theory CosineSingle

use real.Real
use real.Abs
use real.Trigonometry

(* approximation of cosine function by 1 - x^2 / 2 on interval [-1/32; 1/32] *)



lemma MethodError: forall x:real. abs x <= 0x1p-5 ->
  abs (1.0 - 0.5 * (x * x) - cos x) <= 0x1p-24
(* this one is proved in Coq + interval tactics *)


end


