int fileopen(void);

double *vector(long size);
void free_vector(double *v);
double **matrix(long rows, long cols);
void free_matrix(double **m);
int *ivector(long nh);
void free_ivector(int *v);

void  ludcmp(double **, int n, int *, double *);
void lubksb(double **, int n, int *, double []);
void usrfun(double *x,int n,double *fvec,double **fjac);
void mnewt(int ntrial, double x[], int n, double tolx, double tolf);

static double sqrarg;
#define SQR(a) ((sqrarg=(a)) == 0.0 ? 0.0 : sqrarg*sqrarg)