DIFFERENCE

   LET @schedule = @schedule1 - @schedule2

   LET @schedule = @schedule1 MINUS @schedul2

Description

The difference of two schedules is analogous to the difference of two sets: the resulting schedule contains every point that is contained in the first schedule but is not an interior point of the second. Differences are useful for determining intervals during which one set of constraints is met while another is not.

A graphical description of the DIFFERENCE command is shown below.

   operand schedule1      -------  ---------   ---------       -
   operand schedule2   -----    --       ----------         ------
   resulting schedule       ----   ------          -----

Examples

In the following example, a schedule containing intervals when two satellites are close together is differenced with a schedule containing intervals when the apparent angular rate between the satellites is near a maximum. The resulting schedule contains intervals when the satellites can be observed together with low smearing.

   IMPORT IO_EUROPA_CLOSE.WIN     AS TOGETHER;
   IMPORT IO_EUROPA_MAX_RATE.WIN  AS FAST;
 
   LET LOW_SMEAR = TOGETHER - FAST;
 
   EXPORT   LOW_SMEAR TO IO_EUROPA_LOW_SMEAR.WIN;

Related Topics

1. Complement
   
2. Intersect
   
3. About Schedules
   
4. The Percy Help System