Polite question and suggestion about "solve".

[John P]

Hello,

I am asking for this becouse I want to store some function for ex. "xt-xo*(1+r/100)^t" in a variable say "ExpGrowth", then if I want to slove it for say "xo" and not to get this 'message' of missing "=0" when using "solve(ExpGrowth,xo) I have to store it as: "xt-xo*(1+r/100)^t=0" and it solves correvtly. If I want to for example differentiate it wrt. some variable I get the derivative "=0" and that does not work if I want to evaluate the derivative numerically. However, there is a way around the problem by using"left" diff(left(ExpGrowth,r)) and it works OK, but I think adding "=0" to an expression, not equation, and remembering adding "left" is unnecessary complication and sort of nuisance.

Cheers