From: Christian Bauer Date: Fri, 11 May 2001 18:04:35 +0000 (+0000) Subject: dirac_trace() now takes three arguments X-Git-Tag: release_0-8-3~5 X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=ca09ead7889a10d651d0042cb4cf44ab4e8a177a;hp=8b3f3cb2d72aa91b9a635f63d5a4c9a24afa5b00 dirac_trace() now takes three arguments --- diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi index 5117d4ae..3cb6607c 100644 --- a/doc/tutorial/ginac.texi +++ b/doc/tutorial/ginac.texi @@ -2053,16 +2053,18 @@ To calculate the trace of an expression containing strings of Dirac gammas you use the function @example -ex dirac_trace(const ex & e, unsigned char rl = 0); +ex dirac_trace(const ex & e, unsigned char rl = 0, const ex & trONE = 4); @end example This function takes the trace of all gammas with the specified representation -label; gammas with other labels are left standing. The @code{dirac_trace()} -function is a linear functional that is equal to the usual trace only in -@math{D = 4} dimensions. In particular, the functional is not cyclic in -@math{D != 4} dimensions when acting on expressions containing @samp{gamma5}, -so it's not a proper trace. This @samp{gamma5} scheme is described in greater -detail in @cite{The Role of gamma5 in Dimensional Regularization}. +label; gammas with other labels are left standing. The last argument to +@code{dirac_trace()} is the value to be returned for the trace of the unity +element, which defaults to 4. The @code{dirac_trace()} function is a linear +functional that is equal to the usual trace only in @math{D = 4} dimensions. +In particular, the functional is not cyclic in @math{D != 4} dimensions when +acting on expressions containing @samp{gamma5}, so it's not a proper trace. +This @samp{gamma5} scheme is described in greater detail in +@cite{The Role of gamma5 in Dimensional Regularization}. The value of the trace itself is also usually different in 4 and in @math{D != 4} dimensions: