(****************************************************************************  IEEE754  :  Rpow  Laurent Thery  ***************************************************************************** Definition of an exponential function over relative numbers *)
Require Export Omega.
Require Export Digit.
(* We have already an exponential over natural number, we prove some basic properties for this function *)
simpl in |- *; auto with real.
Qed.
simpl in |- *; auto with real.
Qed.
intros e n; elim n; simpl in |- *; auto with real.
Qed.
intros e n; elim n; simpl in |- *; auto with real.
intros n0 H' m; rewrite H'; auto with real.
Qed.
Hint Resolve pow_O pow_1 pow_NR0 pow_add: real.
intros e n; elim n; simpl in |- *; auto with real.
intros n0 H' m H'0.
rewrite Rmult_assoc; rewrite <- H'; auto.
Qed.
intros e n; elim n; simpl in |- *; auto with real.
intros n0 H' H'0; replace 0%R with (e * 0)%R; auto with real.
Qed.
Hint Resolve pow_lt: real.
intros e n; elim n; simpl in |- *; auto with real.
intros H' H'0; Contradict H'0; auto with arith.
intros n0; case n0.
simpl in |- *; rewrite Rmult_1_r; auto.
intros n1 H' H'0 H'1.
replace 1%R with (1 * 1)%R; auto with real.
apply Rlt_trans with (r2 := (e * 1)%R); auto with real.
apply Rmult_lt_compat_l; auto with real.
apply Rlt_trans with (r2 := 1%R); auto with real.
apply H'; auto with arith.
Qed.
Hint Resolve Rlt_pow_R1: real.

Theorem Rlt_pow :
forall (e : R) (n m : nat), (1 < e)%R -> n < m -> (e ^ n < e ^ m)%R.