(** Absolute value *)
Definition Babs abs_nan (x : binary_float) : binary_float :=
match x with
| B754_nan sx plx =>
let '(sres, plres) := abs_nan sx plx in B754_nan sres plres
| B754_infinity sx => B754_infinity false
| B754_finite sx mx ex Hx => B754_finite false mx ex Hx
| B754_zero sx => B754_zero false
end.

Theorem B2R_Babs :
forall abs_nan x,
B2R (Babs abs_nan x) = Rabs (B2R x).