Name: rolf_at_HIDDEN-E-MAIL Date: 12/08/04-11:45:15 PM Z


Dear Jinghantao,
yes, unfortunately there is a bug right now when calling
Tr directly on on unsimplified noncommutative expressions.
Please use DiracSimplify or Calc first.
E.g., defining

tr = TR[Calc[#]]& ;

and using tr instead of TR will give the correct result
for calculating traces.

Regards,

Rolf Mertig

GluonVision GmbH
Berlin
Germany

>feyncalc,hello
> when i use trace fuction to calculate the >expression:Tr[(GA[j].GS[q] - GS[q].GA[j]).(GA[i].GS[q] - >GS[q].GA[i])],the result is null. But for the >expression:Tr[DiracSimplify[(GA[j].GS[q] - >GS[q].GA[j]).(GA[i].GS[q] - GS[q].GA[i])]],the result isnot >null, furthermore, the second expression’s result is the same >to my manuscript. why? Could you give me some help? thanks >very much.
>
>        jinghantao
>        [jinght_at_HIDDEN-E-MAIL]
>          2004-12-02