PascalABC.NET does not count logarithm

Question

Pascal

In the lab, you need to calculate the logarithm.
I use a function from the base library Ln .
I pass 1 as an argument (in a variable).
Outputs : -1.11022302462516E-16.

What to do?

Answer 1

       Most likely, he just gave you an approximate value and you need to round it up, because you don’t store 1 in the variable.
       Check again what you have stored in the variable, if it doesn’t help, then throw off the program code and I’ll take a look.
       For example, the code below returns 0

var i: double;
begin
  i:=1;
  writeln(Ln(i));	
end.

Answer 2

All finally figured out!!!
       There is a small error in the calculation of the tangent:
(so the value of Pi is constant and equal in the standard library PABCSystem Pi = 3.141592653589793)
n1 + n2 = 0.785398163397448;
tan(n1 + n2)=1.0000...        Most likely that is why, as a result of calculating the value of the logarithm, we get an approximate value of 0.0000000000000001...        I think that such an error is quite normal... PS        I immediately answer your comment: "I understand, shitcode, but it's just laba))" I advise you to immediately download skills on writing good code on the labs, although the code is not particularly bad. Thank you for your attention and success in your studies!

Answer 3

///Возвращает интеграл
function Integral(var x: integer; n: integer): real;
var
  tng, temp: real;
  n1, n2: real;
begin
  if n = 1 then
  begin
    n1 := (Pi / 4);
    n2 := (x / 2);
    tng := tan(n1 + n2);
    temp := ln(tng);
    integral := temp;
    //компилятор неверно считает логарифм!!!
  end;
  if n = 0 then
    
    integral := x;
  if n >= 2 then
    integral := ((1 / n - 1) * (sin(x)) / power(cos(x), n - 1)) + (((n - 2) / (n - 1)) * integral(x, n - 2))
else
  
  
end;

//Разобраться со ссылками на параметры

var
  x: integer;
  n: integer;

begin
  writeln('read(x)');
  read(x);
  writeln('readln(n)');
  readln(n);
  
  //writeln('Интеграл dx/(cos', x, ')^', n, '=', integral(x, n));
end.

There task is simple. Calculate the integral. It seems that if you give n=1, then it should give a logarithm, and since I chose the values ​​x=0 n=1 for the test, the program should return 0, but .... alas.