// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2016 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// 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/.

#ifndef EIGEN_SPECIALFUNCTIONS_ARRAYAPI_H
#define EIGEN_SPECIALFUNCTIONS_ARRAYAPI_H

namespace Eigen {

/** \cpp11 \returns an expression of the coefficient-wise igamma(\a a, \a x) to
 * the given arrays.
  *
  * This function computes the coefficient-wise incomplete gamma function.
  *
  * \note This function supports only float and double scalar types in c++11
 * mode. To support other scalar types,
  * or float/double in non c++11 mode, the user has to provide implementations
 * of igammac(T,T) for any scalar
  * type T to be supported.
  *
  * \sa Eigen::igammac(), Eigen::lgamma()
  */
template <typename Derived, typename ExponentDerived>
inline const Eigen::CwiseBinaryOp<
    Eigen::internal::scalar_igamma_op<typename Derived::Scalar>, const Derived,
    const ExponentDerived>
igamma(const Eigen::ArrayBase<Derived>& a,
       const Eigen::ArrayBase<ExponentDerived>& x) {
  return Eigen::CwiseBinaryOp<
      Eigen::internal::scalar_igamma_op<typename Derived::Scalar>,
      const Derived, const ExponentDerived>(a.derived(), x.derived());
}

/** \cpp11 \returns an expression of the coefficient-wise igammac(\a a, \a x) to
 * the given arrays.
  *
  * This function computes the coefficient-wise complementary incomplete gamma
 * function.
  *
  * \note This function supports only float and double scalar types in c++11
 * mode. To support other scalar types,
  * or float/double in non c++11 mode, the user has to provide implementations
 * of igammac(T,T) for any scalar
  * type T to be supported.
  *
  * \sa Eigen::igamma(), Eigen::lgamma()
  */
template <typename Derived, typename ExponentDerived>
inline const Eigen::CwiseBinaryOp<
    Eigen::internal::scalar_igammac_op<typename Derived::Scalar>, const Derived,
    const ExponentDerived>
igammac(const Eigen::ArrayBase<Derived>& a,
        const Eigen::ArrayBase<ExponentDerived>& x) {
  return Eigen::CwiseBinaryOp<
      Eigen::internal::scalar_igammac_op<typename Derived::Scalar>,
      const Derived, const ExponentDerived>(a.derived(), x.derived());
}

/** \cpp11 \returns an expression of the coefficient-wise polygamma(\a n, \a x)
 * to the given arrays.
  *
  * It returns the \a n -th derivative of the digamma(psi) evaluated at \c x.
  *
  * \note This function supports only float and double scalar types in c++11
 * mode. To support other scalar types,
  * or float/double in non c++11 mode, the user has to provide implementations
 * of polygamma(T,T) for any scalar
  * type T to be supported.
  *
  * \sa Eigen::digamma()
  */
// * \warning Be careful with the order of the parameters: x.polygamma(n) is
// equivalent to polygamma(n,x)
// * \sa ArrayBase::polygamma()
template <typename DerivedN, typename DerivedX>
inline const Eigen::CwiseBinaryOp<
    Eigen::internal::scalar_polygamma_op<typename DerivedX::Scalar>,
    const DerivedN, const DerivedX>
polygamma(const Eigen::ArrayBase<DerivedN>& n,
          const Eigen::ArrayBase<DerivedX>& x) {
  return Eigen::CwiseBinaryOp<
      Eigen::internal::scalar_polygamma_op<typename DerivedX::Scalar>,
      const DerivedN, const DerivedX>(n.derived(), x.derived());
}

/** \cpp11 \returns an expression of the coefficient-wise betainc(\a x, \a a, \a
 * b) to the given arrays.
  *
  * This function computes the regularized incomplete beta function (integral).
  *
  * \note This function supports only float and double scalar types in c++11
 * mode. To support other scalar types,
  * or float/double in non c++11 mode, the user has to provide implementations
 * of betainc(T,T,T) for any scalar
  * type T to be supported.
  *
  * \sa Eigen::betainc(), Eigen::lgamma()
  */
template <typename ArgADerived, typename ArgBDerived, typename ArgXDerived>
inline const Eigen::CwiseTernaryOp<
    Eigen::internal::scalar_betainc_op<typename ArgXDerived::Scalar>,
    const ArgADerived, const ArgBDerived, const ArgXDerived>
betainc(const Eigen::ArrayBase<ArgADerived>& a,
        const Eigen::ArrayBase<ArgBDerived>& b,
        const Eigen::ArrayBase<ArgXDerived>& x) {
  return Eigen::CwiseTernaryOp<
      Eigen::internal::scalar_betainc_op<typename ArgXDerived::Scalar>,
      const ArgADerived, const ArgBDerived, const ArgXDerived>(
      a.derived(), b.derived(), x.derived());
}

/** \returns an expression of the coefficient-wise zeta(\a x, \a q) to the given
 * arrays.
  *
  * It returns the Riemann zeta function of two arguments \a x and \a q:
  *
  * \param x is the exposent, it must be > 1
  * \param q is the shift, it must be > 0
  *
  * \note This function supports only float and double scalar types. To support
 * other scalar types, the user has
  * to provide implementations of zeta(T,T) for any scalar type T to be
 * supported.
  *
  * \sa ArrayBase::zeta()
  */
template <typename DerivedX, typename DerivedQ>
inline const Eigen::CwiseBinaryOp<
    Eigen::internal::scalar_zeta_op<typename DerivedX::Scalar>, const DerivedX,
    const DerivedQ>
zeta(const Eigen::ArrayBase<DerivedX>& x, const Eigen::ArrayBase<DerivedQ>& q) {
  return Eigen::CwiseBinaryOp<
      Eigen::internal::scalar_zeta_op<typename DerivedX::Scalar>,
      const DerivedX, const DerivedQ>(x.derived(), q.derived());
}

}  // end namespace Eigen

#endif  // EIGEN_SPECIALFUNCTIONS_ARRAYAPI_H