# International Futures Help System

## Computations on the Fly

Computations "On The Fly" can be conducted from the Type Name Box located on Self-Managed Full Variable/Parameter selection screen.

**Basic arithmetic operations.** For instance, to compute ratios of two variables, type the name of a variable followed by a "/", e.g. GDP/ Then select one or more subdimensions as appropriate. Then type the denominator variable, e.g. POP, selecting appropriate subdimensions. In the status box you will see an indication (truncated) of your computational specification. When you exit to display and select a display form such as Table, you will obtain a display of GDP/POP. Be sure to specify GDP/ (or another variable for the numerator) for as many regions (or other subdimensions) as you wish before specifying POP (or other denominator variable) for the same number of regions (or other subdimensions). For instance, it is permissible to specify GDP/ for ALL regions, then POP for all regions, in order to see GDP per capita for all regions. Similarly, you can compute products of two variables. The process is the same as for ratios, except that you use the "*" operator. For additions use "+" and for subtractions use "-". In additional to specifying variable names, you can also put numbers into a computational sequence, for instance 1000 as the entry following GDP/ That allows you to scale a value.

**The percentage of one variable of another.** Select the "full set" of variables for display purposes and type the name of a variable followed by a "%", e.g. CS% Select one or more subdimensions as appropriate. Then type the denominator variable, e.g. C, selecting appropriate subdimensions. When you exit to display and select a display form such as Table, you will obtain a display of CS as a percent of C. Be sure to specify CS% (or another variable form the numerator) for as many regions (or other subdimensions) as you wish before specifying C (or other denominator variable) for the same number of regions (or other subdimensions). For instance, it is permissible to specify CS% of agriculture for ALL regions, then C for all regions, in order to see consumption of agriculture goods as a portion of total consumption for all regions.

**A sum across a dimension of a variable.** Precede the variable name by "WW" in order to activate the summing (think "world-wide" for WW). For instance, specifying variable name "WWPOP" will produce the sum of population across all regions. When you wish to produce a sum across one dimension of a two-dimensioned variable, specify "ALL" as the element for the dimension across which to sum.