**Next message:**Vladyslav Shtabovenko: "Re: An Bug on infinity cancellation at oneloop???"**Previous message:**Lingxiao Xu: "Re: An Bug on infinity cancellation at oneloop???"**In reply to:**Sun: "A serious BUG in FeynCalc 8.20"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

Hi,

* > Before we load Feyncalc and Feynarts, all is ok:
*

* > Conjugate[Exp[i*Pi/4]]=Exp[-i*Pi/4](Normal),
*

* > but when the packages(Feyncalc and Feynarts) are both loaded, I find
*

this BUG appear:

* > Conjugate[Exp[i*Pi/4]]=Exp[i*Pi/4](BUG!).
*

* > when I set $LoadPhi=False and $LoadFeynArts=False
*

* > and execute <<HighEnergyPhysics`FeynCalc`,this time I only load
*

FeynCalc, I find this BUG disappear again:

* > Conjugate[Exp[i*Pi/4]]=Exp[-i*Pi/4](Normal).
*

The problem is that in the present state (at least in Mathematica 9)

FeynArts and Phi don't really work with FeynCalc. When you load them

nevertheless, you get a bunch of error messages related to shadowing.

As you correctly observed, using

$LoadPhi=False

$LoadFeynArts=False

<<HighEnergyPhysics`FeynCalc`

avoids these problems.

*> Another question is:
*

*> when use "ComplexConjugate" to replace "Conjugate" I find another question.
*

*> ComplexConjugate[Exp[i*Pi/4]]=Exp[-i*Pi/4](Normal)
*

*> ComplexConjugate[5^i]=5^i(BUG?)
*

*> please contact me soon!
*

*> Email:qfsun@mail.ustc.edu.cn
*

*> Thank you!
*

*>
*

I think that this behavior of ComplexConjugate is not a bug. The

description of the command (?ComplexConjugate) says

---------------------------------------------------------

ComplexConjugate[expr] complex conjugates expr.

It operates on Fermion-lines, i.e., products

of Spinor[..] .DiracMatrix[..] . Spinor[..].

For taking the spin sum (i.e. constructing the traces) use

FermionSpinSum.

WARNING: In expr should be NO explicit I in denominators!

---------------------------------------------------------

Now if you apply ComplexConjugate to 5^I, you are explicitly

ignoring the warning, which is why you are getting a wrong result.

I would not use ComplexConjugate for anything that is not a fermion line

or contains explicit I's.

Cheers,

Vladyslav

**Next message:**Vladyslav Shtabovenko: "Re: An Bug on infinity cancellation at oneloop???"**Previous message:**Lingxiao Xu: "Re: An Bug on infinity cancellation at oneloop???"**In reply to:**Sun: "A serious BUG in FeynCalc 8.20"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

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