# Numerical equations with EMS

Hello,

I am trying to write a subroutine that calculates the temperature of my storage medium at each timestep. I am trying to apply a finite difference model that solves N ODEs for each node, the model is very similar to that of WaterHeater:Stratified where the temperature update equation for each node is:

Tfinal= (Tinitial +b/a).exp(a.deltaT)-b/a

Does EMS allow this sort of formulations ?

My idea is to create a trend variable for the temperature at each node, but I don`t understand how initialization works in EMS Any insights? Thank you