Method and data processor for finding a logarithm of a number
US5570310A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 5, 1994 |
| Grant date | Oct 29, 1996 |
| Priority date | — |
| Expiry date | Dec 5, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F7/556
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A data processor and method are used to find log.sub.p (x) wherein p is a numerical base and x is a floating point value. The method begins by deriving a number y from the quantity x wherein the number y has a predetermined sign portion, a predetermined exponent portion, and the fraction portion f. The predetermined fraction portion f being a truncated portion of x. A logarithm to the predetermined base p of the number y is found by calculating: EQU log.sub.p (y)=-log.sub.p (a)+log.sub.p (1+(ay-1)) where the constant a is read from a memory table of constants indexed by an index i. Index i is calculated from y where the fraction portion f of y lies in the range of 1.ltoreq.y<2 and the position in this range determines index i. The log.sub.p (y), once determined, is used to find the log.sub.p (x) in an accurate manner as indicated in equation 16 herein.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.