Require Import Rbasic_fun.
Ltac split_case_Rabs :=
match goal with
| |- context [(Rcase_abs ?X1)] =>
case (Rcase_abs X1); try split_case_Rabs
end.
Ltac split_Rabs :=
match goal with
| id:context [(Rabs _)] |- _ => generalize id; clear id; try split_Rabs
| |- context [(Rabs ?X1)] =>
unfold Rabs in |- *; try split_case_Rabs; intros
end.