/*
 *** spline.h -- header file for spline functions, see spline.c 
 */

#ifndef SPLINE_H
#define SPLINE_H

#include        "error.h"
#define        spline_error(mesg)        (*error_handler)(__FILE__,__LINE__,mesg)

typedef struct {
  /* See Atkinson:
     Intro Numer Anal, 2nd Ed'n, pp. 166-173 */
  int    length;
  double *xlist;    /* list of knots */
  double *ylist;    /* values interpolated */
  double *Mlist;    /* 2nd derivatives at knots */
} spline;


/* spline_create -- allocates spline structure 
      with the desired length */
spline *spline_create(int length);

/* spline_destroy -- frees spline structure memory */
void    spline_destroy(spline *s);

/* spline_print -- prints a representation of 
      the spline s to the stream fp */
void spline_print(FILE *fp, spline *s);

/* spline_read -- reads a representation of
      a spline from stream fp and return the spline */
spline *spline_read(FILE *fp);

/* spline_setxy -- copies the knot and interpolation 
      values into xlist and ylist */
spline *spline_setxy(spline *s, 
                     double x[], double y[], int length);

/* spline_eval -- evaluates spline s at point t */
double      spline_eval(spline *s, double t);

/* spline_make_natural -- constructs natural spline
      using knots and values (xlist & ylist resp.) in s */
spline *spline_make_natural(spline *s);

/* spline_make_periodic -- constructs periodic spline
      using knots and values in s;
      must have ylist[length-1] == ylist[0] 
      for periodicity */
spline *spline_make_periodic(spline *s);

/* spline_make_clamped -- constructs clamped spline
      using knots and values in s, but with
      end-point derivatives dy0 at xlist[0] and
      dy_end at xlist[length-1] */
spline *spline_make_clamped(spline *s,
                            double dy0, double dy_end);

#endif /* SPLINE_H */