Constants

A constant is a numerical quantity whose value does not vary during the lifetime of any instance (Element) of the model in which it is declared or defined.

Defined Constants

A defined constant is a constant local to the model which is defined in its Constants area and whose value is that of a local expression to the model.

<Constant> ::=
      <name> : <quantity> = <value>  <ConstantOption> ;
     |
     <name> : <quantity> in [ <vmin> , <vmax> ]  = <value> <ConstantOption>  ;
     |
     <name> : <quantity> in { <v1>, …, <vn> } = <value> <ConstantOption>  ;
     |
     <name> : <quantity> = <constant expression> <ConstantOption>  ;
     |
     <name> : <quantity> in [ <cexprmin> , <cexprmax> ] = <constant expression> <ConstantOption> ;
     |
      <name> : <quantity> in { <v1>, …, <vn> } = <constant expression > <ConstantOption>  ;

with

<ConstantOption> ::=
        |
        default
        |
        redefine

Note

Some universal constants are predefined in DEPS. Thus Pi represents the predefined constant whose value is that of the transcendental number π.

Declared constants

A declared constant is a constant local to the model which is defined in its Constants area and whose value is that of an expression passed as an argument of the model.

<Constant> ::=
     <name> : <quantity> ;
     |
     <name> : <quantity> in [ <vmin> , <vmax> ] ;
     |
     <name> : <quantity> in { <v1>, …, <vn> } ;
     |
     <name> : <quantity> in [ <cexprmin> , <cexprmax> ] ;
     |
     <name> : <quantity> in { <v1>, …, <vn> } ;

Examples

The following peace of Model shows an example of the constant’s zone of a Model:

Constants
a : Real = 3.5 ;
b : Real in [0,  , 20 ] = a^3 ;
c : Real in { -10.2, 0.0, 1.5, 2.3} = 1.5 ;
d : Real = a/b+ln(c) ;
e : Real in [ 2*a , 2*a+5 ] = 2*a+3 ;
f : Real in { a+2, a+4 , a+6} = a+4;

We can see that constants may depend on other previously defined constants both for the definition domain and for the value.