Solve Many equations

I know numerical methods can solve problem but I think I dont need to define these methods and excel can do this

Solver/Goal Seek is how Excel implements (at least pre-programmed for us) numerical method.

One possible approach might be to treat it like a "curve fitting" or "regression" type problem:

1) Where you have "unkown", enter an initial guess for each x.
2) Add a column where you calculate y using your equation for each of those X's
3) Add a cell (or group of cells, depending on your style) that will calculate the "error" in the "regression" (=sumxmy2() is a good function for this http://office.microsoft.com/en-us/ex...in=HA102752955).
4) Call Solver and tell it to set target cell with your "error" term to a minimum by changing your X values.
5) Evaluate the result to see if Solver converged on a suitable solution.

Originally Posted by p30tec

Yes , I know but this approach is good for few unknown if I want to do this 5 step for all 100 cell's this approach is Boring
I need a way to extend this approach , but I dont know how ? because I cannot drag&drop to extend or use Array in Goal Seek

I am sorry if you find this approach boring. What kind of approach would you like that would be less boring? According to Frontline and Microsoft, Solver should be able to handle up to 200 "by changing" cells. Properly structured, it seems possible to structure a single Solver model to solve, in one step, for all 100 unkowns.

I have frequently written my own NR (or other root finding algorithm) directly into the spreadsheet. This can be fun, though it would be significanlty more work -- especially if this will be your first attempt at writing a spreadsheet with intentional circular references and iteration enabled.

Sometimes, I find it easier to write these kind of iterative algorithms into a programming language like VBA. Code the root finding algorithm into a user-defined function, then call the function from the spreadsheet. Would you be interested in this kind of approach?

While I personally generally find it easier to code my own NR type algorithm, some users here prefer to write a loop in VBA that will call Solver for each row and solve each row separately.

There are several different approaches we can use for a problem like this, let us know how you want to approach it, and we should be able to help you with programming that approach into Excel.