#ifndef interaction_h
#define interaction_h

#include <Python.h>
#include <numpy/ndarraytypes.h>
#include <numpy/ufuncobject.h>

/*
 * This is a quite generic force function mapping a 
 * distance to the magnitude of a force. The coefficients 
 * are an array of length 19 and the force function 
 * is given as:
 *
 * (c0 + c1*r + c2*r^2 + ... + c6*r^6) * c7 * exp(c8*(r - c9))
 * + c10 * exp(c11 * (r - c12)) 
 * + c13 * exp(c14 * (r - c15)^2)
 * + c16 * exp(c17 * (r - c18)^2)
 * */
static float 
interaction_force_function
	( float r
	, float * coefficients);

static void
interaction_ufunc_float2D
	( char ** args
	, npy_intp * dimensions
	, npy_intp * steps
	, void * data);


#endif