лаба №1 крэс-05 / nash_log

{Џа®Ја ¬¬  Ї®бв஥­Ёп Ї®«Ё­®¬  ‹ Ја ­¦ 
ђ Ў®вг ўлЇ®«­Ё«Ё ‹лвЄЁ­ Џ.‚., ‹г§Ё­ Њ.Њ. Ја Ђ’-01-2}
program Lagrang;
uses graph;
const n=8;
var x,y:array[0..n]of real;
   i,j,t,m,b:integer;
   w:real;

function lagr(x1:real):real;
   var i,j:integer;
   ln,q,p:real;
  begin
     ln:=0;
     for i:=0 to n do
     begin
       q:=1;
       p:=1;
        for j:=0 to n do
         begin
           if not (i=j) then p:=p*(x1-x[j]);
           if not (i=j) then  q:=q*(x[i]-x[j]);
          end;
       ln:=ln+y[i]*p/q;
     end;
   lagr:=ln;
  end;

  begin
    for i:=0 to n do x[i]:=-4+i;
    y[0]:=0;
    y[1]:=0;
    y[2]:=1;
    y[3]:=0;
    y[4]:=0;
    y[5]:=0;
    y[6]:=-1;
    y[7]:=0;
    y[8]:=0;

    m:=detect;
    initgraph(m,b,'m:\bgi');
    line(360,0,360,340);
    line(0,170,720,170);
    for i:=50 to 700 do
    begin
      t:=round(-170*(lagr(6*i/360-6))/4+170);
      putpixel(i,t,3);
    end;
 readln;
 closegraph;
end.