Function Editing

Editing utility functions requires quite some skills and experience, particularly when the corresponding tables are large. You may want to try some of the following function editing approaches.

For small tables, which consist of about up to 10 or 20 rules, it is probably most effective just proceeding sequentially through the table and entering all the values in one turn. For fast data entry, use the keyboard keys 1, 2, etc., and Delete.

For tables of intermediate size, up to 50 or maybe 100, a useful approach is to combine your data entry with DEXi’s ‘Use scale orders’ strategy. In this case you ‘jump’ across the table and enter values only for some ‘important’ rules, such as rules having extreme values of attributes or extreme function values. [Indeed, it takes some practice to learn which rules are ‘important’.] At the same time, you let DEXi calculate values of non-entered rules. In this way, you may quickly get a highly determined function. You may follow this stage by several iterations of finding ‘weak’ (unsatisfactorily defined) points of your definition and entering your values there until the function has been completely defined.

For even larger tables, you should additionally employ DEXi’s ‘Use weights’ strategy. Start again with entering ‘important’ values. Then, open Weight Editor and define your required attribute weights. If successful, this will fill all the non-entered cells with single values corresponding as closely as possible to your weights and already entered rules. Afterwards, do not forget to check what DEXi has done automatically for you. Review the assigned values and verify if they make sense to you. Also check the actual weights achieved in this way (for example, run Weight Editor again and see the ‘Current’ weights).

Although DEXi can work with less-than-completely defined utility functions, it is highly recommended to define the functions completely. Incompletely defined functions may cause options to be evaluated by sets of values rather than single values. Therefore, you should check the status of your functions and ensure that they are ‘100% determined’.

As long as your function is ‘100% determined’, the proportion of actually entered rules is not that important and can be less than 100%. However, even in this case you should be aware that non-entered rules are more volatile than entered ones. Entered values are never changed by DEXi, but non-entered values may be unintentionally changed later, for example, by changing weights in Weight Editor. To protect your completed function from such changes, you may want to run the Enter values command.

For final verification of your function, you may also want to review its complex rules and weights.