## Constants

Constants are fixed values that represent model inputs, fixed constants, or any other value that does not change. Constants are not modified by the solver as it searches for a solution. As such, constants do not contribute to the number of degrees of freedom (DOF).

Constants are declared in the *Constants ... End Constants* section of the model file. The constants may be defined in one section or in multiple declarations throughout the model. Constant initialization is performed sequentially, from top to bottom. If a constant does not have an initial value given, a default value of 1.0 is assigned. Constants may also be a function of other constants. These initial conditions are processed once as the first step after the model parsing.

### Example

! Example model that demonstrates constant declarations Model example Constants c0 ! no initial value provided - default = 1 c1 = 1.5 ! initializes to 1.5 c2 = 2 * c1 ! initializes to 3.0 c3 = exp(c2) * c1 ! initializes to exp(3.0) * 1.5 my_constant = 5 ! initializes to 5.0 End Constants Variables x[1:c2] = my_constant ! create a vector of 3 initialized to 5 End Variables Equations x[1:c2-1] = c3 x[c2] = c1 + c2 + x[1] End Equations End Model |