betainc.h

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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Covered Software is provided under this License on an "as is"
 * basis, without warranty of any kind, either expressed, implied, or
 * statutory, including, without limitation, warranties that the
 * Covered Software is free of defects, merchantable, fit for a
 * particular purpose or non-infringing.
 * See the Mozilla Public License v. 2.0 for more details.
 *
 * For more details, see http://www.mrtrix.org/.
 */
 
#ifndef __math_betainc_h__
#define __math_betainc_h__
 
#ifdef MRTRIX_HAVE_EIGEN_UNSUPPORTED_SPECIAL_FUNCTIONS
#include <unsupported/Eigen/SpecialFunctions>
#endif
 
#include <math.h>
#include "types.h"
 
 
namespace MR
{
  namespace Math
  {
 
 
 
#ifdef MRTRIX_HAVE_EIGEN_UNSUPPORTED_SPECIAL_FUNCTIONS
 
    // Compute the *regularised* incomplete beta function using
    //   the incomplete beta function as provided in Eigen 3.3 and above
    template <typename ArgADerived, typename ArgBDerived, typename ArgXDerived>
    inline const Eigen::Array<typename ArgXDerived::Scalar, Eigen::Dynamic, Eigen::Dynamic>
    betaincreg (const Eigen::ArrayBase<ArgADerived>& a, const Eigen::ArrayBase<ArgBDerived>& b, const Eigen::ArrayBase<ArgXDerived>& x)
    {
      Eigen::Array<typename ArgXDerived::Scalar, Eigen::Dynamic, Eigen::Dynamic> ones (x);
      ones.fill (typename ArgXDerived::Scalar (1));
      return (Eigen::betainc (a, b, x) / Eigen::betainc (a, b, ones)).eval();
    };
 
#endif
 
 
 
 
    default_type betaincreg (const default_type a, const default_type b, const default_type x);
 
 
 
  }
}
 
#endif