From: John-John Tedro <johnjohn.tedro@...>
Date: 2011-08-14T06:02:12+09:00
Subject: Re: Why this?

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On Sat, Aug 13, 2011 at 9:28 PM, =D0=9D=D0=B8=D0=BA=D0=BE=D0=BB=D0=B0=D0=B9=
 <Godsent@mail.ru> wrote:

>
>
> -------- Original Message --------
> Subject:        Why this?
> Date:   Sat, 13 Aug 2011 22:20:04 +0300
> From:   =D0=9D=D0=B8=D0=BA=D0=BE=D0=BB=D0=B0=D0=B9 <godsent@tut.by>
> To:     ruby-talk@ruby-lang.org
>
>
>
> Hallow, can anybody explain me that?
> a =3D (10**2 + 5**2)                  #=3D>  125
> b =3D Math.hypot(10, 5)**2        #=3D>  125.0
>


> a =3D=3D b                                     #=3D>false
>

http://ruby-doc.org/core/classes/Fixnum.html#M001090
They are not numerically equal.
b is not exactly 125.0, I'm not into details about ruby's float
implementation, but the result simply isn't 100% accurate. Try a.to_f =3D=
=3D
b.round


> a.to_f =3D=3D b                              #=3D>  false
>

Same as above.


> 125.0 =3D=3D 125                          #=3D>  true
>

http://www.ruby-doc.org/core/classes/Float.html#M000127

The 125.0 declaration is accurate, so numerical equality is true. As the
documentation says, this is not an eql? check (i.e. does not have to be sam=
e
type).


> 125.0.to_f =3D=3D 125                   #=3D>  true
>
>
Same as above.

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