/* deriv.h  compute formulas for numerical derivatives          */
/*          returns  npoints  values in  a  or  c               */
/*          0 <= point < npoints                                */
void deriv(int order, int npoints, int point, int *a, int *bb);
/* c[point][] = (1.0/((double)bb*h^order))*a[]                  */
void rderiv(int order, int npoints, int point, double h, double c[]);
/* c includes bb and h^order                                    */
/* derivative of f(x)    = c[0]*f(x+(0-point)*h) +              */
/*                         c[1]*f(x+(1-point)*h) +              */
/*                         c[2]*f(x+(2-point)*h) + ... +        */
/*                 c[npoints-1]*f(x+(npoints-1-point)*h         */
/*                                                              */
/* nuderiv give x values, not uniformly spaced, rather than h   */
void nuderiv(int order, int npoints, int point, double x[], double c[]);