Лабораторная работа1 / FORMLAGR

program FormLagr;

const
  Nmax = 50;

type
  massiv = array[0..Nmax] of real;

var
  X,Y,D: massiv;
  P,x0: Real;
  i,j,n: Integer;
  exit:String;

function Lagr(x0:real):Real;
var
  s:real;
begin
  s:=0;
  for i:=0 to n do
    s:=s+Y[i]/((x0-X[i])*D[i]+0);
  lagr:=P*s;
end;
  
begin
  Write('n= ');
  ReadLn(n);
  for i:=0 to n do begin
    Write('x',i,'= ');
    ReadLn(X[i]);
    Write('y',i,'= ');
    ReadLn(Y[i]);
  end;
  {D}
  for i:=0 to n do begin
    D[i]:=1;
    for j:=0 to n do
      if j<>i then
        D[i]:=D[i]*(X[i]-X[j]);
  end; {D}
  repeat
    Write('x= ');
    ReadLn(x0);
    {P}
    P:=1;
    for i:=0 to n do
      P:=P*(x0-X[i]); {P}
    WriteLn('y= ',lagr(x0):3:3);
  until false;
end.