LaGrange.pas

Uses crt;

Function calculateX(xFrom, i, step : real) : real;
Begin
    calculateX := xFrom + i * step;
End;

Function yFormula(x : real) : real;
Begin
    yFormula := exp(-(x - 2) * (x - 2));
End;

Procedure printLBase(i, n : integer; xFrom, step : real);
Var j : integer;
Begin
    write('(');
    For j := 0 To n Do Begin
        If (j <> i) Then
            write('(x - ', calculateX(xFrom, j, step):0:6, ')');
    End;
    write(')/(');
    For j := 0 To n Do Begin
        If (j <> i) Then
            write('(', calculateX(xFrom, i, step):0:6,' - ', calculateX(xFrom, j, step):0:6, ')');
    End;
    write(')');
End;

Var
    xFrom, xTo, step : real;
    i, n : integer;
Begin
    xFrom := 2;
    xTo := 4;
    step := 0.2;

    n := Trunc((xTo - xFrom) / step);

    write('L(x) = ');
    For i := 0 To n Do Begin
        printLBase(i, n, xFrom, step);
        If (i < n) Then
            write(' + ');
    End;
End.