We refer to key model variables which depend only on 1) the values of the control variables and 2) the input parameters as diagnostic variables. Examples are the CO_{2e} concentrations c_{M,R}(t), the temperature change T_{M,R,G,A}, and the cost of mitigation \mathcal{C}_{M} M^{2}.
In ClimateMARGO.jl, diagnostic variables are represented as julia functions, which are implemented using two separate methods, based on the type of the function arguments: the first method requires an explicit list of all the input parameters and control variables that determine the diagnostic variables; the second method leverages the ClimateModel struct to read in the required variables.
For example, here are the two methods that define the diagnostic function T for the temperature change:
CurrentModule = ClimateMARGO.Diagnostics
T