#### 7.2.7.1 ring declarations (plural)

Syntax:
  `ring` name `= (` coefficient_field `),` `(` names_of_ring_variables `),` `(` ordering `);`
Default:
  `32003,(x,y,z),(dp,C);`
Purpose:
  declares a ring and sets it as the actual basering.

The coefficient_field is given by one of the following:

1. a non-negative int_expression less or equal 2147483647.
2. an expression_list of an int_expression and one or more names.
3. the name `real`.
4. an expression_list of the name `real` and an int_expression.
5. an expression_list of the name `complex`, an optional int_expression and a name.

'names_of_ring_variables' must be a list of names or indexed names.

'ordering' is a list of block orderings where each block ordering is either

1. `lp`, `dp`, `Dp`, optionally followed by a size parameter in parentheses.

2. `wp`, `Wp`, or `a` followed by a weight vector given as an intvec_expression in parentheses.

3. `M` followed by an intmat_expression in parentheses.

4. `c` or `C`.

As long as all non-commuting variables are global, any ordering may be used. In graded commutative algebras, one may also use `ls, ds, Ds, ws`, and `Ws`.

If one of coefficient_field, names_of_ring_variables, and ordering consists of only one entry, the parentheses around this entry may be omitted.

In order to create a non-commutative structure over a commutative ring, use nc_algebra.

User manual for Singular version 4-0-3, 2016, generated by texi2html.