Error Messages/40730

Example error messages

Local variable K is not a valid index in the Local x[K] := ... construct.

Variable Revenue is not a valid index in the Local x[Revenue] := ... construct.

Description

The declaration of a local value specifies one or more allowed indexes for the local. The specified "index" isn't actually an index.

Suppose, for example, that Revenue is $1M -- which of course is not an index. Then you might see this error message in a declaration

Local cash_flow[Revenue] := ....

Maybe the author's intent was

Local cash_flow[Time] := ...

The error also appears with the following easy-to-make mistake:

LocalAlias K := Last_years_products_Idx;

Local x[ K,J ] :=....

The error occurs on the second line, but the mistake is on the first line. The intent here is for K to serve as an alias for a longer index identifier, but because the right-hand side of an assignment (:=) is evaluated, you would need to write

LocalAlias K := Handle(Last_years_products_Idx);

Local x[ K,J ] :=....

Without the Handle call, K ends up aliasing the value of Last_years_products_Idx instead of the object itself. If its value were a handle to and index, that would be fine. But when its value is just a list, that is not an index.