PREVAL returns a previous case value

Syntax

PREVAL(Case_Pa, NumExp)

Arguments 

  • Case_Par is the parameter from which a previous case value is requested
  • NumExp is a numeric expression is the number of cases back from which the value is to be taken.

Remarks

  1. PREVAL is an essential function to describe processes on a time axis in the form of differential schemes.
  2. If the indicated case number is less than 1, the value of case 1 is taken. In case a previous value is not available, the Modeller will go back to that case and will attempt to derive the value by placing it in the goal list. Under normal circumstances this will be a PENDING starting value. 
  3. Important: Case_Par should be a parameter and no value or any other numeric expression.

Examples


Let the current case number be 9, then

PREVAL(4,3)

will return the value for A in case number 6 (9-3=6)

 

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