Tensors for dummies



The full blown elasticity stuff that Richard and Viktor sent me looks a 
bit daunting so I thought I'd start by trying to understand how maxima 
deals with some more basic examples but I've got stuck on example 1.1.

I think I need the "Tensors for Dummies" version of the manual.

Would someone please explain the what is happening in following example?

(%i10) load(itensor);
(%o10)   /usr/local/share/maxima/5.9.2.2cvs/share/tensor/itensor.lisp
(%i11) idim(2);
(%o11)                               done
(%i12) showcomps(a([i])*b([j]));
                                    [ a  b   b  a  ]
                                    [  1  1   1  2 ]
(%t12)                     a  b  = [              ]
                             i  j   [ a  b   a  b  ]
                                    [  1  2   2  2 ]
(%o12)                               false

That is what I expected.


(%i13) showcomps(a([i])*b([i]));
                                    [ a  b   a  b  ]
                                    [  1  1   2  2 ]
(%t13)                     a  b  = [              ]
                             i  i   [ a  b   a  b  ]
                                    [  1  1   2  2 ]
(%o13)                               false


I expected this answer to be a1b1 + a2b2. I see that the off-diagonal 
indices are different to the first example but can't see how to 
interpret the result as a1b1 + a2b2 (if that's really what it should be).

Also what does the "false" in the output mean?

Thanks
Glenn

-- 
Glenn Ramsey  07 8627077
http://www.componic.co.nz