Discrete Variables with State Values
From Netica
Discrete Variables with State Values
When a node equation contains a = 4 && typeof(BSPSPopupOnMouseOver) == 'function') BSPSPopupOnMouseOver(event);" class="BSSCPopup" onclick="BSSCPopup('X_PU_discrete.htm');return false;">discrete variable which has = 4 && typeof(BSPSPopupOnMouseOver) == 'function') BSPSPopupOnMouseOver(event);" class="BSSCPopup" onclick="BSSCPopup('X_PU_state_value.htm');return false;">state values defined, the numeric quantities which that variable supplies to the equation could be the state indexes of the variable, or the values associated with the state indexes. Usually a function or operator will assume it is the values that are desired, but in a few cases it will use the state indexes, for instance if the other arguments to it are state indexes.
For example, consider the equality operator, and a discrete variable Color, which has values and state names (such as blue) defined. When Color appears in the equation, it could refer to a state index of Color, or to the value associated with that state index.
Uses state index: Color == blue Color == #1 #Color1 == #Color2
Uses state value: Color == 3.2 Color == 1 Color1 == Color2
The above is for the evaluation of equation expressions. When it comes to assigning the result of the equation to its LHS (left-hand side) variable, if the variable is discrete with values defined, the same issue arises. Has the equation calculated a state index for the variable, or a value associated with the state? The purpose of the AsState function is to indicate that state indexes should be used.
Continuing with the example above:
Assigns by value: Color() = 3 Color1 (Color2) = Color2
Assigns by index: Color() = #3 Color1 (Color2) = AsState (Color2)
Color1 (X, Y) = AsState (integer (X / Y))
You may want to verify that Netica is doing as you expect by having it calculate a few values and checking (for example, by using Table → Equation to Table). Or you can examine the internal representation of the equation by choosing Report → Horizontal Format from the menu and then Report → Equation. Check for places where Netica has inserted the function "_levels" (maps state index → real value), "_find0" (maps real value → state index of a discrete variable), or "_discretize" (maps real value → state index of a continuous variable).