CREATE TABLE table2 (
 "s_val" NUMERIC(6,2),
 "e_val" NUMERIC(6,2)
);

CREATE FUNCTION divide () RETURNS numeric AS
$body$
declare
  retval numeric(6,2);
  rec record;
begin
  SELECT * INTO rec FROM table2 LIMIT 0;
  rec.s_val = 100.0;
  rec.e_val = 101.0;

  -- returns correct value w/ casting:
  --retval = ((rec.s_val::numeric(6,2) - rec.e_val::numeric(6,2)) / rec.s_val::numeric(6,2)) * 100;

  -- returns incorrect value, as if fields have invalid datatypes:
  retval = ((rec.s_val - rec.e_val) / rec.s_val) * 100;

  return retval;
end
$body$
LANGUAGE 'plpgsql';

select version();
select divide();
drop function divide();
drop table table2;