# Hiding Extension Variables

Some extensions have many variables, only some of which are of interest to the user. Hiding those that aren't of interest simplifies the display.

## Hiding Intermediate Variables

Some variables are used for intermediate calculations. For example, roof calculations might use the roof angle (calculated from the run and rise) in several places. But the estimator doesn't care what the angle is.

To hide an intermediate variable, simply check the box in the "Hide" column of the Standard Extension Edit Window.

## Conditionally Hiding Variables

Some calculated variables should be hidden if they have a zero value. To do this, check the "Hide if Zero" checkbox in the Extension Variable Properties Window.

Consider this formula to calculate the area of a wall:

**WallArea = Length * WallHeight - DoorCount * DoorArea**

For walls that have no doors, we don't want to have to enter (or see)
DoorArea. So we want to hide DoorArea if DoorCount is zero.

Prior to version 5.5 of Dimension, this had to be done manually. For input variables, the Extension Variable Properties Window has a check box "Hide if Variable is Zero". This drop-down list contains a list of the previous variables in the extension (plus a blank entry). If you select a previous variable and the variable is zero, unchecked or blank, this input variable will not appear in the drop-down or control panel quantity lists.

With version 5.5 of Dimension, a new option was added to "automatically" hide variables that aren't needed. The Extension Variable Properties Window has a check box "Hide if Not Used". If this is checked, Dimension analyzes the formulas and the existing values to determine which variables are used later in the extension. If a variable isn't used and "Hide if Not Used" is checked, the variable will be hidden. In our example above, DoorArea would have "Hide if Not Used" checked.

## Used and Unused Variables

There are a number of ways a variable can be unused.

**Note:** The information below assumes you are familiar
with Dimension formulas.

- When two numbers are multiplied, if the first number is zero, the second number is unused. So for TotalDoorArea=DoorCount*DoorArea, if DoorCount is zero, DoorArea isn't used.
- When one number is divided by another number, it the numerator (the first number) is zero, the divisor (the second number) is not used. So for TileCount=FloorArea/AreaPerTile, if floor area is zero, AreaPerTile is not used.
- When the IF function is used, if the condition (the first argument) is true, the second argument is used but not the third. If the condition is false, the second argument is NOT used but the third is. So for RebarLength=IF(RebarUsed, Area/RebarSpacing, 0) If RebarUsed is false, Area and RebarSpacing would not be used.
- When the OR function is used, if one argument is true, the remaining arguments are not used. So for RebarUsed=OR(Area>100,SlabDepthIn>8), If Area is greater than 100, SlabDepthIn is not used.
- When the AND function is used, if one argument is false, the remaining arguments are not used. So for RebarUsed=AND(Area>100,SlabDepthIn>8), If Area is less than 100, SlabDepthIn is not used.