extern "C" {
#include <math.h>
    
#define PI 3.14159265358979323846
#define PI_2 1.57079632679489661923
    
    __global__ void
    spinFact(long* param, float* w)
    {
        unsigned long i = blockIdx.x*blockDim.x+threadIdx.x; // (unsigned long)s->get_param(0);
    
        long n = param[0];

        float angle[2];
        angle[0] = (float)(2*i*PI/(float)n);
        angle[1] = (float)((2*i*PI/(float)n) + PI_2);

        w[2*i] = cos(angle[0]);
        w[2*i+1] = cos(angle[1]);
    }
}