Hi Mack, slope is calculated at the very end, so what happens, is we sum up
value * duration until a bin is full taking the number of 'unknown' seconds into account and finally we divide the sum by the number of known seconds ... if you have a good test for this, please feel free to add this to the rrdtool wicki on the rrdtool website. cheers tobi Yesterday [email protected] wrote: > I am looking for a description of the actual interpolation method used to > convert data points to RRAs in the specific case of 1:1 correspondence. > > Rate generation data: > > > 920805000:10 > 920805300:20 > 920805600:10 > 920805900:10 > > Generated data: > > > > 920805000:000 > 920805300:3000 > 920805600:9000 > 920805900:12000 > > > Example data: > 920805000:000 > 920805305:3100 > 920805603:9030 > 920805907:12070 > > RRD results: > <!-- 1999-03-07 05:10:00 CST / 920805000 --> > <row><v> NaN </v></row> > <!-- 1999-03-07 05:15:00 CST / 920805300 --> <row><v> 1.0163934426e+01 > </v></row> > <!-- 1999-03-07 05:20:00 CST / 920805600 --> <row><v> 1.9737072285e+01 > </v></row> > <!-- 1999-03-07 05:25:00 CST / 920805900 --> <row><v> 1.0098993289e+01 > </v></row> > > The first data point is what would be expected. > ie. 3100/305.= 10.163934426 > > For the additional data point: > 5930/298 = 19.899328859 > > Then it look like we first interpolate the data point for > 92805300 = 3049.1803279 > > That gives > 5980.8197213/303=19.738678948 > Which is close but still differs in the 5th decimal place. > > If we do a full second degree interpolation: > 92805300 = 3049.1803279 > > 92805600 = 19.899328859*295+3100 = 8970.302013405 > > So > 8970.302013405-3049.1803279=5921.1216855 > 5921.1216855/300 = 19.737072285 > > This seems to be what is done but I have not seen a description anywhere. > Is this indeed what is done? > First interpolating the data points and then calculating the slope? > The final data point below seems to confirm this. > Could this be added to the FAQ or the documentation some where? > > Mack > > Ammendum: > For the final data point. > 3040/304=10 > > 92805900 = 10*297+9030 =12000 > 12000-8970.302013405=3029.697986595 > 3029.697986595/300=10.098993289 > > **************A Good Credit Score is 700 or Above. See yours in just 2 easy > steps! > (http://pr.atwola.com/promoclk/100126575x1221421323x1201417385/aol?redir=http:%2F%2Fwww.freecreditreport.com%2Fpm%2Fdefault.aspx%3Fsc%3D668072%26 > hmpgID%3D62%26bcd%3DAprilfooterNO62) > -- Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland http://it.oetiker.ch [email protected] ++41 62 775 9902 / sb: -9900 _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
