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1. (WO2018044505) APPROXIMATION OF NONLINEAR FUNCTIONS IN FIXED POINT USING LOOKUP TABLES 


IPC:  G06F 17/17 G06F 7/544 

Applicants:  QUALCOMM INCORPORATED 

Inventors:  LIN, Dexu LIAO, Edward MAJUMDAR, Somdeb LAMB, Aaron CHATHA, Karamvir 
Title:  APPROXIMATION OF NONLINEAR FUNCTIONS IN FIXED POINT USING LOOKUP TABLES 
Abstract: 
Computing a nonlinear function f(x) in hardware or embedded systems can be complex and resource intensive. In one or more aspects of the disclosure, a method, a computerreadable medium, and an apparatus are provided for computing a nonlinear function f(x) accurately and efficiently in hardware using lookup tables (LUTs) and interpolation or extrapolation. The apparatus may be a processor. The processor computes a nonlinear function f(x) for an input variable x, where f(x)=g(y(x),z(x)). The processor determines an integer n by determining a position of a most significant bit (MSB) of an input variable x. In addition, the processor determines a value for y(x) based on a first lookup table and the determined integer n. Also, the processor determines a value for z(x) based on n and the input variable x, and based on a second lookup table. Further, the processor computes f(x) based on the determined values for y(x) and z(x).
