#include "kernels.h"#include "math.h"/* * If one wants to add a new kernel, make a new function with  * the name of this kernel. Make a declaration of this function * in the header file ./c-src/kernels.h, and link the new function * to the name of the kernel in the function 'createKernel(...)'  *  * The source code has to be recompiled (look for details in the manual). */ /********************************************************** *********************** kernel implementations *********** **********************************************************//* computation of the standard 2-norm */double norm(int dim, const double* x1, const double* x2){  int t;  double norm,h;  norm =0.0;  for(t=0; t<dim; t++)  {    h = x1[t] - x2[t];    norm = norm + h*h;  }  //printf("norm |[%f %f] - [%f %f]| = %f; ",x1[0],x1[1], x2[0],x2[1], norm);  return norm;}/* computation of the standard 2-norm */double dotProduct(int dim, const double* x1, const double* x2){  int t;  double norm;  norm =0.0;  for(t=0; t<dim; t++)    norm = norm + x1[t]*x2[t];  return norm;}/* possible kernel functions *//* RBF kernel....  * the parameter is sigma^2 */double kernel_fct_RBF(void* kp, int i, int j){  double norm_x;  kernel* k;  k = (kernel*) kp;  norm_x = norm(k->_dim_x, GETDP(k,i), GETDP(k,j));  //printf("RBF(%d,%d,%f) = %f; ",i,j,k->_pars[0],exp((- (double) 1/ ((k->_pars[0])) )*norm_x));  return exp((- (double) 1/ ((k->_pars[0])) )*norm_x);}/*  lineaire kernel, based on the standard dot-product * there's no parameter involved */double kernel_fct_lineair(void* kp, int i, int j){  double dp;  kernel* k;  k = (kernel*) kp;  dp = dotProduct(k->_dim_x, GETDP(k,i), GETDP(k,j));  return dp; }/* multi-layer perceptron kernel */double kernel_fct_poly(void* kp, int i, int j){  kernel* k;  double dp;  k = (kernel*) kp;  dp = dotProduct(k->_dim_x, GETDP(k,i), GETDP(k,j));  return pow(dp+(k->_pars[0]),k->_pars[1]);}/* multi-layer perceptron kernel */double kernel_fct_mlp(void* kp, int i, int j){  kernel* k;  double dp;  k = (kernel*) kp;  dp = dotProduct(k->_dim_x, GETDP(k,i), GETDP(k,j));  return tanh(k->_pars[0]*dp-k->_pars[1]);}/* spline kernel */double kernel_fct_spline(void* kp, int i, int j){  kernel* k;  double dp;  k = (kernel*) kp;  dp = dotProduct(k->_dim_x, GETDP(k,i), GETDP(k,j));  if (dp<=1) return (2/3)-dp*dp + 0.5*dp*dp*dp;  else if (dp<=2) return (2-dp)*(2-dp)*(2-dp)/6;  else return 0;  return 0;}/**************************************************************** ******** structure containing info for calculation kernel ****** ****************************************************************//*  * constructor: *   x_dim*nb = length(svX) and y-dim*nb(svY) *   it`s not computed because of the overhead... * */kernel* createKernel(const char* kernel_type, 		     const double* pars){  kernel* k_ptr;  k_ptr = (kernel*)MALLOC(sizeof(kernel));  k_ptr->_pars = pars;  /*   * add here link to new kernel if appropriate   */   if (!strcmp(kernel_type,"RBF_kernel"))     k_ptr->kernel_fct = &kernel_fct_RBF;  else if (!strcmp(kernel_type,"lin_kernel"))    k_ptr->kernel_fct = &kernel_fct_lineair;   else if (!strcmp(kernel_type,"MLP_kernel"))      k_ptr->kernel_fct = &kernel_fct_mlp;   else if (!strcmp(kernel_type,"spline_kernel"))    k_ptr->kernel_fct = &kernel_fct_spline;  else if (!strcmp(kernel_type,"poly_kernel"))    k_ptr->kernel_fct = &kernel_fct_poly;  else {    printf("unknown kernel for C-progam; for possible kernels, look in c-src/kernels.h\n");    exit(1);  }  return k_ptr;}/*  * add the parameters for retrieving a datapoint (timeserie, dynamic)  */void setDPR(kernel* k_ptr, const double* DPR(int, void*), void* options, int xdim, int ydim, int nb){  k_ptr->_DPR = DPR;  k_ptr->_DPRoptions = options;  k_ptr->_dim_x = xdim;  k_ptr->_dim_y = ydim;  k_ptr->_nb = nb;}/*  * get value of kernel matrix of position (i,j) */double computeKernelIJ(kernel* k_ptr, int i, int j){  double ff;  ff =  k_ptr->kernel_fct(k_ptr, i,j);  //printf("kernel value [%d,%d] = (%f,%f) = %f; \n",i,j,GETDP(k_ptr,i)[0],GETDP(k_ptr,j)[0], ff);  return ff;}/*  * destruct the used memory  */void destructKernel(kernel* k_ptr){  FREE(k_ptr);  return;}