https://www.mathworks.com/help/nav/ref/estimategravityrotation.html
This MATLAB function estimates the gravity rotation, using factor graph optimization, that helps transform the input poses to the local navigation reference...
factor graphestimategravityrotationusing
https://www.mathworks.com/help/nav/ref/factorgraph.addfactor.html
The addFactor function adds one or more factors to a factor graph and can group the factors and nodes that are specified by the added factors.
addfactorgraphmatlab