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authorGravatar desmettr <desmettr@85f007b7-540e-0410-9357-904b9bb8a0f7>2002-07-16 09:02:39 +0000
committerGravatar desmettr <desmettr@85f007b7-540e-0410-9357-904b9bb8a0f7>2002-07-16 09:02:39 +0000
commit1e558a3ce46468154c719eba3f6812be23ab49d7 (patch)
tree32e98c4344acba472f2099239787086cd2400325 /theories/Reals/Ranalysis4.v
parent62c194585824256fa8f5967e079388c8d2e703ad (diff)
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git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@2879 85f007b7-540e-0410-9357-904b9bb8a0f7
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diff --git a/theories/Reals/Ranalysis4.v b/theories/Reals/Ranalysis4.v
index a3ce1e4d1..afd65a500 100644
--- a/theories/Reals/Ranalysis4.v
+++ b/theories/Reals/Ranalysis4.v
@@ -16,9 +16,25 @@ Require Rderiv.
Require DiscrR.
Require Rtrigo.
Require Ranalysis1.
+Require R_sqrt.
Require Ranalysis2.
Require Ranalysis3.
+(* sqrt *)
+Axiom derivable_pt_lim_sqrt : (x:R) ``0<x`` -> (derivable_pt_lim sqrt x ``/(2*(sqrt x))``).
+
+Lemma derivable_pt_sqrt : (x:R) ``0<x`` -> (derivable_pt sqrt x).
+Unfold derivable_pt; Intros.
+Apply Specif.existT with ``/(2*(sqrt x))``.
+Apply derivable_pt_lim_sqrt; Assumption.
+Qed.
+
+Lemma derive_pt_sqrt : (x:R;pr:``0<x``) ``(derive_pt sqrt x (derivable_pt_sqrt ? pr)) == /(2*(sqrt x))``.
+Intros.
+Apply derive_pt_eq_0.
+Apply derivable_pt_lim_sqrt; Assumption.
+Qed.
+
(**********)
Lemma derivable_pt_inv : (f:R->R;x:R) ``(f x)<>0`` -> (derivable_pt f x) -> (derivable_pt (inv_fct f) x).
Intros; Cut (derivable_pt (div_fct (fct_cte R1) f) x) -> (derivable_pt (inv_fct f) x).