System and method for improving the accuracy of reciprocal square root operations performed by a floating-point unit
US6912559B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 1999 |
| Grant date | Jun 28, 2005 |
| Priority date | — |
| Expiry date | Dec 12, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F7/4876
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The accuracy of approximating the reciprocal and the reciprocal square root of a number (N) is improved. Approximating the reciprocal of N includes: (a) estimating the reciprocal of N to produce an estimate (Xi); (b) determining a first intermediate result (IR1) according to the equation: IR1=1−N*Xi; (c) multiplying IR1 by Xi to produce a second intermediate result (IR2); and (d) adding Xi to IR2 to produce an approximation of the reciprocal of N. Approximating the reciprocal square root includes: (a) estimating the reciprocal square root of N to produce Xi; (b) multiplying Xi by N to produce IR1; (c) determining IR2 according to the equation: IR2=(1−Xi*IR1)/2; (d) multiplying IR2 by Xi to produce a third intermediate result (IR3); and (e) adding IR3 to Xi to produce an approximation of the reciprocal square root of the number.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.