Re: Algorithm to solve equation for variable
 

Dan wrote:
> I am looking for an algorithm to solve an equation for any particular
> variable. For example, if I have the equation y = w * h + l (actually
> I have y = w h * l + because I'm using postfix notation), I need an
> algorithm that can solve the equation for any of w, h, l.
>
> I only support the four basic operators in my equations ( + - * / )
> and do not support functions. The way I store the equation is in a
> container; each item in the container is either a variable name or an
> Integer representing the operation, where + is 2, - is 3, * is 4 and /
> is 5.

If you have this equation
0 = x*x*x*x*x + b*x*x*x*x + c*x*x*x + d*x*x + e*x + f
and are asked to solve for x, there is no analytic solution. Equations
of order 5 or higher have no general solution. I believe that what your
asking to do is *very* difficult in general. Mathematica is big,
expensive piece of software that does some of this (and a lot of other
things).