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Message-ID: <4b5157c30806220956p164d8346i3e832bc8b8666306@mail.gmail.com>
Date: Sun, 22 Jun 2008 18:56:22 +0200
From: "Paolo Donadeo" <p.donadeo@gmail.com>
To: "caml-list caml-list" <caml-list@yquem.inria.fr>
Subject: Strange behaviour of string_of_float
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X-Spam: no; 0.00; atan:01 val:01 val:01 serialize:01 printf:01 sprintf:01 1.0:98 behaviour:01 behaviour:01 string:02 string:02 workaround:03 float:03 float:03 let:03 

Today I noticed this strange behaviour of string_of_float:

Let's start with:

# let pi = 4.0 *. atan 1.0;;
val pi : float = 3.14159265358979312
# let (|>) x f = f x;;
val ( |> ) : 'a -> ('a -> 'b) -> 'b = <fun>

Ok, I want to serialize pi:

# (pi |> string_of_float |> float_of_string) -. pi;;
- : float = 2.06945571790129179e-13

string_of_float is not the inverse of float_of_string, at least in this example.

Is this correct? It's not a problem at all, I used this workaround:

# let my_string_of_float = Printf.sprintf "%.1000g";;
val my_string_of_float : float -> string = <fun>

# (pi |> my_string_of_float |> float_of_string) -. pi;;
- : float = 0.


-- 
Paolo
~
~
:wq