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Residual constraints are used to constrain the amount of any particular product remaining to be cut in any given period. This constraint is useful if there are environmental factors or similar factors that need to be taken into consideration.
The residual constraint window used in LOG 2.0 is shown below.
This option specifies what periods the constraint is to apply. Checking the box All will mean that the constraint will apply for all periods. Alternatively, a period range can be entered by entering the first and last periods in the two boxes below.
Rather than repeatedly specifying the same constraint for different croptypes or age classes, the For Each option allows the same constraint be applied to every individual croptype or class of croptypes selected in the Croptype Range.
This option means that a single constraint will be applied to the model that encompasses all the croptypes or classes of croptypes specified in the Croptype Range in the constraint.
Depending on what is selected in the Category field, a range of croptypes or attribute names will be available in the Croptype Range list. Using the mouse, highlight the desired croptype ranges for which the current specification is to apply. To select consecutive items in the list, click the first item, press and hold down the [SHIFT] key and click the last item. To select non-consecutive items, press and hold [CTRL] and click each item.
The age range defines the range of age classes for which the particular constraint will apply.
To specify all age classes, simply ensure that the All Ages box is checked. Note that LOG will check this box automatically.
To specify a range of age classes, ensure that the All Ages box is not checked and enter the first and last age classes in the boxes provided below.
Selects whether the residual constraint applies to yield, area, revenue or costs.
States whether the constraint is equal to "=", less than "<" or greater than ">" a specified value.
This is the value that the constraint will be constrained too. For example, the Residual constraint shown above restricts the area remaining has to be greater than 50,000 hectares.
The latest version of LOG now includes error checks on all inputs. This means that all fields need to have appropriate entries before the addition to the model is added. If there is something missing, or something in the wrong form, then a message is shown that prompts the user to remedy the situation.
Other Changes to the LOG 2.0 Residual Constraint Window*
The old version of LOG did not model the residual constraints correctly. This was due to problems in the LP model. These problems have since been found. LOG 2.0 now gives the same answers to problems with residual constraints included as FOLPI does.