Use the Auxiliary Dependent Variable node to solve additional first-order ordinary differential equations for each ray released.
Enter a Field variable name. The default is
rp and can be changed to anything provided it does not conflict with the name of the variables for the position or momentum degrees of freedom, or with other auxiliary dependent variables.
Enter a Source R. The unit of the source depends on the unit of the auxiliary dependent variable and the option selected from the
Integrate list described below.
Select a way to Integrate the equation you have defined:
With respect to time or
Along ray trajectory. For example, to reproduce the variable for optical path length, you could set the
Source to
1 and set
Integrate to
Along ray trajectory. To compute the length of the ray trajectory you can set the
Source to 1 and set
Integrate to
Along ray trajectories.