        
 #
+#                                                                            
 #
+# relax is distributed in the hope that it will be useful,                   
 #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of             
 #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              
 #
+# GNU General Public License for more details.                               
 #
+#                                                                            
 #
+# You should have received a copy of the GNU General Public License          
 #
+# along with relax; if not, write to the Free Software                       
 #
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  
 #
+#                                                                            
 #
+###############################################################################
+
+# Module docstring.
+"""Functions for calculating various optimisation potentials."""
+
+
+def quad_pot(values, pot, lower, upper):
+    """Calculate the flat-bottom quadratic energy potential.
+
+    The formula used is::
+
+                            / (x - x+)^2    if x > x+,
+                            |                         
+        V_pQuad(x;x+,x-) = <  (x - x-)^2    if x < x-,
+                            |                         
+                            \ 0             otherwise.
+
+    Where x+ and x- are the absolute bounds.
+
+
+    @param values:  An array of values of x.
+    @type values:   numpy float array
+    @param pot:     The array to place the potential values (V_pQuad) into.  
This should have the
+                    same dimensions as the values array.
+    @type pot:      numpy float array
+    @param lower:   The array of lower bounds.  This should have the same 
dimensions as the values
+                    array.
+    @type lower:    numpy float array
+    @param upper:   The array of upper bounds.  This should have the same 
dimensions as the values
+                    array.
+    @type upper:    numpy float array
+    """
+
+    # Loop over the x values.
+    for i in xrange(len(values)):
+        # First condition.
+        if values[i] > upper[i]:
+            pot[i] = (values[i] - upper[i])**2
+
+        # Second contition.
+        elif values[i] < lower[i]:
+            pot[i] = (values[i] - lower[i])**2
+
+        # Otherwise clear the array element.
+        else:
+            pot[i] = 0.0