#define PI       3.14159265358979323846
#define ERREXIT  1
#define ERRNAN   101
#define ERRNPD   102
#define ERRSING  104
#define ERRSOB   110
#define ERRNCM   111

#ifndef ABS
#define ABS(a)     (((a) < 0) ? -(a) : (a))
#endif
#ifndef MIN
#define MIN(a, b)  ((a) < (b) ? (a) : (b))
#endif
#ifndef MAX
#define MAX(a, b)  ((a) > (b) ? (a) : (b))
#endif


double beta(double alpha, double beta);
double besselK(double x, double alpha, bool scale = false);
void   besselK(double *x, double *alpha, long *nb, bool *ize, double *bk,
               long *ncalc);
double dnorm(double x, double mean = 0.0, double sd = 1.0);
void   error(char foo[], char message[], int errno);
int    finit(char *infile, char *name, unsigned short int *target, int n);
int    finit(char *infile, char *name, int *target, int n);
int    finit(char *infile, char *name, double *target, int n);
double haversine(double lat1, double lon1, double lat2, double lon2);
double lgamma(double alpha);
double matern(double x, int n, double theta);
double pnorm(double x, double mean = 0.0, double sd = 1.0);
double rbeta(double alpha, double beta);
double rgamma(double alpha, double beta = 1.0);
double rnorm(double mean = 0.0, double sd = 1.0);
double rtnorm(double mean, double sd, double a, double b,
              bool ainf = false, bool binf = false);
double trunc(double x);

double exprej(double c1, double c2);
double halfline(double a, double b, bool *lflipptr, bool binf);
double halfnorm(double c1, double c2);
double normrej(double c1, double c2);
double unifrej(double c1, double c2, double f);
double zkernel(double x);