第三种条件的三次样条函数插值的程序

unit unitp;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Math, TeEngine, Series, ExtCtrls, TeeProcs, Chart, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Chart1: TChart;
    Chart2: TChart;
    Chart3: TChart;
    Series1: TLineSeries;
    Series2: TLineSeries;
    Series3: TLineSeries;
    procedure Button1Click(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  procedure splsan(x,y,xx:array of double;var yy,dyy,ddyy:array of double);

implementation

{$R *.dfm}

procedure splsan(x,y,xx:array of double;var yy,dyy,ddyy:array of double);
var
  h0,h1,y0,y1,alpha,beta,u,g:double;
  i,n,j,m:integer;
  s,dy,ddy:array of double;
begin
  n:=length(x);
  m:=length(xx);
  setlength(s,n);
  setlength(ddy,n);
  setlength(dy,n);

  h0:=x[n-1]-x[n-2];
  y0:=y[n-1]-y[n-2];
  dy[0]:=0.0;
  ddy[0]:=0.0;
  ddy[n-1]:=0.0;
  s[0]:=1.0;
  s[n-1]:=1.0;
  alpha:=0.0;
  beta:=0.0;

  for j:=1 to n-1 do
  begin
    h1:=h0;
    y1:=y0;
    h0:=x[j]-x[j-1];