Polynomal trend line

[Not So Smart]

I have been creating scatter charts and then inserting Polynomal (6) trenlines. I can find the (Y) value on this chart visually with a ruler.

I would like to be able to use a user defined function (much like the "Forecast" function) to be able to get the exact (Y) value given an (x) value.

Does anyone know of a user function or other code to do this in Excel?

Thanks

David

[mdmackillop]

Hi David,
Can you post a sample workbook? It makes life much easier if we can see data and a layout. You can also clarify on the spreadsheet the relevant values.