cosmotool/python/_cosmo_bispectrum.cpp

#include <iostream>
#include <boost/format.hpp>
#include <boost/multi_array.hpp>
#include <sys/types.h>
#include <cmath>

using std::cout;
using std::endl;
using boost::format;


#if defined _WIN32 || defined __CYGWIN__
  #ifdef BUILDING_DLL
    #ifdef __GNUC__
      #define DLL_PUBLIC __attribute__ ((dllexport))
    #else
      #define DLL_PUBLIC __declspec(dllexport) // Note: actually gcc seems to also supports this syntax.
    #endif
  #else
    #ifdef __GNUC__
      #define DLL_PUBLIC __attribute__ ((dllimport))
    #else
      #define DLL_PUBLIC __declspec(dllimport) // Note: actually gcc seems to also supports this syntax.
    #endif
  #endif
  #define DLL_LOCAL
#else
  #if __GNUC__ >= 4
    #define DLL_PUBLIC __attribute__ ((visibility ("default")))
    #define DLL_LOCAL  __attribute__ ((visibility ("hidden")))
  #else
    #define DLL_PUBLIC
    #define DLL_LOCAL
  #endif
#endif



struct ModeSet
{
    size_t N1, N2, N3;
    
    struct TriangleIterator
    {
        ssize_t i1, i2, i3;
        size_t N1, N2, N3;
        
        
        TriangleIterator& operator++() {
            i3++;
            if (i3==N3) { i3 = 0; i2++; }
            if (i2==N2) { i2 = 0; i1++; }
            return *this;
        }
    
        bool operator!=(const TriangleIterator& t) const {
            return i1!=t.i1 || i2!=t.i2 || i3 != t.i3;
        }
        
        bool in_box() const {
            ssize_t hN1 = N1/2, hN2 = N2/2, hN3 = N3/2;
            
            return (i1 >= -hN1) && (i1 < hN1) && (i2 >= -hN2) && (i2 < hN2) && (i3 >= -hN3) && (i3 < hN3);
        }
        
        TriangleIterator operator+(const TriangleIterator& other_t) const {
            TriangleIterator t = *this;
            
            t.i1 = (t.i1+other_t.i1);
            t.i2 = (t.i2+other_t.i2);
            t.i3 = (t.i3+other_t.i3);
            return t;
        }
    
        TriangleIterator real() const {
            TriangleIterator t = *this;
            if (t.i1 >= N1/2)
                t.i1 -= N1;  
            if (t.i2 >= N2/2)
                t.i2 -= N2;  
            return t;
        }
        
        double norm() const {
            double r1 = i1, r2 = i3, r3 = i3;
            return std::sqrt(r1*r1 + r2*r2 + r3*r3);
        }
  
        TriangleIterator& operator*() { return *this; }
    };

    ModeSet(size_t N1_, size_t N2_, size_t N3_)
        : N1(N1_), N2(N2_), N3(N3_) {} 
    TriangleIterator begin() const {
        TriangleIterator t;
        t.i1 = t.i2 = t.i3 = 0;
        t.N1 = N1;
        t.N2 = N2;
        t.N3 = N3;
        return t;
    }

    TriangleIterator end() const {
        TriangleIterator t;
        t.i2 = t.i3 = 0;
        t.i1 = N1;
        t.N1 = N1;
        t.N2 = N2;
        t.N3 = N3;
        return t;
    }

};

extern "C" DLL_PUBLIC
void CosmoTool_compute_bispectrum(
    double *delta_hat, size_t Nx, size_t Ny, size_t Nz,
    size_t *Ntriangles,
    double* B, double delta_k, size_t Nk ) 
{
    // First remap to multi_array for easy access
    size_t kNz = Nz/2+1;
    boost::multi_array_ref<std::complex<double>, 3> a_delta(reinterpret_cast<std::complex<double>*>(delta_hat), boost::extents[Nx][Ny][kNz]); 
    boost::multi_array_ref<size_t, 3> a_Nt(Ntriangles, boost::extents[Nk][Nk][Nk]); 
    boost::multi_array_ref<std::complex<double>, 3> a_B(reinterpret_cast<std::complex<double>*>(B), boost::extents[Nk][Nk][Nk]); 
    typedef std::complex<double> CType;

    // First loop over m1
    for (auto m1 : ModeSet(Nx, Ny, kNz)) {
        CType& v1 = a_delta[m1.i1][m1.i2][m1.i3];
        // Second mode m2
        for (auto m2 : ModeSet(Nx, Ny, kNz)) {
            // Now derive m3
            CType& v2 = a_delta[m2.i1][m2.i2][m2.i3];
            auto m3 = (m1.real()+m2.real());
 
            if (!m3.in_box())
                continue;

            size_t q1 = std::floor(m1.norm()/delta_k);
            size_t q2 = std::floor(m2.norm()/delta_k);
            size_t q3 = std::floor(m3.norm()/delta_k);


            if (q1 > Nk || q2 > Nk || q3 > Nk)
                continue;

            CType prod = v1*v2;
            // We use hermitic symmetry to get -m3, it is just the mode in m3 but conjugated.
            if (m3.i3 > 0) {
                if (m3.i1 < 0) m3.i1 += m3.N1; 
                if (m3.i2 < 0) m3.i2 += m3.N2;
                prod *= std::conj(a_delta[m3.i1][m3.i2][m3.i3]);
            } else {
                m3.i1 = -m3.i1;
                m3.i2 = -m3.i2;
                if (m3.i1 < 0) m3.i1 += m3.N1; 
                if (m3.i2 < 0) m3.i2 += m3.N2; 
                prod *= a_delta[m3.i1][m3.i2][m3.i3];
            }           
            
//            a_Nt[q1][q2][q3] ++;
//            a_B[q1][q2][q3] += prod;
        }
    }
}


extern "C" DLL_PUBLIC
void CosmoTool_compute_powerspectrum(
    double *delta_hat, size_t Nx, size_t Ny, size_t Nz,
    size_t *Ncounts,
    double* P, double delta_k, size_t Nk ) 
{
    // First remap to multi_array for easy access
    size_t kNz = Nz/2+1;
    boost::multi_array_ref<std::complex<double>, 3> a_delta(reinterpret_cast<std::complex<double>*>(delta_hat), boost::extents[Nx][Ny][kNz]); 
    boost::multi_array_ref<size_t, 1> a_Nc(Ncounts, boost::extents[Nk]); 
    boost::multi_array_ref<double, 1> a_P(reinterpret_cast<double*>(P), boost::extents[Nk]); 
    typedef std::complex<double> CType;

    // First loop over m1
    for (auto m1 : ModeSet(Nx, Ny, kNz)) {
        CType& v1 = a_delta[m1.i1][m1.i2][m1.i3];

        size_t q1 = std::floor(m1.norm()/delta_k);

        if (q1 > Nk)
            continue;

        a_Nc[q1] ++;
        a_P[q1] += std::norm(v1);
    }
}