# ifndef H_NEURAL_NET_PDE_H
# define H_NEURAL_NET_PDE_H

struct Neural_Net_PDE 
{
  double (*PDE)( double x, double y, double u, double u_x, double u_y,
    double u_xx, double u_xy, double u_yy );
  void (*phi_func)( struct Neural_Net_PDE *nn, double x, double y );
  double bb_xrange[2];
  double bb_yrange[2];
  int q; // number of units in the hidden layer
  int nu; // the number of training points
  double **training_points; // the array of training points
  double (*exact_sol)(double x, double y); // NULL if no exact solution available
  char *geomview_out;
  char *maple_out;
  char *matlab_out;
  int grid[2];
//
// no user modifiable parts beyond this point!
//
  int nweights; // 4*q
  double *weights; // the array of u, v, w
  double sigma[3]; // array to hold sigma, sigma', sigma''
  double phi[3][3]; // array to hold phi and derivatives.
  double N[3][3];
};

void Neural_Net_end ( struct Neural_Net_PDE *nn );
double Neural_Net_error_vs_exact ( struct Neural_Net_PDE *nn, int m, int n );
void Neural_Net_eval ( struct Neural_Net_PDE *nn, double x, double y );
void Neural_Net_init ( struct Neural_Net_PDE *nn );
void Neural_Net_plot_with_maple ( struct Neural_Net_PDE *nn, int n, int m, 
  char *outfile );
void Neural_Net_plot_with_matlab ( struct Neural_Net_PDE *nn, int n, int m,
  char *header );
double Neural_Net_residual ( double *weights, int nweights, void *params );
double residual_at_x_y ( struct Neural_Net_PDE *nn, double x, double y );
void show_usage ( char *progname );
void sigmoid ( double x, double *sigma );
void timestamp ( );

#endif