Неправильное написание функции

program lab;
 
function myfunc (var y,x: array of real;var n:integer;var a:real) : real;
var i : integer;
begin
   
   for i := 1 to n do
   begin
    if (x[i]>=a) then y[i]:=ln(abs(x[i]-cos(a*x[i])))
    else y[i]:=ln(abs(x[i]-sin(a*x[i])));
  end;
end;
 begin
   var n,i:integer;
   var a:real;var y,x:array[1..20]of real;
   writeln('Input n=');
   readln(n);
   writeln('Input a=');
   readln(a);
   writeln('Input an array:');
   for i:=1 to n do
   begin
      readln(y[i]);
   end;
   for i:=1 to n do
     write (myfunc(y,x,n,a));
   
   
   
end.

program lab;
 
const
  nmax = 100;
 
type
  vector = array [1..nmax] of real;
 
function myfunc(var y: vector; x: vector; n: integer; a: real): real;
var
  i: integer;
begin
  for i := 1 to n do
    if (x[i] >= a) then 
      y[i] := ln(abs(x[i] - cos(a * x[i])))
    else 
      y[i] := ln(abs(x[i] - sin(a * x[i])));
end;
 
var
  y1, x1: vector;
  n, i: integer;
  a: real;
 
begin
  writeln('Input n=');
  readln(n);
  writeln('Input a=');
  readln(a);
  writeln('Input an array:');
  for i := 1 to n do
    readln(x1[i]);
  for i := 1 to n do
  begin
    myfunc(y1, x1, n, a);
    write(y1[i]:8:2);
  end;
end.