Piecewise Linear Approximation Coefficient Selection

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Solution Overview

Problem

Existing computing devices face inefficiencies in approximating functions like inverse functions, square root functions, and trigonometric functions due to the high computational resources required for Taylor expansions, which consume significant processing cycles and memory.

Innovation Solution

A processor-based system that uses piecewise linear approximation by selecting and determining a set of piecewise analysis coefficients for a vector of input values, allowing for the estimation of function output values using a reduced number of instructions and memory, through a permutation network and arithmetic logic circuitry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Taylor expansions are used to approximate functions, then computational accuracy is improved, but computational resources and processing cycles are significantly consumed

Engineering Contradiction:
Improvecomputational accuracyVSAvoidcomputational efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent divides the function approximation into multiple segments or pieces, where each segment uses a simple linear model. Instead of using a complex Taylor expansion across the entire domain, the function is segmented into multiple intervals, each approximated by a linear equation with pre-calculated coefficients. This segmentation reduces the computational complexity from high-order polynomial calculations to simple linear operations while maintaining overall accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameters of the approximation method by switching from Taylor expansion parameters (derivatives, higher-order terms) to piecewise linear parameters (segment boundaries, linear coefficients). By pre-calculating and storing these linear coefficients for each segment, the system transforms a computationally intensive continuous approximation into a efficient discrete lookup and evaluation process, significantly reducing processing requirements.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple order polynomials are used for function approximation, then accuracy is improved, but the number of instructions and memory storage space increase

Engineering Contradiction:
Improveapproximation accuracyVSAvoidnumber of instructions
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive, complex polynomial calculations with cheap, simple linear operations. Each piecewise segment uses basic arithmetic operations (multiplication and addition) instead of expensive polynomial evaluation. These simple linear models act as disposable approximations that can be quickly evaluated and discarded, providing sufficient accuracy without the overhead of complex polynomial arithmetic.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent performs preliminary action by pre-calculating the coefficients for each piecewise linear segment and storing them in lookup tables. This pre-computation phase separates the complex work from the runtime execution, allowing the actual function approximation to proceed with simple coefficient retrieval and linear evaluation. The heavy lifting of determining optimal coefficients is done beforehand, reducing the instruction count during actual computation.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If Taylor expansions are executed, then function approximation is achieved, but processing cycles and memory usage are significantly increased

Engineering Contradiction:
Improvefunction approximation capabilityVSAvoidprocessing cycles
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent substitutes the mechanical process of Taylor expansion execution with a simpler lookup and evaluation mechanism. Instead of mechanically computing derivatives and higher-order terms during runtime, the system uses pre-computed piecewise linear coefficients stored in memory. This substitution replaces the complex mechanical computation process with a simpler information retrieval and basic arithmetic process, dramatically reducing processing cycles.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10466967B2System and method for piecewise linear approximation
Publication Date: 2019.11.05 QUALCOMM INC
  • US10466967B2 patent drawing
  • US10466967B2 patent drawing
  • US10466967B2 patent drawing

AI summary

An apparatus includes one or more registers configured to store a vector of input values. The apparatus also includes a coefficient determination unit configured to, responsive to execution by a processor of a single instruction, select a plurality of piecewise analysis coefficients. The plurality of piecewise analysis coefficients includes one or more sets of piecewise analysis coefficients, and each set of piecewise analysis coefficients corresponds to an input value of the vector of input values. The apparatus further includes arithmetic logic circuitry configured to, responsive to the execution of at least the single instruction, determine estimated output values of a function based on the plurality of piecewise analysis coefficients and the vector of input values.