Generating Table & Chart from Sheet with complex data

Greetings,

I was wondering if someone may know whether a function exists in Excel to generate a chart (or table first) from the formulas in a sheet, which will "plug in" values for a given input box and give outputs in a specified range (like x=1 through 1000) and give the corresponding y values (4+ for each x).

The object is to avoid entering a new 'x' value over and over, pasting the results for 'y' from each one, and then having to redo it whenever one of the underlying variables changes.

There are plateaus in the underlying data that jump up every so often, and seeing these points it, well...the point...of making the chart, so I can't simplify it into an mx+b style formula.

Thanks!