Make it as simple as possible, but not simpler: The Programming Language Oberon

PROCEDURE Reci(x: REAL): REAL; (*0 < x < 2*)

VAR y, c: REAL;

BEGIN y := 1.0; c := 1.0 – x;

WHILE c > e DO

(* y×x = 1-c, 0 < |c| < 1 *)

y := y × (1.0+c); c := c×c

END

(* (1-e)/x <= y < 1/x *) RETURN y

END Reci