Well I'm still working on that universal equation thing. I have a series of equations, all related - like a series of steps to take - one follows the other. I calculate the value of a variable, r, based on x. If r is equal to 1, then I finish up the calculation because I know everything is set up right. If not, then I want to increase d by 1, and then repeat the calculation. Is there a standard mathematical way of expressing this?

And one more question: In multivariable-differential calculus, if your calculating dy/dx as x->0, couldn't you just add one to the exponent of each x in the equation of change in y/change in x? It seems to work and is a lot simpler than waht my book says.