Variable lists

 

A variable list is an unordered subset of the variables of a ring. Variable lists are used by the command jacob to determine which variables to differentiate with respect to, and the commands coef, stdpart, inpart, std-minimal, k-basis, and truncate which divide the variables into the ``essential'' variables and the ``parameters'' or ``coefficients''.

A variable list consists of items separated by blanks. An item in the variable list is one of the following:

• ring variables, e.g. a, x[i+1], d[i,j].
• ring variable .. ring variable (range).

Duplicates in the list are not counted and ranges are determined by the order of the variables in the ring.

Using special characters in response to a variable list request has the following meaning:

• <return> indicates the default and denotes the variables in the first block.
• ! list An exclamation mark at the beginning of a list means complement the set.
• ! Denotes the set of all variables in the ring.
• This is the line continuation character. If this is entered, preceded by a blank space, you will be prompted to continue entering the variable list on the next line (which may also be continued with , etc.)

For example, suppose the ring variables in the current ring, in the order they were given in the ring command, are ``xyzabcdef'', where ``xyz'' are the three variables in the first block, and ``abcdef'' are the variables in the second block. The following variable lists denote the corresponding sets of variables.

Suppose that the variables in the current ring, in the order they were given in the ring command, are ``xyzdcbax[1]x[2]x[3]y[2]''. Suppose that ``xyz'' are the variables in the first block, and that the rest of the variables are in the second block. The following variable lists denote the corresponding sets of variables.