System and method for calculating floating point exponential values in a geometry accelerator
US5926406A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1997 |
| Grant date | Jul 20, 1999 |
| Priority date | — |
| Expiry date | Apr 30, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F7/483
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A novel system and method computes a floating point value of an exponential expression in the form of "a.sup.x " in a geometry accelerator. In accordance with one aspect of the invention, the method includes the steps of receiving the values "a" and x of the exponential expression, where both "a" and x are represented in floating point format. As will be appreciated by those skilled in the art, the values will by supplied by software through an appropriate graphics application program interface (API). The method utilizes a mantissa value of the floating point representation of "a" to index a first value in a first look-up table, the value being an approximation for log2(a). Then, the method multiplies the looked-up value by the value of x to obtain an intermediate result. This intermediate result is then partitioned into a fractional component and an integer component, wherein the fractional component is normalized/converted to floating point format. The method then utilizes a mantissa value of the floating point representation of the fractional component of the intermediate result to index a first value in a second look-up table, the value being an approximation for 2.sup.fract, w…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.