Jython

On Monday 15 November 2004 16:32, Widhalm, Eric wrote:
> > could you tell me if  the following  code
> >
> >  >>from java.lang import Math
> >  >>g = Math.log(-1.0)
> >  >>print (g==111.0)
> >
> > 1
> >
> > highlights a bug or is an (un)expected behaviour of the rich
> > comparison?
>
> Nicola, the return value will either be 0 or 1, representing boolean values
> true or false.
> In this case, -1 is != 111.0, so you get back 1, representing false.

Grunt ??? 
1 = false, 0 = true ??? 

So if I write:

print(111.0 == 111.0)

it should print 0 ?????

Nono, I really believe something is wrong here

Werner,

I don't quite get your meaning, but maybe this is clearer:

Jython 2.1 on java1.3.1_01 (JIT: null)
Type "copyright", "credits" or "license" for more information.
>>> from java.lang.Float import NaN
>>> NaN =3D=3D 1
1
>>>

From the JLS:

"NaN is unordered, so the numerical comparison operators <, <=3D, >, and =

>=3D return false if either or both operands are NaN (=A715.20.1). The=20
equality operator =3D=3D returns false if either operand is NaN, and the =

inequality operator !=3D returns true if either operand is NaN =
(=A715.21.1).=20
In particular, x!=3Dx is true if and only if x is NaN, and (x<y) =3D=3D =
!(x>=3Dy)=20
will be false if x or y is NaN."

http://java.sun.com/docs/books/jls/second_edition/html/typesValues.doc.ht=
ml#16083

a.k.a. Bug, IMHO.

-Clark

-----Original Message-----
From: On Behalf Of Widhalm, Eric
Sent: Monday, November 15, 2004 10:32 AM
Subject: RE: [Jython-users] (NaN =3D=3D 111.0 ) returns 1 !

> could you tell me if  the following  code
>=20
>  >>from java.lang import Math
>  >>g =3D Math.log(-1.0)
>  >>print (g=3D=3D111.0)
> 1
>=20
> highlights a bug or is an (un)expected behaviour of the rich
> comparison?

Nicola, the return value will either be 0 or 1, representing boolean =
values true or false. In this case, -1 is !=3D 111.0, so you get back 1, =
representing false.

-Eric