Error Propagation in Conditional Calculation Systems

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Solution Overview

Problem

Calculations that are based on alternative functions introduce errors due to measurement imprecision and rounding, and the uncertainty about which function to apply near the boundary between their domains can significantly impact the result, necessitating a method to account for these errors.

Innovation Solution

A system and method that calculate an error associated with a third calculation by considering the errors of the underlying functions and the probability of each function applying, using the formula √((μεa)^2 + ((1-μ)εb)^2 + μ(1-μ)(a-b)^2, where μ is the probability of applying the first function, εa and εb are the errors of the functions, and a and b are their respective results, to propagate this error to subsequent calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If alternative calculations are used to handle different circumstances, then adaptability is improved, but measurement precision deteriorates due to uncertainty about which function applies

Engineering Contradiction:
ImproveadaptabilityVSAvoidmeasurement precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The calculation system is segmented into multiple alternative calculation functions (ƒ(x), g(x), etc.), each applicable to specific circumstances or domains. This segmentation allows the system to adapt to different conditions while maintaining measurement precision by calculating error propagation for each segment and combining them using the square root of sum of squares formula, which accounts for the uncertainty in selecting the appropriate function.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If conditional boundaries are used to switch between calculations, then ease of operation is improved, but manufacturing precision deteriorates due to boundary uncertainty

Engineering Contradiction:
Improveease of operationVSAvoidmanufacturing precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The system applies beforehand cushioning by pre-calculating the error propagation formula that includes boundary uncertainty. Instead of dealing with boundary issues when they arise, the error formula is designed in advance to accommodate the uncertainty of which function applies, using probability-weighted error components that cushion the impact of boundary ambiguity on final precision.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If probability-based function selection is used, then reliability is improved, but device complexity increases due to error propagation calculations

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system changes parameters by introducing probability weights (μ and 1-μ) as new parameters in the error propagation formula. These probability parameters quantify the reliability of each alternative calculation path and are integrated into the error calculation, allowing the system to maintain reliability through probabilistic reasoning while managing complexity through a standardized mathematical framework.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS7979360B2Error propagation in calculation with conditional alternatives
Publication Date: 2011.07.12 ACCENTURE GLOBAL SERVICES LTD
  • US7979360B2 patent drawing
  • US7979360B2 patent drawing
  • US7979360B2 patent drawing

AI summary

The result of a first calculation may be determined by one of two alternative calculations. Each of the alternative calculations has an error associated therewith (due to factors such as measurement imprecision, rounding, etc.), and these errors propagate to the first calculation. However, there may also be error in the first calculation due to uncertainty about which of the alternative calculations applies. Such error can be taken into account based on the respective probabilities that the first and second calculations will apply, as well as the difference in the results produced by the two calculations.