Efficient usage of patterned data

 

Syntax

BD>factor : X=I ,I ,I

where X is the name of an element or data-carrier, and are positive integers.

The FACTOR:  command allows the construction of patterned data efficiently so that it occupies very little memory. X is the name of either of an element or data-element, or will be created as a new data-element. If data already exists for this named quantity, it is deleted. The effect of the command is to create observations for the cases , and for this range of cases, to define the observation for the case as

Thus the data vector consists of integers from , each integer being repeated consecutively I2 times in total; this process to continue until the specified length (I3) is reached. As an example, consider the following fragment of code:

BD>factor : X=3,2,7

This results in the creation or overwriting of a data-carrier X having the 7 observations:

Data created in this way uses no conventional data storage - it is evaluated and retained in functional form. However, if at any time data that was defined via a FACTOR:  command becomes partly or wholly redefined, the efficient definition of the factor is deleted, and it is as though an entirely new data element is being defined.