Hi - I added a moving average trend line (actually, it is a curve) to a histogram scatter chart. As the x-values increase, the y-values start at 0, increase to a maximum value, and then return to 0. From this trend line, I would like to extrapolate the two X values for a given Y value (that is, the x-values for the ascending and descending portions of the curve for a given y value). Is there a way to get XCEL to calculate this? Thanks, Loren