› Forums › Spectroscopy › Help with ISIS › rms calc
15 January 2017 at 11:22 am
#577811
![](https://britastro.org/wp-content/uploads/2018/11/picture-219-1541235408-80x80.jpg)
Participant
Hi John,
To get the value for the rms residual given by ISIS you need to calculate sqrt(sumsq(dlambda values)/6) because you have 11 lines and there are 5 parameters in the fit.
David