I have a spreadsheet with a number of graphs on, and I have displayed the trend-lines / regression lines on these graphs. These are not simple linear regression lines, but are high order polynomial ones.

Is there any way that I can use the equations of these regression lines in my formulae, without hand-coding all the co-efficients? The equations are constantly changing, and I don't want to have to rewrite all my formulae every time I update the chart.

EDIT: The co-efficients vary because I am still adding data, and the regression lines are becoming more accurate as I add more data. There won't be a limit on the data - it will keep coming in, which is why I don't want to have to rewrite all the formulae each time.