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why3/examples/logic/real.why
2018-06-15 16:45:58 +02:00

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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