For any polynomial, we need to keep track of 'what variables it's a polynomial in'. This is accomplished by associating a variable list with the polynomial. This is a list of Ropes (the variables). In order for scanning to work, variables should be Cedar identifiers. A variable list should be written as comma-separated variables enclosed in parentheses (whitespace ok anywhere except within a variable). For example, "(x,y,z)".

Once a variable list is established, a polynomial is written as a sequence of terms in the variables of that list, terminated by a " $" (leave a blank before the $). Order of terms doesn't matter. Multiplication is implicit (whitespace between coefficients and variables). Exponentiation is indicated by either "^" or "**". Coefficients can be either rational numbers or integers. Order of occurrence of variables in a term doesn't matter (no duplicate monomials allowed, however). For example, with variable list "(x,y,z)", the following is a legal polynomial:

Error if a variable not in the variable list occurs, but not all variables in the list need occur in any given polynomial. Case matters in variables. Order of occurrence of variables in a term doesn't matter.

No algebra (i.e. no recursive structure) currently supported in input.

Run Algebraimpl.bcd, and you'll get an Algebra viewer. Select a variable list somewhere (other than the Algebra viewer, which is only for output), and click the VarList button. The variable list will be echoed back to you. Now you can input polynomials with this list. Select a polynomial somewhere, and click either Poly1 or Poly2 to set one of the two global operands. The results of arithmetic operations will be stored in Poly1.