IF SIGN(c3_rec.amount) = -1 then
-- c3_rec.amount is variable from cursor

PLS-00103: Encountered the symbol "SIGN" when expecting one of the following:
:= . ( @ % ;
The symbol ":=" was substituted for "SIGN" to continue.

SQL> set serveroutput on
SQL> declare
  2    cursor c_test is
  3      select level - 2 val from dual connect by level <= 3;
  4  begin
  5    for r_test in c_test loop
  6     if sign( r_test.val ) = -1 then dbms_output.put_line( to_char(r_test.val)||' is negative' );
  7     else dbms_output.put_line( to_char(r_test.val)||' is positive' );
  8     end if;
  9    end loop;
 10  end;
 11  /
-1 is negative
0 is positive
1 is positive

PL/SQL procedure successfully completed.

SQL>