On 16 Jan 2010, at 01:40, Michael Chen wrote:
The input I have is linear equation like:
2 * x + ( x - y ) = x + 1
And I would like to get at end
2 * x - y = 1
I studied the calculator example, and be able to build ast tree.
however I have no way to reduce it. Please give me an example or
link. Thanks.
You need methods used in symbolic programming (like Maple), theorem
provers, and CLP like:
http://en.wikipedia.org/wiki/CLP(R)
http://en.wikipedia.org/wiki/Constraint_logic_programming
One can solve polynomial equations using Buchberger's Groebner Basis
Algorithm. Given an ideal (p_1, ..., p_k) it produces a new set of
generators relative a monomial order on diagonalized form. In the case
of one variable, it reduces to the Euclidean algorithm computing the
greatest common denominator. For a set of equations, just write them
as p_1 = 0, ..., p_k = 0, and apply it to the ideal (p_1, ..., p_k).
If you want to just solve linear equations, you can use just the
ordinary matrix solution method: write matrices A X = B, and solve it.
- Check for computationally efficient methods doing this.
When doing it the CLP way, one integrates this algorithm into the
unification process that i Prolog is used to unify the heads of the
clauses. This produces a very elegant way to solve them, as you can
see on that link above, but is somewhat limited if one wants to do
more general things.
Hans
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