Calculations Settings

The Calculations page of BlockSim's Application Setup contains default settings that will be applied to calculated results when you create a new diagram or analysis in BlockSim. Note that some of the configurable settings that are saved with the diagram/analysis can still be modified from the control panel and others can now be modified via the Item Properties window.

• Precision to be Displayed on Calculations sets the math precision (number of decimal places) and the point at which the software will switch to scientific notation. For example, if the scientific notation tolerance is set to 5, then any number that is larger than 105 will be displayed using scientific notation.
• Precision for Convergence Criteria sets the tolerance that will be used as the convergence limit (degree of accuracy) for mathematical iterations (e.g., a value of 4 indicates 1E-4 tolerance).
• Fault Tree Tracer Options sets the maximum number of blocks to read and maximum percentage of memory to be consumed by the fault tree tracer utility. The trace will terminate when any of the specified maximum values are exceeded. Setting lower values can help prevent out-of-memory issues. The memory threshold must be a value between 0 and 1, where 1 indicates no limit).
• Other Options
  • Use identical block simplification by default for new diagrams. Select this check box to use identical block simplification (IBS) for analytical RBDs and for analytical fault trees using the Equation analysis type. When IBS is used, the software looks for identical blocks (blocks with the same failure characteristics) in a parallel configuration and attempts to simplify the system equation, if possible, when analyzing the diagram. This is useful when analyzing large diagrams that contain a lot of the same blocks. You can also select to use IBS from the analysis settings page for analytical diagrams. In addition, the Diagram > Selection > Diagram Actions > Change IBS Setting command opens the Change IBS Setting window, which offers you the option to simultaneously apply the same setting to the current diagram and all of its subdiagrams, and their subdiagrams, etc.
  • Use mean time for the exponential distribution. By default, lambda is used as the scale parameter of the exponential distribution. Select the check box if you prefer to use MTTF (1/lambda) instead.
  • Fault tree analysis type controls the analysis type used by default for new analytical fault trees.
  • Equation is the original engine that has been used by all versions of BlockSim; it generates a reliability equation to calculate results.
  • Binary Decision Diagram (BDD) is a newer analysis engine that generates a binary decision diagram from the fault tree to calculate results. This newer engine can handle scenarios that the equation method cannot, and generally has better performance than the equation type.
  • Approximation BDD is a variant added in Version 2023 that generates a truncated binary decision diagram. This analysis type can handle extreme scenarios that even the regular BDD algorithm cannot. However, this variant is not capable of rendering plots other than the Static Reliability Importance plot.

For more detailed information about the analysis types, see Fault Tree Analysis Types.