[原创]反渐开线函数

根据迭代公式写的反渐开线计算函数

//x is an RAD value
function ArcInv(x:double):double;
const
  MAXError=0.00000001;
  MAXCount=10000;
var
  x1,x2,error:double;
  num:integer;
begin
  x1:=3*x;
  x1:=exp(ln(x1)/3);        //x=(3x)^(1/3)
  error:=1;         //maximum of error
  num:=0;           //counter of iterative
  while (error>MAXError) and (num<MAXCount) do
  begin
    x2:=arccos(sin(x1)/(x+x1));
    error:=abs(x2-x1);  inc(num);
    x1:=x2;
  end;
  Result:=x1;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.Text:=Floattostr(arcinv(0.016516924))
end;