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/* |
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* Copyright (c) 2005 The University of Notre Dame. All Rights Reserved. |
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* |
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* The University of Notre Dame grants you ("Licensee") a |
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* non-exclusive, royalty free, license to use, modify and |
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* redistribute this software in source and binary code form, provided |
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* that the following conditions are met: |
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* |
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* 1. Acknowledgement of the program authors must be made in any |
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* publication of scientific results based in part on use of the |
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* program. An acceptable form of acknowledgement is citation of |
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* the article in which the program was described (Matthew |
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* A. Meineke, Charles F. Vardeman II, Teng Lin, Christopher |
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* J. Fennell and J. Daniel Gezelter, "OOPSE: An Object-Oriented |
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* Parallel Simulation Engine for Molecular Dynamics," |
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* J. Comput. Chem. 26, pp. 252-271 (2005)) |
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* |
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* 2. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* 3. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the |
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* distribution. |
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* |
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* This software is provided "AS IS," without a warranty of any |
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* kind. All express or implied conditions, representations and |
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* warranties, including any implied warranty of merchantability, |
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* fitness for a particular purpose or non-infringement, are hereby |
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* excluded. The University of Notre Dame and its licensors shall not |
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* be liable for any damages suffered by licensee as a result of |
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* using, modifying or distributing the software or its |
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* derivatives. In no event will the University of Notre Dame or its |
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* licensors be liable for any lost revenue, profit or data, or for |
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* direct, indirect, special, consequential, incidental or punitive |
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* damages, however caused and regardless of the theory of liability, |
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* arising out of the use of or inability to use software, even if the |
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* University of Notre Dame has been advised of the possibility of |
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* such damages. |
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*/ |
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|
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#include <stdio.h> |
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#include <cmath> |
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|
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#include "math/RealSphericalHarmonic.hpp" |
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|
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using namespace oopse; |
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|
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RealSphericalHarmonic::RealSphericalHarmonic() { |
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} |
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|
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double RealSphericalHarmonic::getValueAt(double costheta, double phi) { |
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|
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double p, phase; |
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|
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// associated Legendre polynomial |
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p = LegendreP(L,M,costheta); |
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|
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if (functionType == RSH_SIN) { |
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phase = sin((double)M * phi); |
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} else { |
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phase = cos((double)M * phi); |
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} |
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|
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return coefficient*p*phase; |
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|
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} |
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|
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//---------------------------------------------------------------------------// |
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// |
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// double LegendreP (int l, int m, double x); |
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// |
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// Computes the value of the associated Legendre polynomial P_lm (x) |
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// of order l at a given point. |
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// |
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// Input: |
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// l = degree of the polynomial >= 0 |
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// m = parameter satisfying 0 <= m <= l, |
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// x = point in which the computation is performed, range -1 <= x <= 1. |
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// Returns: |
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// value of the polynomial in x |
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// |
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//---------------------------------------------------------------------------// |
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double RealSphericalHarmonic::LegendreP (int l, int m, double x) { |
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// check parameters |
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if (m < 0 || m > l || fabs(x) > 1.0) { |
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printf("LegendreP got a bad argument: l = %d\tm = %d\tx = %lf\n", l, m, x); |
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return NAN; |
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} |
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|
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double pmm = 1.0; |
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if (m > 0) { |
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double h = sqrt((1.0-x)*(1.0+x)), |
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f = 1.0; |
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for (int i = 1; i <= m; i++) { |
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pmm *= -f * h; |
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f += 2.0; |
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} |
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} |
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if (l == m) |
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return pmm; |
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else { |
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double pmmp1 = x * (2 * m + 1) * pmm; |
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if (l == (m+1)) |
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return pmmp1; |
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else { |
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double pll = 0.0; |
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for (int ll = m+2; ll <= l; ll++) { |
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pll = (x * (2 * ll - 1) * pmmp1 - (ll + m - 1) * pmm) / (ll - m); |
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pmm = pmmp1; |
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pmmp1 = pll; |
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} |
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return pll; |
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} |
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} |
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} |
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|