*From*: Rune Svendsen <runesvend gmail com>*To*: gnumeric-list gnome org*Subject*: TREND and LINEST give different results when applied to the same data*Date*: Tue, 08 Jun 2010 09:59:46 +0200

Hi I have some data, a set of X- and Y-values, for which I'm trying to calculate a future Y-value. So far it's going good. It seems the FORECAST and TREND functions do what I want, which is take all the data into account, and calculate the future value based on what best fits all my data points. FORECAST and TREND produce the same result when I use it on my data. I have read that TREND basically uses LINEST to calculate its future value, and as far as I can see, FORECAST is the same as TREND except that it only calculates a single future value, compared to TREND's ability to calculate multiple future values. Now the thing that I find strange is the following. When I apply LINEST to my data, and thus obtain the slope of the regression line, and the y-intercept of the line, and use *these* numbers to calculate my desired future value (which should be how TREND does it, right?), I get a different future result than I get when I use TREND. The future values I obtain from TREND and from using the output of LINEST are the following, respectively: 40407.91963867 and 40407.94565792. Since this number represents a point in time, the difference amounts to 37 minutes and 28 seconds, which I think is quite a bit. Can anyone explain why I'm seeing this discrepancy? Thanks! /Rune

**Follow-Ups**:**Re: TREND and LINEST give different results when applied to the same data***From:*Morten Welinder

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