From GeoGebra Manual
- SigmaXX[List of Numbers]
- Calculates the sum of squares of the given numbers.
- Example: In order to work out the variance of a list you may use SigmaXX[list]/Length[list] - Mean[list]^2.
- SigmaXX[List of Points]
- Calculates the sum of squares of the x-coordinates of the given points.