Apache OpenOffice (AOO) Bugzilla – Issue 84623
regression function displayed is inconsisent
Last modified: 2013-02-24 21:19:01 UTC
In OOo 680m238 (pre-2.4.0) I display the regression function for an exponential curve (recently implemented in issue 7998). OpenOffice.org's displayed function neither fits the data nor the plotted line on the chart. (The line on the chart looks fine.) OOo gives the function f(x)=26.45*1.03^x while Excel 2003 gives y=26.445*e^(0.0252*x).
Created attachment 50363 [details] source file from OOo 680m238 (pre-2.4.0)
I see no problem. Please consider this: (1) Excel uses three decimals and OOo two. Therefore the numbers are rounded different. You can set in the object properties of the equation how many decimals OOo should show. (2) You can not expect to be accurate if you use values which are rounded. (3) In most cases the regression line will not fit the data exactly. That's a property of regression lines. (4) Remember the rule a^(b*c)=(a^b)^c. Here it gives you e^(0.0252*x)=(e^0.0252)^x=1.02552^x If you want, that OOo always uses the base e, then the spec has to be changed. The issue type would be a request for enhancement, not a defect.
@ aziem: as Regina has written pls write an enhancement. I will close this issue
Sorry and thanks. I was wrong. I do not care as much about the base as I do precision, so I filed issue 85005 asking for more precision (at least, by default).