r11427 - /1.3/maths_fns/coord_transform.py -- August 06, 2010 - 11:29

Author: bugman
Date: Fri Aug  6 11:29:23 2010
New Revision: 11427

URL: http://svn.gna.org/viewcvs/relax?rev=11427&view=rev
Log:
Created a new module for performing coordinate transformations.

The new function cartesian_to_spherical() has been added as the first 
conversion.


Added:
    1.3/maths_fns/coord_transform.py

Added: 1.3/maths_fns/coord_transform.py
URL: 
http://svn.gna.org/viewcvs/relax/1.3/maths_fns/coord_transform.py?rev=11427&view=auto
==============================================================================
--- 1.3/maths_fns/coord_transform.py (added)
+++ 1.3/maths_fns/coord_transform.py Fri Aug  6 11:29:23 2010
@@ -1,0 +1,57 @@
+###############################################################################
+#                                                                            
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+# Copyright (C) 2010 Edward d'Auvergne                                       
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+#                                                                            
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+# This file is part of the program relax.                                    
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+#                                                                            
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+# relax is free software; you can redistribute it and/or modify              
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+# it under the terms of the GNU General Public License as published by       
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+# the Free Software Foundation; either version 2 of the License, or          
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+# (at your option) any later version.                                        
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+#                                                                            
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+# relax is distributed in the hope that it will be useful;                   
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+# but WITHOUT ANY WARRANTY; without even the implied warranty of             
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+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              
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+# GNU General Public License for more details.                               
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+#                                                                            
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+# You should have received a copy of the GNU General Public License          
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+# along with relax; if not, write to the Free Software                       
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+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  
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+#                                                                            
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+###############################################################################
+
+# Module docstring.
+"""Module for transforming between different coordinate systems."""
+
+# Python module imports.
+from math import acos, atan2
+from numpy import array, float64
+from numpy.linalg import norm
+
+
+def cartesian_to_spherical(vector):
+    """Convert the Cartesian vector [x, y, z] to spherical coordinates [r, 
phi, theta].
+
+    The parameter r is the radial distance, phi is the polar angle, and 
theta is the azimuth.
+
+
+    @param vector:  The Cartesian vector [x, y, z].
+    @type vector:   numpy rank-1, 3D array
+    @return:        The spherical coordinate vector [r, phi, theta].
+    @rtype:         numpy rank-1, 3D array
+    """
+
+    # The radial distance.
+    r = norm(vector)
+
+    # Unit vector.
+    unit = vector / r
+
+    # The polar angle.
+    phi = acos(unit[2])
+
+    # The azimuth.
+    theta = atan2(unit[1], unit[0])
+
+    # Return the spherical coordinate vector.
+    return array([r, phi, theta], float64)