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RTAnalysisVariableManager / VariableOrderCalculation

Variable Order Calculation


When doing complex analysis it is important to understand the order of the calculations in the software.

  1. Data loaded
  2. Internally defined variables calculated in their native units (this includes Standard Variables, External Inputs, GPS Variables, Serial Variables)
  3. The units of all the internally defined variables are converted from their native units into the units required by the user
  4. The rate of change filter is applied to all variables
  5. The smoothing filter is applied to all variables
  6. The advanced filtering is applied to all variables
  7. The calculus functions are applied to all variables
  8. The variables are limited to the minimum and maximum values selected


Once this is completed...

  1. The user defined variables are calculated, starting at user variable 1
  2. For each user defined variable we apply the conversion of units, rate of change filter, smoothing, advanced filtering, calculus, min and max's
  3. Once each the processing for each user defined variable is complete we move onto the next


The order of the internal calculations define the way some operations are done, for example:

  1. The calculations of the user defined variables are based on the inputs after they have been converted to the users units, and after any filtering. So for example if analogue 1 is converted to a pressure, and analogue 2 is converted to another pressure by selecting the required sensor model, then to find the difference between the pressures using a user defined variable by simply using "VAR_29-VAR_30".
  2. The filtering is done before the user defined calculations are done, so in the case above if analogue 1 and 2 are filtered, then you would not have to filter the user defined variable to get a smoothed result.
  3. The calculus functions are carried out after any filtering or smoothing, this is important since typically you have to smooth a variable before you differentiate it to get a useful result.
  4. The calculus function is carried out after the variables are set to the users selection, so the differentiate and integrate by distance calculation will be affected by the users selection of distance units.
  5. The rate of change filter is the first filter to be applied, so any obvious spike are removed before any filtering is applied.
  6. With the User Defined Variables, you can only call other User Defined Variables sequentially. i.e. User Defined Variable 5 can call User Defined Variable 4, but User Defined Variable 4 can not call User Defined Variable 5, as User Defined Variable 5 hasn't been calculated, and will just return a null value.
Page last modified on August 28, 2012, at 07:57 AM