- Full Simplification of Symbolic Tensor Expressions.
- i.e. with symbolic indices on tensors. Any index symmetries are allowed,
and consequences undestood, eg that A_{ij}S^{ij}-0, if (A) S are (anti)
symmetric, respectively.
- Noncommutative- and Operator Algebra
- Handling octonians, Clifford/Grassman algebra, Poisson brackets, variations,
difforms,...
- Kaluza-Klein, Supergravity, Spinors.
- Splitting into any number of spubspaces, multiple indextypes/conventions for
these subspaces, Fiertz-transformations, gamma algebra and trace for any
dimension/metric, ...
- Sum-Substitutor fully Exploit Trig- and other Sumrelations.
- Eg -cos^6x sin^2x + cos^6x - cos^2x sin^7x + sin^7x -> sin^9x +cos^8x
Other systems tend towards pure sin (or cos) results, while STENSOR returns
the minimal mixture! From this cyclic Riemann symmetry (sumrelation)
STENSOR derived the seemingly new identities: R_{ijkl}R_{klmn}R_{mnij} =
4R_{ijkl}R_{ikmn}R_{jmln} = 2R_{ijkl}R_{ikmn}R_{jlmn} from the (accidental)
LHS input.
- Generate Tensor Algorithms for Component Computation
- From symbolic formulae, algorithms are generated that compute tensor
components often faster than handcoded algorithms. Especially this is done
in symbiosis with the relativity system SHEEP.
- Disk-Bucketing for Multi-Million Term Calculations.
- Expression parts (buckets) can be automatically shuffled to/from disk at
need. So was the general Ricci-tensor in 5 dimensions computed: R_{00} had
263,598 terms, exceeding eg Reduce/Macsyma capability by orders of magnitude.
Time was a reasonable 100 h. with a negligible part spent in disk i/o,
so much larger computations than this are possible.
Schoonschip and FORM offer this facility as well.
- User Interface.
- Formulae input close to textbook conventions
- Do-What-I-Mean toplevel with menus
- History and modification mechanism a la unix shell
- On line help that looks up appropriate documentation
- Extensively commented lectues/demos that yoy step through interactively
- A TeX mode cause STENSOR create a session file you can send directly to TeX
- User guide, which ahs been produced by STENSOR in its TeX mode
- Reference Manual, 120 pages.
- STENSOR/SHEEP can run alone or inside Reduce, fully exploiting its features like GCD and factoring.

- Machines
- VAX(VMS/U-ix), Orion (HLH ltd), SUN, DEC/VAX workstations, IBM 3090, ATARI ST, AMIGA, Desktops IBM 386, 486, and MacIntosh.

Lars Hornfeldt

Institute of Theoretical Physics

University of Stockholm

Vanadisvagen 9

S-113 46 STOCKHOLM, S W E D E N

Email: lh@vand.physto.se

Special Purpose Systems