definition - equation and variables

Hi,

I am have used STAN to create some basic models of waste flows and stocks in Bangalore. I would like to know the definition of the equations and variables and how these are calculated. I created a very basic model with 1 input flow, 1 export flow and 1 process with stock. When I pressed the calculation button it said “The math model comprises 5 equations and 8 variables”. What are these 5 equations and 8 variables how are they related to the flows and stocks in my model.

Thank you for answering my basic question.

Best,
Megha

Your model can be described by 1 equation (mass balance of your process) and 4 variables (import flow, export flow, stock, change in stock). Additionally, STAN always sets up 4 equations to compute 4 system related variables: sum of imports, sum of exports, sum of stocks and sum of change in stocks. So, in total you get here 5 equations and 8 variables.

Thank you so much for your reply.

I've used STAN for some analyses. In the paper describing these analyses is it ok for me to say "STAN models consist of flows and stock described by equations (mass balances of the processes, sum of imports, sum of exports, sum of stocks and sum of change in stocks) and variables (import flows, export flows, stocks, change in stocks, sum of imports, sum of exports, sum of stocks and sum of change in stocks). The number of equations and variables in a model depends on the number of processes and flows (import and export)."

Thank you again for your advice.

Wish you a good day.

Best,
Megha