The first model

A model consists of a file with a .txt suffix that contains a single model declaration. In the body of the model declaration you can load one or more modules.

In the beginning you can inline a module declaration into the body of your model. Later you will learn how to put modules in separate files so that they are reusable.

You must also declare at least one state variable for the model to compute. For this you need at least one compartment and one property to form the location of the state variable. Components are usually declared in the model scope, but properties can also be declared in the module scope.

We suggest you use MobiView2 to load and run your model.

We highly recommend to use a better editor than notepad to edit the text files, for instance use notepad++ or something else of your choice.

model("The first model") {
	
	# Declare the components
	soil : compartment("Soil")
	temp : property("Temperature")
	
	# This module declaration is inlined into the body of the model declaration.
	# Because of this identifiers in the model scope (soil, temp) are visible inside the module scope.
	module("A module", version(0, 0, 0)) {
		
		# Declare your first state variable. It has unit degrees Celsius.
		var(soil.temp, [deg_c], "Soil temperature") {
			20[deg_c]
		}
	}
}

To load this model you also need a data_set. This is put in a separate file with a .dat suffix. For now, it will only contain the start and end dates of the model run.

data_set {
	par_group("System") {
		par_datetime("Start date")
		[ 2000-01-01 ]

		par_datetime("End date")
		[ 2000-12-31 ]
	}
}

Of course, this model is not that interesting yet as the state variable doesn’t change over time.

Full code for chapter 01.