Rate of Change

Rate of Change

The formula ROFC(x) allows you to calculate the per second Rate of Change from one data point to the next, where x = the number of points. For example, the formula ROFCA(3) will calculate the per second rate of change for variable A --over the previous-- back three (3) points. Multiplying the output by number of seconds allows you to calculate the rate of change over longer time intervals. For example, the formula ROFCA(3)*3600 calculates the hourly rate of change for variable A over the previous three (3) points. This calculation is extremely useful for calculating the rate of change in river height as it occurs.

 

Create a Rate of Change Calculation

  1. Ensure the variables Depth and Rate of Change are visible in the datasheet.
  2. Right-click in the datasheet area and select Calculation.
  3. Select Depth as Master Variable A.
  4. Enter the formula:  IF(ROFCA(3)*3600>0.1,IF(ROFCA(3)*3600>2*ROFCA(6)*3600,20,15),20)
  5. Select the output variable Rate of Change.
  6. Select the Calculation Chart tab, where you can review the calculation input variables and the result of the proposed calculation.
  7. Similarly, select the Calculation Result tab to review the data in grid view, before completing the calculation.
  8. Check the Database box in the output section.
  9. Click Update. Enter comments about your processing, if any. Then click OK.
  10. Once you have completed the calculation you can Save the Calculation Template (from the Quick Access Toolbar) if you wish to use this specific calculation again. The Calculation can be named.

The Calculation can be scheduled to run on a routine basis using Tasks.

 

See also:

  • Automate Your Tasks
  • Calculation Templates

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