Kokkos_complex.hpp

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//   Kokkos: Manycore Performance-Portable Multidimensional Arrays
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#ifndef KOKKOS_COMPLEX_HPP
#define KOKKOS_COMPLEX_HPP

#include <Kokkos_Atomic.hpp>
#include <complex>
#include <iostream>

namespace Kokkos {

template<class RealType>
class complex {
private:
  RealType re_, im_;

public:
  typedef RealType value_type;

  KOKKOS_INLINE_FUNCTION complex () :
    re_ (0.0), im_ (0.0)
  {}

  KOKKOS_INLINE_FUNCTION complex (const complex<RealType>& src) :
    re_ (src.re_), im_ (src.im_)
  {}

  template<class InputRealType>
  complex (const std::complex<InputRealType>& src) :
    re_ (std::real (src)), im_ (std::imag (src))
  {}

  operator std::complex<RealType> () const {
    return std::complex<RealType> (re_, im_);
  }

  template<class InputRealType>
  KOKKOS_INLINE_FUNCTION complex (const InputRealType& val) :
    re_ (val), im_ (0.0)
  {}

  template<class RealType1, class RealType2>
  KOKKOS_INLINE_FUNCTION complex (const RealType1& re, const RealType2& im) :
    re_ (re), im_ (im)
  {}

  template<class InputRealType>
  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator= (const complex<InputRealType>& src) {
    re_ = src.re_;
    im_ = src.im_;
    return *this;
  }

  template<class InputRealType>
  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator= (const complex<InputRealType>& src) volatile {
    re_ = src.re_;
    im_ = src.im_;
    return *this;
  }

  template<class InputRealType>
  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator= (const InputRealType& val) {
    re_ = val;
    im_ = static_cast<RealType> (0.0);
    return *this;
  }

  template<class InputRealType>
  complex<RealType>& operator= (const std::complex<InputRealType>& src) {
    re_ = std::real (src);
    im_ = std::imag (src);
    return *this;
  }

  KOKKOS_INLINE_FUNCTION RealType imag () const {
    return im_;
  }

  KOKKOS_INLINE_FUNCTION RealType real () const {
    return re_;
  }

  KOKKOS_INLINE_FUNCTION RealType imag () const volatile {
    return im_;
  }

  KOKKOS_INLINE_FUNCTION RealType real () const volatile {
    return re_;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator += (const complex<RealType>& src) {
    re_ += src.re_;
    im_ += src.im_;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  void operator += (const volatile complex<RealType>& src) volatile {
    re_ += src.re_;
    im_ += src.im_;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator += (const RealType& src) {
    re_ += src;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  void operator += (const volatile RealType& src) volatile {
    re_ += src;
  }

  KOKKOS_INLINE_FUNCTION void atomic_add (const complex<RealType>& x) volatile {
    // We can do the atomic update of a complex number componentwise,
    // since the components don't interact in an add operation.  This
    // does NOT work for dd_real!
    ::Kokkos::atomic_add (&re_, x.real ());
    ::Kokkos::atomic_add (&im_, x.imag ());
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator -= (const complex<RealType>& src) {
    re_ -= src.re_;
    im_ -= src.im_;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator -= (const RealType& src) {
    re_ -= src;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator *= (const complex<RealType>& src) {
    const RealType realPart = re_ * src.re_ - im_ * src.im_;
    const RealType imagPart = re_ * src.im_ + im_ * src.re_;
    re_ = realPart;
    im_ = imagPart;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  void operator *= (const volatile complex<RealType>& src) volatile {
    const RealType realPart = re_ * src.re_ - im_ * src.im_;
    const RealType imagPart = re_ * src.im_ + im_ * src.re_;
    re_ = realPart;
    im_ = imagPart;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator *= (const RealType& src) {
    re_ *= src;
    im_ *= src;
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  void operator *= (const volatile RealType& src) volatile {
    re_ *= src;
    im_ *= src;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator /= (const complex<RealType>& y) {
    // Scale (by the "1-norm" of y) to avoid unwarranted overflow.
    // If the real part is +/-Inf and the imaginary part is -/+Inf,
    // this won't change the result.
    const RealType s = ::fabs (real (y)) + ::fabs (imag (y));

    // If s is 0, then y is zero, so x/y == real(x)/0 + i*imag(x)/0.
    // In that case, the relation x/y == (x/s) / (y/s) doesn't hold,
    // because y/s is NaN.
    if (s == 0.0) {
      this->re_ /= s;
      this->im_ /= s;
    }
    else {
      const complex<RealType> x_scaled (this->re_ / s, this->im_ / s);
      const complex<RealType> y_conj_scaled (y.re_ / s, -(y.im_) / s);
      const RealType y_scaled_abs = y_conj_scaled.re_ * y_conj_scaled.re_ +
        y_conj_scaled.im_ * y_conj_scaled.im_; // abs(y) == abs(conj(y))
      *this = x_scaled * y_conj_scaled;
      *this /= y_scaled_abs;
    }
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  complex<RealType>& operator /= (const RealType& src) {
    re_ /= src;
    im_ /= src;
    return *this;
  }
};

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator + (const complex<RealType>& x, const complex<RealType>& y) {
  return complex<RealType> (x.real () + y.real (), x.imag () + y.imag ());
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator + (const complex<RealType>& x) {
  return x;
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator - (const complex<RealType>& x, const complex<RealType>& y) {
  return complex<RealType> (x.real () - y.real (), x.imag () - y.imag ());
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator - (const complex<RealType>& x) {
  return complex<RealType> (-x.real (), -x.imag ());
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator * (const complex<RealType>& x, const complex<RealType>& y) {
  return complex<RealType> (x.real () * y.real () - x.imag () * y.imag (),
                            x.real () * y.imag () + x.imag () * y.real ());
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
RealType imag (const complex<RealType>& x) {
  return x.imag ();
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
RealType real (const complex<RealType>& x) {
  return x.real ();
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
RealType abs (const complex<RealType>& x) {
  // FIXME (mfh 31 Oct 2014) Scale to avoid unwarranted overflow.
  return ::sqrt (real (x) * real (x) + imag (x) * imag (x));
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType> conj (const complex<RealType>& x) {
  return complex<RealType> (real (x), -imag (x));
}


template<class RealType1, class RealType2>
KOKKOS_INLINE_FUNCTION
complex<RealType1>
operator / (const complex<RealType1>& x, const RealType2& y) {
  return complex<RealType1> (real (x) / y, imag (x) / y);
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
complex<RealType>
operator / (const complex<RealType>& x, const complex<RealType>& y) {
  // Scale (by the "1-norm" of y) to avoid unwarranted overflow.
  // If the real part is +/-Inf and the imaginary part is -/+Inf,
  // this won't change the result.
  const RealType s = ::fabs (real (y)) + ::fabs (imag (y));

  // If s is 0, then y is zero, so x/y == real(x)/0 + i*imag(x)/0.
  // In that case, the relation x/y == (x/s) / (y/s) doesn't hold,
  // because y/s is NaN.
  if (s == 0.0) {
    return complex<RealType> (real (x) / s, imag (x) / s);
  }
  else {
    const complex<RealType> x_scaled (real (x) / s, imag (x) / s);
    const complex<RealType> y_conj_scaled (real (y) / s, -imag (y) / s);
    const RealType y_scaled_abs = real (y_conj_scaled) * real (y_conj_scaled) +
      imag (y_conj_scaled) * imag (y_conj_scaled); // abs(y) == abs(conj(y))
    complex<RealType> result = x_scaled * y_conj_scaled;
    result /= y_scaled_abs;
    return result;
  }
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
bool operator == (const complex<RealType>& x, const complex<RealType>& y) {
  return real (x) == real (y) && imag (x) == imag (y);
}

template<class RealType1, class RealType2>
KOKKOS_INLINE_FUNCTION
bool operator == (const complex<RealType1>& x, const RealType2& y) {
  return real (x) == y && imag (x) == static_cast<RealType1> (0.0);
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
bool operator == (const RealType& x, const complex<RealType>& y) {
  return y == x;
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
bool operator != (const complex<RealType>& x, const complex<RealType>& y) {
  return real (x) != real (y) || imag (x) != imag (y);
}

template<class RealType1, class RealType2>
KOKKOS_INLINE_FUNCTION
bool operator != (const complex<RealType1>& x, const RealType2& y) {
  return real (x) != y || imag (x) != static_cast<RealType1> (0.0);
}

template<class RealType>
KOKKOS_INLINE_FUNCTION
bool operator != (const RealType& x, const complex<RealType>& y) {
  return y != x;
}

template<class RealType>
std::ostream& operator << (std::ostream& os, const complex<RealType>& x) {
  const std::complex<RealType> x_std (Kokkos::real (x), Kokkos::imag (x));
  os << x_std;
  return os;
}

template<class RealType>
std::ostream& operator >> (std::ostream& os, complex<RealType>& x) {
  std::complex<RealType> x_std;
  os >> x_std;
  x = x_std; // only assigns on success of above
  return os;
}

KOKKOS_INLINE_FUNCTION void
atomic_add (volatile ::Kokkos::complex<double>* const dest,
            const ::Kokkos::complex<double> src)
{
  dest->atomic_add (src);
}

} // namespace Kokkos

#endif // KOKKOS_COMPLEX_HPP