ClebschGordan.h

/*  YAP - Yet another PWA toolkit
    Copyright 2015, Technische Universitaet Muenchen,
    Authors: Daniel Greenwald, Johannes Rauch

    This program 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 3 of the License, or
    (at your option) any later version.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef yap_ClebschGordan_h
#define yap_ClebschGordan_h

#include <cstdlib>
#include <string>

namespace yap {

namespace ClebschGordan {

std::string to_string(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J, int two_M);

inline std::string to_string(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J)
{ return to_string(two_j1, two_m1, two_j2, two_m2, two_J, two_m1 + two_m2); }

const bool nonzeroCoefficient(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J, int two_M);

inline const bool nonzeroCoefficient(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J)
{ return nonzeroCoefficient(two_j1, two_m1, two_j2, two_m2, two_J, two_m1 + two_m2); }

const double coefficient(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J, int two_M);

inline const double coefficient(unsigned two_j1, int two_m1, unsigned two_j2, int two_m2, unsigned two_J)
{ return coefficient(two_j1, two_m1, two_j2, two_m2, two_J, two_m1 + two_m2); }

inline const bool nonzeroCoupling(unsigned two_j1, int two_lambda1, unsigned two_j2, int two_lambda2, unsigned l, unsigned two_s, unsigned two_J)
{ return nonzeroCoefficient(2 * l, 0, two_s, two_lambda1 - two_lambda2, two_J) and nonzeroCoefficient(two_j1, two_lambda1, two_j2, -two_lambda2, two_s); }

double const couple(unsigned two_j1, int two_lambda1, unsigned two_j2, int two_lambda2, unsigned l, unsigned two_s, unsigned two_J);

const bool consistent(unsigned two_J, int two_M);

} // ClebschGordon namespace

} // yap namespace

#endif