Evaluate(t)

Evaluate expects a text value t, and evaluates it as though it were an expression in a definition. It returns the value resulting from evaluating the expression. For example:

Evaluate('10M /10') → 1M

If t contains any syntax errors, Evaluate returns Null; it will not flag a syntax error.

One use for Evaluate is to convert (coerce) a text representation of a number into the number itself, for example:

Evaluate('100M') → 100M

Like most other functions, it returns the deterministic (Mid) or probabilistic value, according to the context in which it is called. Evaluate is powerful, and useful for a variety of purposes, but, it has some subtle aspects. Consider:

Variable A := 99
Variable B := (VAR A := 0; Evaluate('A + 1'))
B → 100

The Variable A in the evaluated text 'A + 1' refers to the global A, not the local A defined in B. More generally:

Evaluate(t) creates its own context for parsing t (at

evaluation time), which is quite separate from the context of the expression in which the Evaluate(t) appears.e.g., the definition of B above.

So, text t cannot refer to local Variables, indexes, or function

parameters defined in the context in which the Evaluate(t) function appears.

If the text value of t refers to any global Variables—e.g., A in

the definition of B above—these will not appear as Inputs of B, nor will any changes to A cause automatic re-evaluation of B.

Text t may itself define local Variables and indexes, and refer

to them, but these will not be available outside t.

When Evaluate references another variable, Analytica will

not be able to track the dependency. For example:

B := A+1
C := Evaluate('A+1')

When A changes, Analytica will automatically ensure that B is updated, but it has no way of knowing C should also be recomputed.

Text t may itself be an expression that creates a text value to be evaluated by Evaluate. This text expression appears in the definition of V and is not subject to the above limitations, so, for example:

Variable V :=(Var x:= ’10’; Evaluate(x & x))
V → 1010