Tag Interpolate -- Asymptote Gallery

🔗Asymptote Gallery Tagged by “Interpolate” #140

🔗graph-fig028

Figure graph 028 Generated with Asymptote

import graph;
size(10cm);

xaxis("$x$", -2*pi,2*pi, Arrow);
yaxis("$y$", -4,4, Arrow);

typedef real realfcn(real); // Define new type: real function of real

realfcn TPC(int n) { //Return Taylor polynomial (degrees 2*n) of cos
  return new real(real x) {
    return sum(sequence(new real(int m){return (-1)^m*x^(2*m)/gamma(2*m+1);}, n+1));
  };
}
draw(graph(cos,-2pi,2pi), linewidth(2bp), legend="$\cos$");

int n=6; // Number of curves
pen[] p={palered, lightred, red, blue, purple, green};
p.cyclic=true; // p[6]=p[0], p[7]=p[1], etc...

for (int i=0; i < n; ++i) {
  draw(graph(TPC(i),-2*pi,2*pi), bp+p[i], legend="$T_{"+(string)i+"}$");
}

xlimits(-2*pi,2*pi, Crop);
ylimits(-4,4, Crop);

attach(legend(linelength=3mm),point(E),5E);
shipout(bbox(Fill(lightgrey)));

🔗graph-fig030

Figure graph 030 Generated with Asymptote

Other examples of interpolations can be found here.

import graph;
unitsize(1cm);

typedef real hermite(real);

/**
 * Retourne la fonction polynôme de Hermite
 * passant par les points m(x_i,y_i) de nombre dérivée d_i en ce point.
 * Return Hermite polynomial interpolation function
 * passing by the points m (x_i, y_i) of derived number d_i in this point.
 **/
hermite hermite(pair [] m, real [] d)
{
  return new real(real x){
    int n=m.length;
    if (n != d.length) abort("Hermite: nombres de paramètres incorrectes.");
    real q,qk,s,y=0;
    for (int k=0; k<n ; ++k) {
      real q=1, qk=1, s=0;
      for (int j=0; j<n; ++j)
        {
          if (j!=k){
            q=q*(x-m[j].x)^2;
            qk=qk*(m[k].x-m[j].x)^2;
            s=s+1/(m[k].x-m[j].x);
          }
        }
      y=y+q/qk*(m[k].y+(x-m[k].x)*(d[k]-2*s*m[k].y));
    }
    return y;
  };
}

pair[] m;
real[] d;
int nbpt=5;
real xmin=-2pi,
xmax=2pi,
l=xmax-xmin,
step=l/(nbpt+1);
for (int i=1; i<=nbpt; ++i)
  {
    real x=xmin+i*step;
    m.push((x,sin(x)));
    draw(m[m.length-1],linewidth(2mm));
    d.push(cos(x));
  }

xlimits(-2pi,2pi);
ylimits(-2,2);
xaxis("$x$",BottomTop,Ticks);
yaxis("$y$",LeftRight,Ticks);

draw(graph(sin,xmin,xmax),1mm+.8red,"$x\longmapsto{}\sin x$");
draw(graph(hermite(m,d),xmin,xmax),"$x\longmapsto{}H(x)$");

attach(legend(),point(10S),30S);

🔗graph-fig031

Figure graph 031 Generated with Asymptote

Show graph/fig0320.asy on Github.
Generated with Asymptote 3.00-0.
Categories : Examples 2D | Graph.asy
Tags : #Graph | #Interpolate | #Function (drawing) | #Legend

import graph;
import interpolate;

size(15cm,10cm,IgnoreAspect);

real[] xpt,ypt;
real [] xpt={1, 2, 4, 5, 7, 8, 10};
real [] ypt={1, 2, 2, 3, 1, 0.5, 3};


horner h=diffdiv(xpt,ypt);
fhorner L=fhorner(h);

scale(false,true);

pen p=linewidth(1);

draw(graph(L,min(xpt),max(xpt)),dashed+black+p,"Lagrange interpolation");
draw(graph(xpt,ypt,Hermite(natural)),red+p,"natural spline");
draw(graph(xpt,ypt,Hermite(monotonic)),blue+p,"monotone spline");
xaxis("$x$",BottomTop,LeftTicks(Step=1,step=0.25));
yaxis("$y$",LeftRight,RightTicks(Step=5));
dot(pairs(xpt,ypt),4bp+0.7black);

attach(legend(),point(10S),30S);