Re: Integration bug
- To: mathgroup at smc.vnet.net
- Subject: [mg38516] Re: Integration bug
- From: "Dana DeLouis" <delouis at bellsouth.net>
- Date: Fri, 20 Dec 2002 23:40:22 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Thanks for the nice debug code. Since the x was so close to y & z, I
tried your code with the letter t.
I got the same results. Both Upper & Lower case letters after ?t?
worked, but not for letters prior to "t".
I changed your code slightly to remove the Imaginary ?I? letter.
Removeall -> "All Global` variables Removed!"
lst = Drop[CharacterRange["A", "z"], {27, 32}];
lst = Drop[lst, {9}];
({#1, Integrate[Sin[#1 + t]/(#1 + t), {t, -Infinity, Infinity}]} & ) /@
ToExpression /@ lst
The examples so far used only single letters. I tried it with a
variable "junk1". The results that I show are the same. Upper & Lower
letters after "j" worked, but not for letters prior to "j".
{#, Integrate[Sin[# + Junk1]/(# + Junk1),
{Junk1, -Infinity, Infinity}]} & /@ ToExpression /@ lst
I have been looking everywhere, but cannot find the few other examples
that had this bug with the letter "d". However, now we see that the
problem appears to be worse than we thought. Sounds like a "serious"
bug to me.
--
Dana DeLouis
Windows XP
$VersionNumber -> 4.2
= = = = = = = = = = = = = = = = =
"Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de> wrote in message
news:atuocq$k3v$1 at smc.vnet.net...
> Hi,
>
> the bug is more funny try
>
> {#, Integrate[Sin[# + x]/(# + x), {x, -Infinity, Infinity}]} & /@
> ToExpression /@
> Join[Table[FromCharacterCode[i], {i, 65, 90}],
> Table[FromCharacterCode[i], {i, 97, 122}]]
>
> and find out that the integration for symbols
> E, X,Y,Z, y,z is correct for all other symbols
> one get 0
>
> Regards
> Jens
>
>
> Dana DeLouis wrote:
> >
> > I am new to Mathematica also, but I seem to recall a bug in the use
of
> > the variable ?d" before also. This was the first thing I thought
of.
> > Changing ?d" to something like ?z? gives the answer of Pi.
> >
> > Removeall
> >
> > All Global` variables Removed!
> >
> > $Version
> >
> > 4.2 for Microsoft Windows (June 5, 2002)
> >
> > Integrate[Sin[z + x]/(z + x), {x, -Infinity, Infinity}]
> >
> > Pi
> >
> > Integrate[Sin[d + x]/(d + x), {x, -Infinity, Infinity}]
> >
> > 0
> >
> > (Note: Removeall is my own function that removes all global
variables
> > and is included to show that all variables are cleared.)
> >
> > Dana DeLouis
> > Windows XP
> > $VersionNumber -> 4.2
> > = = = = = = = = = = = = = = = = =
> >
> >
> > "David W. Cantrell" <DWCantrell at sigmaxi.org> wrote in message
> > news:at4cv9$eta$1 at smc.vnet.net...
> > > Using version 4.1,
> > >
> > > Integral[Sin[x+d]/(x+d),{x,-Infinity,Infinity}] yields 0 .
> > >
> > > This is, of course, incorrect. (Does version 4.2 make this error
> > also?)
> > >
> > > Mathematica does Integral[Sin[x]/x,{x,-Infinity,Infinity}]
correctly
> > > however, yielding Pi, which should also be the answer for the
original
> > > integral (regardless of the value of d).
> > >
> > > Does anyone have an idea why Mathematica gets the original
integral
> > wrong?
> > >
> > > David Cantrell
> > >
> > > --