SHEEP, CLASSI and STENSOR - Symbolic Computation System
SHEEP is a symbolic computation system designed primarily for tensor calculus in general relativity, but can also be used in other fields. SHEEP was written largely by Inge Frick in Stockholm in the late 1970s to early 1980s. It was used the LISP Algebraic Manipulator (LAM) by R.A. d’Inverno developed in the late 1960s. SHEEP was initially implemented in the assembly language MACRO-10 for DEC-10 computers, then in LISPs. The latest version is based on the Portable Standard LISP.
In SHEEP,
- tensors and tensor algorithms can be specified.
- tensor components can be manipulated.
- differentiate algebraic expressions can be read, written, simplified, substituted.
- perturbation calculations can be done.
- The Einstein tensor can be derived from a metric in a tetrad or in a coordinate frame.