27 Jun
2003
27 Jun
'03
3:52 p.m.
Hi! On Fri, Jun 27, 2003 at 06:06:13PM +0800, Yong Xiao wrote:
indexed(Y,sy_symm(),i_,m_,n_)*indexed(t,n_,j_) ==indexed(Y,sy_symm(),j_,n_,m_)*indexed(t,n_,i_)
This assumes that the first index ('n') of the 't' is equal to the last index of the 'Y'. However, with sy_symm(), GiNaC will rearrange the indices into a canonical, but unpredictable, order. So you have to drop the sy_symm() in the subs() and provide a list of substitutions for all three possible positions of the common index 'n_' in 'Y'. You also don't need the subs_algebraic. Bye, Christian -- / Physics is an algorithm \/ http://www.uni-mainz.de/~bauec002/