Polynomials of several variables: %%%{ %%%}

### 6.27.2 Polynomials of several variables: %%%{ %%%}

A polynomial of several variables can be represented in different ways:

- by a symbolic expression.
- by a dense recursive 1-d representation like above.
- by a sum of monomials with non-zero coefficients (distributed sparse representation).
  A monomial with several variables is represented by a coefficient and a list of integers (interpreted as powers of a variable list). The delimiters for monomials are %%%{ and %%%}.
  For example 3x2y is represented by %%%{3,[2,1]%%%} with respect to the variable list [x,y]), and 2x3y2z − 5 xz is represented by %%%{2,[3,2,1]%%%} - %%%{5,[1,0,1]%%%} with respect to the variable list [x,y,z].
  For a sparse representation, a single variable polynomial can be regarded as a multivariate polynomial with one variable.