cmplx.h

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/**
 * @file cmplx.h
 * @brief Definition of Complex types
 * @details This file contains definitions and methods for Complex numbers and Imaginary type.
 *
 * > NOTE: All overloads for operators +,-,/,* are not documented separately since there exists a
 * > function for each combinations of scalar,imaginary and complex number representations. All
 * > versions are documented in the Complex -- Complex definitions.
 *
 */
 
#ifndef CMPLX_H_
#define CMPLX_H_
 
// let's not include the std::complex
// #include <complex>
// #include <cmath>
 
#include "plumbing/defs.h"
 
// TEMPORARY location for vector intrinsic analogues -- result obvious
 
template <typename T, std::enable_if_t<hila::is_arithmetic<T>::value, int> = 0>
inline T mul_add(T a, T b, T c) {
    return a * b + c;
}
 
template <typename T, std::enable_if_t<hila::is_arithmetic<T>::value, int> = 0>
inline T mul_sub(T a, T b, T c) {
    return a * b - c;
}
 
template <typename T, std::enable_if_t<hila::is_arithmetic<T>::value, int> = 0>
inline T nmul_add(T a, T b, T c) {
    return c - a * b;
}
 
/**
 * @brief Complex definition
 * @details Define complex type as a class. This allows Hilapp to replace the internal type with
 * a vector.
 *
 * __NOTE:__ T must be arithmetic and integrable. In the following documentation MyType refers to T,
 * as in an arithmetic and integrable type.
 * @param re Real part
 * @param im Imaginary part
 * @tparam T Arithmetic type
 */
template <typename T>
class Complex {
 
    static_assert((hila::is_arithmetic<T>::value && !std::is_integral<T>::value),
                  "Complex can be used only with floating point type");
    // This incantation is needed to make Field<Complex<>> vectorized
 
  public:
    using base_type = hila::arithmetic_type<T>;
    using argument_type = T;
 
    // and the content of the complex number
    T re, im;
 
    /**
     * @brief Default constructo
     * @details
     *
     * \code{.cpp}
     * Complex<MyType> C;
     * \endcode
     *
     * The default constructor initializes \p Complex#re and \p Complex#im to 0
     *
     */
    Complex<T>() = default;
    ~Complex<T>() = default;
 
 
    /**
     * @brief Copy constructor
     *
     * Initialize form already existing Complex number
     *
     * \code {.cpp}
     * MyType a,b;
     * a = hila::random();
     * b = hila::random();
     * Complex<MyType> C(a,b);
     * Complex<MyType> B = C; // B.re = a, B.im = b
     * \endcode
     *
     * Equivalent initializing is `Complex<MyType> B(C)`
     * @param a
     */
    Complex<T>(const Complex<T> &a) = default;
 
    // constructor from single complex --IS THIS NEEDED?
    // template <typename A,
    //           std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0 >
    // constexpr Complex<T>(const Complex<A> a) : re(static_cast<T>(a.re)),
    // im(static_cast<T>(a.im)) {}
 
    // constructor from single scalar value
    // Remember to mark this explicit, we do not want this to be invoked
    // in automatic conversions (there should be methods)
 
    //#pragma hila loop_function
    /**
     * @brief Real constructor
     *
     * Initialize only real element and sets imaginary to 0
     *
     * \code {.cpp}
     * MyType a = hila::random();
     * Complex<MyType> C(a); // C.re = a, C.im = 0
     * \endcode
     *
     * Not equivalent to `Complex<MyType> C = a`
     * @tparam S Type for value val
     */
    template <typename S, std::enable_if_t<hila::is_arithmetic<S>::value, int> = 0>
    explicit constexpr Complex<T>(const S val) : re(val), im(0) {}
 
    /**
     * @brief Zero constructor
     *
     * Initialize to zero with nullpointer trick
     *
     * \code {.cpp}
     * Complex<MyType> C = 0; // C.re = 0, C.im = 0
     * \endcode
     *
     * Equivalent to `Complex<MyType> C` and `Complex<MyType> C(0)`
     * @internal
     */
    constexpr Complex<T>(const std::nullptr_t n) : re(0), im(0) {}
 
    // constructor c(a,b)
    /**
     * @brief Complex constructor
     *
     * Initialize both real and imaginary element
     *
     * \code{.cpp}
     * MyType a,b;
     * a = hila::random();
     * b = hila::random();
     * Complex<MyType> C(a,b); // C.re = a, C.im = b
     * \endcode
     *
     * @tparam A Type for value a
     * @tparam B Type for value b
     */
    template <typename A, typename B, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0,
              std::enable_if_t<hila::is_arithmetic<B>::value, int> = 0>
    explicit constexpr Complex<T>(const A &a, const B &b) : re(a), im(b) {}
 
    // make also std accessors real() and imag() - don't return reference, because
    // v.real() would not then work inside loops!
 
 
    /**
     * @brief Real part of Complex number
     * @details Pass by value if Complex number is defined as const
     *
     * @return T Real part
     */
    inline T real() const {
        return re;
    }
    /**
     * @brief Imaginary part of Complex number
     * @details Pass by value if Complex number is defined as const
     * @return T Imaginary part
     */
    inline T imag() const {
        return im;
    }
 
    /**
     * @brief Real part of Complex number
     * @details Pass by reference
     *
     * @return T & Real part
     */
    inline T &real() const_function {
        return re;
    }
    /**
     * @brief Imaginary part of Complex number
     * @details Pass by reference
     *
     * @return T & Imaginary part
     */
    inline T &imag() const_function {
        return im;
    }
    // automatic casting from Complex<T> -> Complex<A>
    // TODO: ensure this works if A is vector type!
    template <typename A>
#pragma hila loop_function // TODO
    operator Complex<A>() const {
        return Complex<A>(re, im);
    }
 
    /**
     * @brief Assignment operator
     * @details The following ways of assigning a Complex object are
     *
     * __Assignment for Complex:__
     *
     * \code {.cpp}
     * Complex<MyType> C(hila::random(),hila::random());
     * Complex<MyType> B;
     * B = C; // B.re = C.re, B.im = C.im
     * \endcode
     *
     * __Assignment from real:__
     *
     * Assigns real part and imaginary part to zero
     *
     * \code {.cpp}
     * Complex<MyType> B;
     * MyType a = hila::random;
     * B = a; // B.re = a, B.im = 0
     * \endcode
     *
     * @param s
     * @return Complex<T>&
     */
    inline Complex<T> &operator=(const Complex<T> &s) = default;
 
    /**
     * @brief Assignment from complex
     *
     * \code {.cpp}
     * Complex<MyType> C(hila::random(),hila::random());
     * Complex<MyType> B;
     * B = C; // B.re = C.re, B.im = C.im
     * \endcode
     *
     * @tparam A Type for Complex value s
     * @param s Value to assign
     * @return Complex<T>&
     */
    template <typename A>
    inline Complex<T> &operator=(const Complex<A> &s) {
        re = s.re;
        im = s.im;
        return *this;
    }
 
    /**
     * @brief Assignment from real
     *
     * Assigns real part and imaginary part to zero
     *
     * \code {.cpp}
     * Complex<MyType> B;
     * MyType a = hila::random;
     * B = a; // B.re = a, B.im = 0
     * \endcode
     *
     * @tparam S Type for real value s
     * @param s Value to assign
     * @return Complex<T>&
     */
    template <typename S, std::enable_if_t<hila::is_arithmetic<S>::value, int> = 0>
    inline Complex<T> &operator=(S s) {
        re = s;
        im = 0;
        return *this;
    }
 
    /**
     * @brief Compute square norm of Complex number
     * @details
     * \f{align}{ |z|^2 = \Re(z)^2 + \Im(z)^2\f}
     *
     * @return T Squared norm
     */
    inline T squarenorm() const {
        return re * re + im * im;
    }
 
    /**
     * @brief Compute absolute value of Complex number
     * @details Essentially sqrt(squarenorm(z)):
     * \f{align}{ |z| = \sqrt{\Re(z)^2 + \Im(z)^2}\f}
     *
     * @return T
     */
    inline T abs() const {
        return sqrt(squarenorm());
    }
 
    /**
     * @brief Compute argument of Complex number
     * @details
     * \f{align}{ \arg(z) = \arctan2(\Im(z)),\Re(z)\f}
     *
     * @return T
     */
    inline T arg() const {
        return atan2(im, re);
    }
 
    /**
     * @brief Compute conjugate of Complex number
     * @details
     * \f{align}{ z &= x + i\cdot y \\
     * \Rightarrow z^* &= x - i\cdot y\f}
     *
     * @return Complex<T>
     */
    inline Complex<T> conj() const {
        return Complex<T>(re, -im);
    }
 
    /**
     * @brief Compute dagger of Complex number
     * @details Alias to Complex::conj
     *
     * \f{align}{ z^* = z^\dagger \f}
     * @return Complex<T>
     */
    inline Complex<T> dagger() const {
        return Complex<T>(re, -im);
    }
 
    /**
     * @brief Stores and returns Complex number given in polar coordinates
     *
     * \f{align}{ z = r\cdot e^{i\theta} \f}
     * \code {.cpp}
     * Complex<double> c;
     * double r = 1;
     * double theta = 3.14159265358979/2; // pi/2
     * c.polar(r,theta); // c.re = 0, c.im = 1
     * \endcode
     *
     *
     * @param r Radius of Complex number
     * @param theta Angle of complex number in radians
     * @return Complex<T> Complex number
     */
    inline Complex<T> polar(const T r, const T theta) out_only {
        re = r * cos(theta);
        im = r * sin(theta);
        return *this;
    }
 
    /**
     * @brief Assign random values to Complex real and imaginary part
     * @details Uses hila::random for both real and imaginary part
     *
     * @return Complex<T>&
     */
    inline Complex<T> &random() out_only {
        re = hila::random();
        im = hila::random();
        return *this;
    }
 
    /**
     * @brief Produces complex gaussian random values
     * @details Uses hila::gaussrand2 for both real and imaignary part
     * Assigns same random value for both real and imaginary part
     * @param width gaussian_random
     * @return Complex<T>&
     */
    inline Complex<T> &gaussian_random(double width = 1.0) out_only {
        double d;
        re = hila::gaussrand2(d) * width;
        im = d * width;
        return *this;
    }
 
    /**
     * @brief Unary + operator
     * @details Identity operation
     *
     * \code {.cpp}
     * Complex<MyType> z;
     * z == +z;
     * \endcode
     *
     * @return Complex<Tr>
     */
    inline Complex<T> operator+() const {
        return *this;
    }
 
    /**
     * @brief Unary - operator
     * @details Negates Complex number
     *
     * \code {.cpp}
     * Complex<MyType> z;
     * z = -z; // Results in -Re.z and -Im.z
     * \endcode
     *
     * @return Complex<T>
     */
    inline Complex<T> operator-() const {
        return Complex<T>(-re, -im);
    }
 
    // mark += and *= as loop_functions, because these can be used
    // in reductions implicitly
 
    /**
     * @brief Complex addition assignment operator
     * @details
     *
     * \code{.cpp}
     * Complex<double> z(0,0);
     * Complex<double> w(1,1);
     * z += w; // z.re = 1, z.im = 1
     * \endcode
     *
     * @tparam A Typpe of Complex number to add
     * @param lhs Complex number to add
     * @return Complex<T>&
     */
    template <typename A>
    inline Complex<T> &operator+=(const Complex<A> &lhs) {
        re += lhs.re;
        im += lhs.im;
        return *this;
    }
 
    /**
     * @brief Real addition assignment operator
     *
     * Add assign only to real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(0,0);
     * z += 1; // z.re = 1, z.im = 0
     * \endcode
     *
     * @tparam A Type for real value a
     * @param a Real value to add
     * @return Complex<T>&
     */
    template <typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
    inline Complex<T> &operator+=(const A &a) {
        re += a;
        return *this;
    }
 
    /**
     * @brief Complex subtraction assignment operator
     * @details
     *
     * \code{.cpp}
     * Complex<double> z(0,0);
     * Complex<double> w(1,1);
     * z -= w; // z.re = -1, z.im = -1
     * \endcode
     *
     * @tparam A Type for complex number to subtract
     * @param lhs Complex number to subtract
     * @return Complex<T>&
     */
    template <typename A>
    inline Complex<T> &operator-=(const Complex<A> &lhs) {
        re -= lhs.re;
        im -= lhs.im;
        return *this;
    }
 
    /**
     * @brief Real subtraction assignment operator
     * Subtract assign only to real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(0,0);
     * z -= 1; // z.re = -1, z.im = 0
     * \endcode
     *
     * @tparam A Type for real value a
     * @param a Real value to subtract
     * @return Complex<T>&
     */
    template <typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
    inline Complex<T> &operator-=(const A &a) {
        re -= a;
        return *this;
    }
 
    // inline Complex<T> & operator*= (const Complex<T> & lhs) {
    //   T r = re * lhs.re - im * lhs.im;
    //   im  = im * lhs.re + re * lhs.im;
    //   re = r;
    //   return *this;
    // }
 
    /**
     * @brief Complex multiply assignment operator
     * @details
     * Standard Complex number multiplication
     *
     * \f{align}{z &= x + iy, w = x' + iy' \\
     * z w &= (x + iy)(x' + iy') = (xx'-yy') + i(xy' + yx')\f}
     * \code{.cpp}
     * Complex<double> z,w;
     * //
     * // z,w get values
     * //
     * z*=w; // z = zw as defined above
     * \endcode
     *
     * @tparam A Type for Complex number multiply
     * @param lhs Complex number to multiply
     * @return Complex<T>&
     */
    //#pragma hila loop_function
 
    template <typename A>
    inline Complex<T> &operator*=(const Complex<A> &lhs) {
        T r = mul_sub(re, lhs.re, im * lhs.im); // a*b-c
        im = mul_add(im, lhs.re, re * lhs.im);  // a*b+c
        re = r;
        return *this;
    }
 
    /**
     * @brief Real multiply assign operator
     * @details Multiply assign by real number to both components of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(1,1);
     * z *= 2; // z.re = 2, z.im = 2
     * \endcode
     * @tparam A Type for real value a
     * @param a  Real value to multiply
     * @return Complex<T>&
     */
    template <typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
    inline Complex<T> &operator*=(const A a) {
        re *= a;
        im *= a;
        return *this;
    }
 
    // a/b = a b*/|b|^2 = (a.re*b.re + a.im*b.im + i(a.im*b.re - a.re*b.im))/|b|^2
    // inline Complex<T> & operator/= (const Complex<T> & lhs) {
    //   T n = lhs.squarenorm();
    //   T r = (re * lhs.re + im * lhs.im)/n;
    //   im  = (im * lhs.re - re * lhs.im)/n;
    //   re = r;
    //   return *this;
    // }
 
    /**
     * @brief Complex divide assignment operator
     * @details
     *
     * Standard Complex number division
     *
     * \f{align}{z &= x + iy, w = x' + iy' \\
     * \frac{z}{w} &= \frac{x + iy}{x' + iy'} = \frac{(xx'+ yy') + i( yx' - xy')}{|w|^2}\f}
     * \code{.cpp}
     * Complex<double> z,w;
     * //
     * // z,w get values
     * //
     * z/=w; // z = z/w as defined above
     * \endcode
     *
     * @tparam A Type for Complex number divide
     * @param lhs Complex number to divide
     * @return Complex<T>&
     */
    template <typename A>
    inline Complex<T> &operator/=(const Complex<A> &lhs) {
        T n = lhs.squarenorm();
        T r = mul_add(re, lhs.re, im * lhs.im) / n; // a*b+c
        im = mul_sub(im, lhs.re, re * lhs.im) / n;  // a*b-c
        re = r;
        return *this;
    }
 
    /**
     * @brief Real divide assignment operator
     * @details Divide assign by real number to both components of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(2,2);
     * z /= 2; // z.re = 1, z.im = 1
     * \endcode
     * @tparam A Type for real value to divide
     * @param a Real value to divide
     * @return Complex<T>&
     */
    template <typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
    inline Complex<T> &operator/=(const A &a) {
        re /= a;
        im /= a;
        return *this;
    }
 
    // define also increment and decrement operators (though not so intuitive for complex)
 
    /**
     * @brief Single increment operator
     *
     * Increments real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(1,1);
     * z++; // z.re = 2, z.im = 1
     * \endcode
     *
     *
     * @return Complex<T>&
     */
    inline Complex<T> &operator++() {
        this->re++;
        return *this;
    }
    /**
     * @brief Single decrement operator
     *
     * Decrement real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(1,1);
     * z--; // z.re = 0, z.im = 1
     * \endcode
     *
     *
     * @return Complex<T>&
     */
    inline Complex<T> &operator--() {
        this->re--;
        return *this;
    }
    /**
     * @brief Multiple increment operator
     *
     * Increments real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(2,1);
     * z++2; // z.re = 4, z.im = 1
     * \endcode
     *
     *
     * @return Complex<T>&
     */
    inline Complex<T> operator++(int) {
        Complex<T> a = *this;
        this->re++;
        return a;
    }
 
    /**
     * @brief Multiple decrement operator
     *
     * Decrement real part of Complex number
     *
     * \code {.cpp}
     * Complex<double> z(2,1);
     * z--2; // z.re = 0, z.im = 1
     * \endcode
     *
     *
     * @return Complex<T>&
     */
    inline Complex<T> operator--(int) {
        Complex<T> a = *this;
        this->re--;
        return a;
    }
 
    std::string str(int prec = 8, char separator = ' ') const {
        std::stringstream ss;
        ss.precision(prec);
        ss << re << separator << im;
        return ss.str();
    }
 
 
    // Convenience method a.conj_mul(b) == a^* b
 
    /**
     * @brief Conjugate multiply method
     * @details Conjugate a (*this) and multiply with give argument b: `a.conj_mul(b)` \f$ \equiv
     * a^* \cdot b\f$
     *
     * @tparam A Type for Complex number b
     * @param b number to multiply with
     * @return Complex<T>
     */
    template <typename A>
    inline Complex<T> conj_mul(const Complex<A> &b) const {
        return Complex<T>(re * b.re + im * b.im, re * b.im - im * b.re);
    }
 
    // Convenience method a.mul_conj(b) == a * b^*
 
    /**
     * @brief Multiply conjugate method
     * @details Multiply a (*this) with conjugate of given argument b: `a.mul_conj(b)` \f$ \equiv a
     * \cdot b^*\f$
     *
     * @tparam A Type for Complex number b
     * @param b number to conjugate and multiply withv
     * @return Complex<T>
     */
    template <typename A>
    inline Complex<T> mul_conj(const Complex<A> &b) const {
        return Complex<T>(re * b.re + im * b.im, im * b.re - re * b.im);
    }
 
    // cast to another number type (IS THIS NEEDED FOR COMPLEX?)
    template <typename Ntype>
    Complex<Ntype> cast_to() const {
        Complex<Ntype> res;
        res.re = re;
        res.im = im;
        return res;
    }
};
 
 
namespace hila {
////////////////////////////////////////////////////////////////////////
// Section for adding complex utility templates (in namespace hila)
// hila::is_complex_or_arithmetic<T>::value
// hila::contains_complex<T>::value
// hila::number_type<T>   returns Complex or arithmetic type
// hila::ntype_op<A,B>        returns the conventionally upgraded complex or scalar number type
// hila::complex_x_scalar_type<A,B>  type of operation Complex<A> * scalar<B>
 
 
////////////////////////////////////////////////////////////////////////
// Define hila::is_complex<T>::value -template, using specialization
template <typename T>
struct is_complex : std::integral_constant<bool, false> {};
 
template <typename T>
struct is_complex<Complex<T>> : std::integral_constant<bool, true> {};
 
/// hila::is_complex_or_arithmetic<T>::value
template <typename T>
struct is_complex_or_arithmetic
    : std::integral_constant<bool, hila::is_arithmetic<T>::value || hila::is_complex<T>::value> {};
 
/////////////////////////////////////////////////////////////////////////
// Utility to check that the type contains complex numbers
// Use as contains_complex<T>::value
 
template <typename T, typename Enable = void>
struct contains_complex : std::integral_constant<bool, false> {};
 
template <typename T>
struct contains_complex<T, typename std::enable_if_t<hila::is_field_class_type<T>::value>>
    : std::integral_constant<bool,
                             hila::contains_type<T, Complex<hila::arithmetic_type<T>>>::value> {};
 
/////////////////////////////////////////////////////////////////////////
// Utility hila::number_type<T>  returns complex or arithmetic type
// depending on the type
 
template <typename T, typename Enable = void, typename N = hila::arithmetic_type<T>>
struct complex_or_arithmetic_type_struct {
    using type = N;
};
 
template <typename T>
struct complex_or_arithmetic_type_struct<
    T, typename std::enable_if_t<hila::contains_complex<T>::value>> {
    using type = Complex<hila::arithmetic_type<T>>;
};
 
template <typename T>
using number_type = typename complex_or_arithmetic_type_struct<T>::type;
 
/////////////////////////////////////////////////////////////////////////
// Utility hila::ntype_op<T1,T2>  returns real or complex type,
// "conventionally" defined double/float etc. upgrading.
// Note:  hila::type_plus<T1,T2> gives e.g. Complex<float>,double -> Complex<float>
 
template <typename T1, typename T2, typename Enable = void>
struct ntype_op_s {
    using type = hila::type_plus<hila::arithmetic_type<T1>, hila::arithmetic_type<T2>>;
};
 
// if one type is complex?
template <typename T1, typename T2>
struct ntype_op_s<T1, T2,
                  typename std::enable_if_t<(hila::contains_complex<T1>::value ||
                                             hila::contains_complex<T2>::value)>> {
    using type = Complex<hila::type_plus<hila::arithmetic_type<T1>, hila::arithmetic_type<T2>>>;
};
 
template <typename T1, typename T2>
using ntype_op = typename ntype_op_s<T1, T2>::type;
 
////////////////////////////////////////////////////////////////////////////
// utility complex_x_scalar, used in Complex<A> + scalar<B> ops
// - if result is convertible to Complex<A>, return Complex<A>
// - otherwise return Complex<type_plus<A,B>>
// This is done in order to keep vector types as vectors
 
template <typename A, typename B, typename Enable = void>
struct complex_x_scalar_s {
    using type = Complex<hila::type_plus<A, B>>;
};
 
template <typename A, typename B>
struct complex_x_scalar_s<
    A, B, typename std::enable_if_t<std::is_assignable<A &, hila::type_plus<A, B>>::value>> {
    using type = Complex<A>;
};
 
template <typename A, typename B>
using complex_x_scalar_type = typename complex_x_scalar_s<A, B>::type;
 
////////////////////////////////////////////////////////////////////////
// as_complex_array(T var)
// casts the var to a pointer to complex<scalar_type<T>>
// assuming var contains complex type.  This enables access
// of complex elements as
//  as_complex_array(var)[i]
// comment out as hilapp gets confused at the moment
////////////////////////////////////////////////////////////////////////
 
// #pragma hila loop_function
// template <typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
// inline const Complex<hila::arithmetic_type<T>> * as_complex_array(const T &var) {
//     return (const Complex<hila::arithmetic_type<T>> *)(void *)&var;
// }
 
// #pragma hila loop_function
// template <typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
// inline Complex<hila::arithmetic_type<T>> * as_complex_array(T &var) {
//     return (Complex<hila::arithmetic_type<T>> *)(void *)&var;
// }
 
////////////////////////////////////////////////////////////////////////
// get_complex_element(var,i)
//    returns the i:th complex number embedded in variable v
// set_complex_element(var,i,value)
//    sets the i:th element in var
////////////////////////////////////////////////////////////////////////
 
template <typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
inline Complex<hila::arithmetic_type<T>> get_complex_in_var(const T &var, int i) {
    return *(reinterpret_cast<const Complex<hila::arithmetic_type<T>> *>(&var) + i);
}
 
template <typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
inline void set_complex_in_var(T &var, int i, const Complex<hila::arithmetic_type<T>> &val) {
    *(reinterpret_cast<Complex<hila::arithmetic_type<T>> *>(&var) + i) = val;
}
 
} // namespace hila
 
// generic Complex constructor - type from arguments
template <typename T, std::enable_if_t<hila::is_floating_point<T>::value, int> = 0>
Complex<T> complex(const T re, const T im) {
    return Complex<T>(re, im);
}
 
 
/**
 * @brief Return real value of Complex number
 * @details Wrapper around Complex::real
 * @tparam T Arithmetic type of a
 * @param a Complex number to get real value from
 * @return T
 */
template <typename T>
inline T real(const Complex<T> &a) {
    return a.re;
}
 
/**
 * @brief Retrun imaginary value of Complex number
 * @details Wrapper around Complex::imag
 * @tparam T Arithmetic type of a
 * @param a Complex number to get imaginary value from
 * @return T
 */
template <typename T>
inline T imag(const Complex<T> &a) {
    return a.im;
}
 
/**
 * @brief Return complex number given by polar representation
 * @details Same as Complex::polar
 * @tparam T Arithmetic type r and arg
 * @param r Radial component of Complex number
 * @param arg Argument of Complex number
 * @return Complex<T>
 */
template <typename T>
Complex<T> polar(T r, T arg) {
    Complex<T> res(r * cos(arg), r * sin(arg));
    return res;
}
 
 
// template <typename T>
// inline Complex<T> operator+(const Complex<T> & a, const Complex<T> & b) {
//   return Complex<T>(a.re + b.re, a.im + b.im);
// }
 
 
#pragma hila loop_function
/**
 * @brief Addition operator Complex + Complex
 * @memberof Complex
 * @details Addition between Complex numbers is defined in the usual way:
 *
 * \f{align}{ z_1, z_2 &\in \mathbf{C} \\ z_1 + z_2 &= \Re(z_1) + \Re(z_2) + [\Im(z_1) + \Im(z_2)]i
 * \f}
 *
 * \code {.cpp}
 * z = z_1 + z_2;
 * \endcode
 *
 * @tparam T1 Type for first complex number
 * @tparam T2 Type for second complex number
 * @tparam Tr Conversion type between T1 and T2
 * @param a First complex number
 * @param b Second complex number
 * @return Complex<Tr>
 */
template <typename T1, typename T2, typename Tr = hila::type_plus<T1, T2>>
inline Complex<Tr> operator+(const Complex<T1> &a, const Complex<T2> &b) {
    return Complex<Tr>(a.re + b.re, a.im + b.im);
}
 
// TODO: for avx vector too -- #define new template macro
/**
 * @brief Addition operator Complex + Scalar
 * @memberof Complex
 * @details Defined in the usual way. \f$z,z_1 \in \mathbb{C}, a \in \mathbb{R}\f$
 * \code {.cpp}
 * z = z_1 + a;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number to sum
 * @param a Scalar to sum
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator+(const Complex<T> &c, const A &a) {
    return hila::complex_x_scalar_type<T, A>(c.re + a, c.im);
}
 
/**
 * @brief Addition operator Scalar + Complex
 * @memberof Complex
 * @details Defined in the usual way.  \f$z,z_1 \in \mathbb{C}, a \in \mathbb{R}\f$
 * \code {.cpp}
 * z = a + z_1;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param a Scalar to sum
 * @param c Complex number to sum
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator+(const A &a, const Complex<T> &c) {
    return hila::complex_x_scalar_type<T, A>(c.re + a, c.im);
}
 
/**
 * @brief Subtraction operator Complex - Complex
 * @memberof Complex
 * @details Subtraction between Complex numbers is defined in the usual way
 * \f{align}{  z_1, z_2 &\in \mathbf{C} \\ z_1 - z_2 &= \Re(z_1) - \Re(z_2) + [\Im(z_1) -
 * \Im(z_2)]i\f}
 *
 * \code {.cpp}
 * z = z_1 - z_2;
 * \endcode
 *
 * @tparam T1 Arithmetic type of a
 * @tparam T2 Arithmetic type of b
 * @tparam Tr Resulting type after subtraction
 * @param a First complex number
 * @param b Second complex number to subtract
 * @return Complex<Tr>
 */
template <typename T1, typename T2, typename Tr = hila::type_plus<T1, T2>>
inline Complex<Tr> operator-(const Complex<T1> &a, const Complex<T2> &b) {
    return Complex<Tr>(a.re - b.re, a.im - b.im);
}
 
/**
 * @brief Subtraction operator Complex - Scalar
 * @memberof Complex
 * @details Defined in the usual way.  \f$z,z_1 \in \mathbb{C}, a \in \mathbb{R}\f$
 * \code {.cpp}
 * z = z_1 - a;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number
 * @param a Scalar to subtract
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator-(const Complex<T> &c, const A &a) {
    return hila::complex_x_scalar_type<T, A>(c.re - a, c.im);
}
 
/**
 * @memberof Complex
 * @brief Subtraction operator Scalar - Complex
 * @details Defined in the usual way.  \f$z,z_1 \in \mathbb{C}, a \in \mathbb{R}\f$
 * \code {.cpp}
 * z = a - z_1;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param a Scalar
 * @param c Complex number to subtract
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator-(const A &a, const Complex<T> &c) {
    return hila::complex_x_scalar_type<T, A>(a - c.re, -c.im);
}
 
/**
 * @brief Multiplication operator Complex * Complex
 * @memberof Complex
 * @details Defined in the usual way
 *
 * \f{align}{z, z_1 &= x + iy, z_2 = x' + iy' \in \mathbb{C} \\
 * z_1 z_2 &= (x + iy)(x' + iy') = (xx'-yy') + i(xy' + yx')\f}
 * \code {.cpp}
 * z = z_1 * z_2;
 * \endcode
 * @tparam T1 Arithmetic type of a
 * @tparam T2 Arithmetic type of b
 * @tparam Tr Resulting type after multiplication
 * @param a
 * @param b
 * @return Complex<Tr>
 */
template <typename T1, typename T2, typename Tr = hila::type_mul<T1, T2>>
inline Complex<Tr> operator*(const Complex<T1> &a, const Complex<T2> &b) {
    return Complex<Tr>(a.re * b.re - a.im * b.im, a.re * b.im + a.im * b.re);
}
 
/**
 * @brief Multiplication operator Complex * Scalar
 * @memberof Complex
 * @details Multiplication between Complex and scalar is defined in the usual way
 * \f{align}{z,z_1 &= x + iy \in \mathbb{C}, a \in \mathbb{R} \\
 * z_1 * a &= (x\cdot a + iy\cdot a)\f}
 * \code {.cpp}
 * z = z_1 * a;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number to multiply
 * @param a Scalar to multiply
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator*(const Complex<T> &c, const A &a) {
    return hila::complex_x_scalar_type<T, A>(c.re * a, c.im * a);
}
 
/**
 * @brief Multiplication operator Scalar * Complex
 * @memberof Complex
 * @details Multiplication between Complex and scalar is defined in the usual way
 * \f{align}{z,z_1 &= x + iy \in \mathbb{C}, a \in \mathbb{R} \\
 * z * a &= (x\cdot a + iy\cdot a)\f}
 * \code {.cpp}
 * z = a * z_1;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number to multiply
 * @param a Scalar to multiply
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator*(const A &a, const Complex<T> &c) {
    return hila::complex_x_scalar_type<T, A>(a * c.re, a * c.im);
}
 
// /   a/b = ab*/| b |^2
// template <typename T>
// inline Complex<T> operator/(const Complex<T> & a, const Complex<T> & b) {
//   T n = b.squarenorm();
//   return Complex<T>( (a.re*b.re + a.im*b.im)/n, (a.im*b.re - a.re*b.im)/n );
// }
 
/**
 * @brief Division operator Complex / Complex
 * @memberof Complex
 * @details Defined in the usual way
 * \f{align}{ z,z_1,z_2 &\in \mathbb{C} \\
 * \frac{z_1}{z_2} &= \frac{z_1\cdot z_2^{*}}{|z_2|^2} \f}
 * \code {.cpp}
 * z =z_1 / z_2;
 * \endcode
 * @tparam T1 Arithmetic type of a
 * @tparam T2 Arithmetic type of b
 * @tparam Tr Resulting type after division
 * @param a Complex number to divide
 * @param b Complex number to divide with
 * @return Complex<Tr>
 */
template <typename T1, typename T2, typename Tr = hila::type_mul<T1, T2>>
inline Complex<Tr> operator/(const Complex<T1> &a, const Complex<T2> &b) {
    T2 n = 1.0 / b.squarenorm();
    return Complex<Tr>((a.re * b.re + a.im * b.im) * n, (a.im * b.re - a.re * b.im) * n);
}
 
/**
 * @memberof Complex
 * @brief Division operator Complex / Scalar
 * @details Defined in the usual way
 * \f{align}{z, z_1=x + iy &\in \mathbb{C}, a \in \mathbb{R} \\
 * \frac{z_1}{a} &= \frac{x}{a} + i\cdot \frac{y}{a} \f}
 * \code {.cpp}
 * z = z_1 / a;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number to divide
 * @param a Scalar to divide with
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator/(const Complex<T> &c, const A &a) {
    return hila::complex_x_scalar_type<T, A>(c.re / a, c.im / a);
}
 
// a/c = ac*/|c|^2
/**
 * @memberof Complex
 * @brief Division operator Scalar / Complex
 * @details Defined in the usual way
 * \f{align}{ z,z_1=x + iy &\in \mathbb{C}, a \in \mathbb{R} \\
 * \frac{a}{z_1} &= \frac{az^*}{|z|^2} \f}
 * \code {.cpp}
 * z = a / z_1;
 * \endcode
 * @tparam T Arithmetic type of c
 * @tparam A Arithmetic type of a
 * @param c Complex number to divide
 * @param a Scalar to divide with
 * @return auto
 */
template <typename T, typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline auto operator/(const A &a, const Complex<T> &c) {
    T n = c.squarenorm();
    return hila::complex_x_scalar_type<T, A>((a * c.re) / n, -(a * c.im) / n);
}
 
/**
 * @brief Multiply add with Complex numbers
 * @memberof Complex
 * @details Defined as
 *
 * \code{.cpp}
 * mul_add(a,b,c) = a*b + c;
 * \endcode
 * @tparam T Arithmetic type of a,b and c
 * @param a Complex number to multiply
 * @param b Complex number to multiply
 * @param c Complex number to add to result of multiplication
 * @return Complex<T>
 */
template <typename T>
inline Complex<T> mul_add(const Complex<T> &a, const Complex<T> &b, const Complex<T> &c) {
    // a*b + c
    Complex<T> r;
    T t1 = mul_add(a.re, b.re, c.re);
    T t2 = mul_add(a.re, b.im, c.im);
    r.re = mul_add(a.im, b.im, t1); // -a.im*b.im + a.re*b.re + c.re
    r.im = mul_add(a.im, b.re, t2); // a.im*b.re + a.re*b.im + c.im
    return r;
}
 
/**
 * @brief Compare equality of two complex numbers
 * @memberof Complex
 * Two numbers are equal, if the real and imaginary components are respectively equal
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param a Complex number to compare
 * @param b Complex number to compare
 * @return true if values compare to equal
 */
 
template <typename A, typename B>
inline bool operator==(const Complex<A> &a, const Complex<B> &b) {
    return (a.re == b.re && a.im == b.im);
}
 
/**
 * @memberof Complex
 * @brief Compare equality of Complex and scalar
 *
 * Two numbers are equal, if the arithmetic values are equal: thus,
 * complex and real comparison  (a + i b) == a
 * is true if b == 0.
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param a Complex number to compare
 * @param b Scalar to compare
 * @return true if values compare to equal
 */
template <typename A, typename B, std::enable_if_t<hila::is_arithmetic<B>::value, int> = 0>
inline bool operator==(const Complex<A> &a, const B b) {
    return (a.re == b && a.im == 0);
}
 
/**
 * @memberof Complex
 * @brief Compare equality of Scalar and Complex
 *
 * Two numbers are equal, if the arithmetic values are equal: thus,
 * complex and real comparison  (a + i b) == a
 * is true if b == 0.
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param b Complex number to compare
 * @param a Scalar to compare
 * @return true if values compare to equal
 */
template <typename A, typename B, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline bool operator==(const A a, const Complex<B> &b) {
    return b == a;
}
 
/**
 * @brief Compare non-equality of two complex numbers
 * @memberof Complex
 * @details Negation of operator==()
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param a Complex number to compare
 * @param b Complex number to compare
 * @return true if values are not arithmetically equal
 */
template <typename A, typename B>
inline bool operator!=(const Complex<A> &a, const Complex<B> &b) {
    return (a.re != b.re || a.im != b.im);
}
 
/**
 * @brief Compare non-equality of Complex number and Scalar
 * @memberof Complex
 * @details Negation of operator==()
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param a Complex number to compare
 * @param b Scalar to compare
 * @return true if values are not arithmetically equal
 */
template <typename A, typename B, std::enable_if_t<hila::is_arithmetic<B>::value, int> = 0>
inline bool operator!=(const Complex<A> &a, const B b) {
    return (a.re != b || a.im != 0);
}
 
/**
 * @brief Compare non-equality of Scalar and Complex number
 * @memberof Complex
 * @details Negation of operator==()
 *
 * @tparam A Arithmetic type of a
 * @tparam B Arithmetic type of b
 * @param a Scalar to compare
 * @param b Complex number to compare
 * @return true if values are not arithmetically equal
 */
template <typename A, typename B, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
inline bool operator!=(const A a, const Complex<B> &b) {
    return b != a;
}
 
 
// Cast operators to different number or Complex type
// cast_to<double>(a);
// cast_to<float>(b);
// Cast from number->number, number->Complex, Complex->Complex OK,
//     Complex->number not.
 
template <typename Ntype, typename T, std::enable_if_t<hila::is_arithmetic<Ntype>::value, int> = 0>
Complex<Ntype> cast_to(const Complex<T> &m) {
    Complex<Ntype> res;
    res = m;
    return res;
}
 
//////////////////////////////////////////////////////////////////////////////////
// Some operations in function form.  Useful in templates when the arg type is not known
 
/**
 * @brief Return absolute value of Complex number
 * @details Wrapper around Complex::abs
 * @tparam T Arithmetic type of a
 * @param a Complex number to get abs from
 * @return T
 */
template <typename T>
inline T abs(const Complex<T> &a) {
    return a.abs();
}
 
/**
 * @brief Return argument of Complex number
 * @details Wrapper around Complex::arg
 * @tparam T Arithmetic type of a
 * @param a Complex number to get arg from
 * @return T
 */
template <typename T>
inline T arg(const Complex<T> &a) {
    return a.arg();
}
 
/**
 * @brief Return conjugate of Complex number
 * @details Wrapper around Complex::conj
 * @tparam T Arithmetic type of a
 * @param a Complex number to get conjugate from
 * @return Complex<T>
 */
template <typename T>
inline Complex<T> conj(const Complex<T> &val) {
    return val.conj();
}
 
/**
 * @brief Return dagger of Complex number
 * @details Wrapper around Complex::conj
 * @tparam T Arithmetic type of a
 * @param a Complex number to get conjugate from
 * @return Complex<T>
 */
template <typename T>
inline Complex<T> dagger(const Complex<T> &val) {
    return val.conj();
}
 
/**
 * @brief Return Squarenorm of Complex number
 * @details Wrapper around Complex::squarenorm
 * @tparam T Arithmetic type of a
 * @param a Complex number to compute squarenorm of
 * @return T
 */
template <typename T>
inline auto squarenorm(const Complex<T> &val) {
    return val.squarenorm();
}
 
 
//////////////////////////////////////////////////////////////////////////////////
/// Print a complex value as (re,im)
//////////////////////////////////////////////////////////////////////////////////
 
/**
 * @brief Stream operator
 * @details Print Complex number as "A.re A.im"
 * @tparam T Arithmetic type of A
 * @param strm
 * @param A Complex number to print
 * @return std::ostream&
 */
template <typename T>
std::ostream &operator<<(std::ostream &strm, const Complex<T> &A) {
    return strm << A.real() << ' ' << A.imag();
}
 
/// //////////////////////////////////////////////////////////////////////////////
/// Function hila::to_string
 
namespace hila {
/**
 * @brief Return Complex number as std::string
 *
 * @tparam T Arithmetic type of A
 * @param A Complex number to convert
 * @param prec Precision to represent Complex number at
 * @param separator Separator for Complex number
 * @return std::string
 */
template <typename T>
std::string to_string(const Complex<T> &A, int prec = 8, char separator = ' ') {
    return A.str(prec, separator);
}
 
/**
 * @brief Return well formatted Complex number as std::string
 * @details Output is as "(A.re, A.im)"
 *
 * @tparam T Arithmetic type of A
 * @param A Complex number to print
 * @param prec Precision to print Complex number as
 * @return std::string
 */
template <typename T>
std::string prettyprint(const Complex<T> &A, int prec = 8) {
    std::stringstream ss;
    ss.precision(prec);
    ss << "( " << A.real() << ", " << A.imag() << " )";
    return ss.str();
}
 
} // namespace hila
 
 
/**
 * @brief Imaginary type, used to represent purely imaginary numbers
 *
 * Useful for reducing multiply operations in im * complex or im * real -ops
 * Derived from Complex class, so generic complex ops should remain valid
 * Defines only operators * and /, others go via Complex class
 *
 * Note: Imaginary_t should be used in Field variables
 *
 * @tparam T  type of imaginary (float/double)
 */
template <typename T>
class Imaginary_t : public Complex<T> {
  public:
    constexpr Imaginary_t() = default;
    ~Imaginary_t() = default;
    constexpr Imaginary_t(const Imaginary_t &i) = default;
 
    // construct from scalar
#pragma hila loop_function
    template <typename A, std::enable_if_t<hila::is_arithmetic<A>::value, int> = 0>
    explicit constexpr Imaginary_t(const A v) : Complex<T>(0, v) {}
 
    constexpr Imaginary_t operator-() const {
        return Imaginary_t<T>(-this->im);
    }
 
    constexpr Imaginary_t operator+() const {
        return *this;
    }
};
 
///////////////////////////////////////////////////////////////////////////////////////
/// @brief Imaginary unit I - global variable
///
/// Don't use #define'd I : this will conflict with some headers in rocm
///
/// For some reason it is sufficient to use only __device__
#if defined(CUDA) || defined(HIP)
__device__
#endif
    constexpr Imaginary_t<double>
        I(1.0);
 
// constexpr Complex<double> I(0,1);
// #define I Imaginary_t<double>(1.0)
 
///////////////////////////////////////////////////////////////////////////////////////
 
// Imaginary * object containing complex
template <typename A, typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
inline auto operator*(const Imaginary_t<A> &i, const T &c) {
    Complex<hila::arithmetic_type<T>> ca, cb;
    T res;
    constexpr int n_cmplx = sizeof(T) / sizeof(Complex<hila::arithmetic_type<T>>);
    for (int k = 0; k < n_cmplx; k++) {
        ca = hila::get_complex_in_var(c, k);
        cb.re = -ca.im * i.imag();
        cb.im = ca.re * i.imag();
        hila::set_complex_in_var(res, k, cb);
    }
    return res;
}
 
// object containing complex * imaginary
template <typename A, typename T, std::enable_if_t<hila::contains_complex<T>::value, int> = 0>
inline auto operator*(const T &c, const Imaginary_t<A> &i) {
    return i * c;
}
 
 
// Imag * scalar, returns imag
// note: using std::is_arithmetic, not done for vector types
template <typename A, typename T, std::enable_if_t<std::is_arithmetic<T>::value, int> = 0>
inline Imaginary_t<A> operator*(Imaginary_t<A> i, const T &c) {
    i.imag() *= c;
    return i;
}
 
// scalar * imag, returns imag
template <typename A, typename T, std::enable_if_t<std::is_arithmetic<T>::value, int> = 0>
inline Imaginary_t<A> operator*(const T &c, Imaginary_t<A> i) {
    i.imag() *= c;
    return i;
}
 
// Imaginary * Imaginary, returns scalar
template <typename A, typename B>
inline auto operator*(const Imaginary_t<A> &a, const Imaginary_t<B> &b) {
    return -(a.imag() * b.imag());
}
 
////////////////////////////
 
 
// @brief Imaginary / real value, returning imaginary
// Note: for vectorized types the generic version is used
template <typename T, typename A, std::enable_if_t<std::is_arithmetic<A>::value, int> = 0>
inline auto operator/(Imaginary_t<T> i, const A &a) {
    i.imag() /= a;
    return i;
}
 
// @brief Imaginary / Imaginary, returning real
template <typename A, typename B>
inline auto operator/(const Imaginary_t<A> &a, const Imaginary_t<B> &b) {
    return a.imag() / b.imag();
}
 
 
///////////////////////////////////////////////////////////////////////////////
// Set of complex functions
///////////////////////////////////////////////////////////////////////////////
/**
 * @name Mathematical functions
 * @return Complex T
 * @memberof Complex
 *
 * @{
 */
/// \f$\exp(z)\f$
template <typename T>
inline Complex<T> exp(const Complex<T> z) {
    return exp(z.re) * Complex<T>(cos(z.im), sin(z.im));
}
 
/// \f$\exp(i\cdot x)\f$
template <typename T, std::enable_if_t<hila::is_arithmetic<T>::value, int> = 0>
inline Complex<T> expi(T a) {
    return Complex<T>(cos(a), sin(a));
}
 
/// \f$\exp(\Im(z))\f$
template <typename T>
inline Complex<T> exp(const Imaginary_t<T> im) {
    return expi(im.imag());
}
 
/// \f$\log{z}\f$
template <typename T>
inline Complex<T> log(Complex<T> z) {
    return Complex<T>(static_cast<T>(0.5) * log(z.squarenorm()), z.arg());
}
 
// sqrt(z) branch cut at -x axis
 
/// \f$\sqrt{z}\f$
template <typename T>
inline Complex<T> sqrt(Complex<T> z) {
    T r = z.squarenorm();
    T a = z.arg();
    return pow(r, 0.25) * expi(0.5 * a);
}
 
/// \f$\sqrt[3]{z}\f$
template <typename T>
inline Complex<T> cbrt(Complex<T> z) {
    T r = z.squarenorm();
    T a = z.arg();
    return pow(r, (1.0 / 6.0)) * expi((1.0 / 3.0) * a);
}
 
/// pow(z.p) = \f$z^p\f$ = \f$exp(p*log(z))\f$
template <typename A, typename B>
inline auto pow(Complex<A> z, Complex<B> p) {
    return exp(p * log(z));
}
 
/// pow(z.p) with scalar power
template <typename T, typename S, std::enable_if_t<hila::is_arithmetic<S>::value, int> = 0>
inline Complex<T> pow(Complex<T> z, S p) {
    return exp(p * log(z));
}
 
/// pow(z.p) with scalar base
template <typename T, typename S, std::enable_if_t<hila::is_arithmetic<S>::value, int> = 0>
inline Complex<T> pow(S z, Complex<T> p) {
    return exp(p * log(z));
}
 
/// \f{align}{sin(z) &= \sin(\Re(z) + i \Im(z)) \\
/// &= \sin(\Re(z))\cos(i \Im(z)) + \cos(\Re(z))\sin(i \Im(z)) \\
/// &= \sin(\Re(z)) \cosh(\Im(z)) + i \cos(\Re(z)) \sinh(\Im(z)) \f}
template <typename T>
inline Complex<T> sin(Complex<T> z) {
    return Complex<T>(sin(z.re) * cosh(z.im), cos(z.re) * sinh(z.im));
}
 
/// \f{align}{\cos(z) &= \cos(\Re{z})\cos(i \Im(z)) - \sin(\Re{z})\sin(i \Im{z}) \\
/// &= \cos(\Re{z})\cosh(\Im(z)) - i \sin(\Re{z})\sinh(\Im(z))\f}
template <typename T>
inline Complex<T> cos(Complex<T> z) {
    return Complex<T>(cos(z.re) * cosh(z.im), -sin(z.re) * sinh(z.im));
}
 
/// \f$\tan(z) = \frac{\sin(z)}{\cos(z)}\f$ - rely on optimizer to simplify
template <typename T>
inline Complex<T> tan(Complex<T> z) {
    return sin(z) / cos(z);
}
 
/// sinh(z) = sinh(re)cosh(i im) + cosh(re)sinh(i im)
/// = sinh(re)cos(im) + i cosh(re)sin(im)
template <typename T>
inline Complex<T> sinh(Complex<T> z) {
    return Complex<T>(sinh(z.re) * cos(z.im), cosh(z.re) * sin(z.im));
}
 
/// cosh(z) = cosh(re)cosh(i im) - sinh(re)sinh(i im)
/// = cosh(re)cos(im) - i sinh(re)sin(im)
template <typename T>
inline Complex<T> cosh(Complex<T> z) {
    return Complex<T>(cosh(z.re) * cos(z.im), sinh(z.re) * sin(z.im));
}
 
/// \f$\tanh(z)\f$
template <typename T>
inline Complex<T> tanh(Complex<T> z) {
    return sinh(z) / cosh(z);
}
 
/// \f$\arctan(z)\f$
template <typename T>
inline Complex<T> atan(Complex<T> z) {
    return -0.5 * I * (log((I - z) / (I + z)));
}
 
/// \f$\arcsin(z)\f$
template <typename T>
inline Complex<T> asin(Complex<T> z) {
    return -I * (log(I * z + sqrt(1 - z * z)));
}
 
/// \f$\arccos(z)\f$
template <typename T>
inline Complex<T> acos(Complex<T> z) {
    return -I * (log(z + I * (sqrt(1 - z * z))));
}
 
/// \f$\text{artanh}(z)\f$
template <typename T>
inline Complex<T> atanh(Complex<T> z) {
    return 0.5 * log((1 + z) / (1 - z));
}
 
/// \f$\text{arsinh}(z)\f$
template <typename T>
inline Complex<T> asinh(Complex<T> z) {
    return log(z + sqrt(1 + z * z));
}
 
/// \f$\text{arcosh}(z)\f$
template <typename T>
inline Complex<T> acosh(Complex<T> z) {
    return log(z + sqrt(z * z - 1));
}
 
/** @} */
 
 
//////////////////////////////////////////////////////////////////////////////////
/// Operators to implement imaginary unit 1_i, enablig expressions  3 + 2_i  etc.
/// This is defined as an user-defined literal, which requires an underscore.
////////////////////////////////////////////////////////////////////////////////
 
constexpr Imaginary_t<double> operator""_i(long double a) {
    return Imaginary_t<double>{a};
}
 
constexpr Imaginary_t<double> operator""_i(unsigned long long a) {
    return Imaginary_t<double>(a);
}
 
 
#endif