Origin Ver. and Service Release (Select Help-->About Origin): 8.6 Operating System: Win 7
I did a 9th order polynomial fit and Origin did output the fitting parameters B1-B9. The fit worked well, the values calculated by Origin are very close to the original values.
However, when I use the parameters in Excel the calculated values differ significantly from those in Origin. It's not a problem in Excel, I used a pocket calculator and got the same wrong results.
For x = 10.04374 Origin gets 27.2526715364701, but I get 27.20678141 (using Intercept + B1*x^1 + B2*x^2 and so on).
I guess the Bx values in the report table are not the values actually used by Origin, but rounded ones. Is that so and how can I access the exact values Origin used? I need these for some calculation in Excel.
High order polynomials vary significantly with only minor changes to significant digits of input values...
Click the drop-down button next to Parameters on your Report sheet and choose "Create Copy as New Sheet". Double click the top of the Value column to open Column Properties. Set Digits to "Significant Digits=" and enter 15 for Significant Digits and click OK.
Getting exact values of polynomial fit
Posted - 10/18/2013 : 06:42:17 AM
