// spline test   g++ -std=c++11 gsl_spline.cpp `gsl-config --libs`
#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
// home made call to GSL spline
#include "gsl_spline.hpp"

typedef std::vector<double> vec;

void output(const vec& x, const vec y)
{
  std::cout<<std::fixed<<std::setprecision(8);
  for(size_t i=0;i<x.size();++i)
    std::cout<<x[i]<<" "<<y[i]<<"\n";
  std::cout<<"\n\n\n";
}

int main(){
  vec x(10),y(10); // known points (x,y)
  double t;
  t=-5.0;
  for(unsigned i=0;i<x.size();++i){  // you could use std::generate 
    x[i] = t; 
    y[i] = 10.0-t*t;
    t += 1.0;
  }
  y[4] += 10.0; // lift one point up to demonstrate locality/nonlocality
  output(x,y);
  
  // interpolated points xx
  vec xx(100),yy(100);
  double dx = (x[x.size()-1]-x[0])/(xx.size()-1);
  for(unsigned i=0;i<xx.size();++i){ xx[i] = x[0]+i*dx;}

  // interpolate using natural cubic spline
  my::spline(x,y,xx,yy,"cspline");
  output(xx,yy);

  // interpolate using natural Akima spline
  my::spline(x,y,xx,yy,"Akima");
  output(xx,yy);
}
// a.out>tt 
// gnuplot
// p 'tt' i 0 w p pt 7 ps 1.5 t'known points','' i 1 w lp pt 8 t'cubic','' i 2 w lp pt 12 t'akima'