Abstract: A set of instructions for implementation in a floating-point unit or other computer processor hardware is disclosed herein. In one embodiment, an extended-range fused multiply-add operation, a first look-up operation, and a second look-up operation are each embodied in hardware instructions configured to be operably executed in a processor. These operations are accompanied by a table which provides a set of defined values in response to various function types, supporting the computation of elementary functions such as reciprocal, square, cube, fourth roots and their reciprocals, exponential, and logarithmic functions. By allowing each of these functions to be computed with a hardware instruction, branching and predicated execution may be reduced or eliminated, while also permitting the use of distributed instructions across a number of execution units.

Abstract: A method and arrangements for increased precision in the computation of a reciprocal square root is disclosed. In accordance with the present invention, it is possible to achieve fifty three (53) bits of precision in less processing time than previously possible.

Abstract: A processor for performing a multiply-add instruction on a multiplicand A, a multiplier B, and an addend C, to calculate a result D. The operands are double-precision floating point numbers and the result D is a canonical-form extended-precision floating point number having a high order component and a low order component. The processor is a fused multiply-add processor with a multiplier, an adder, a normalizer and a rounder. The post-adder data path, the normalizer and the rounder each have a data width sufficient to represent post-adder intermediate results to permit the high and low order words of a correctly-rounded result D to be computed. The mantissas of the extended-precision result D are provided such that the high order word mantissa is stored to double precision registers.

Abstract: A processor for performing a multiply-add instruction on a multiplicand A, a multiplier B, and an addend C, to calculate a result D. The operands are double-precision floating point numbers and the result D is a canonical-form extended-precision floating point number having a high order component and a low order component. The processor is a fused multiply-add processor with a multiplier, an adder, a normalizer and a rounder. The post-adder data path, the normalizer and the rounder each have a data width sufficient to represent post-adder intermediate results to permit the high and low order words of a correctly-rounded result D to be computed. The mantissas of the extended-precision result D are provided such that the high order word mantissa is stored to double precision registers.

Abstract: Disclosed herein are a computer-processing method and apparatus for computing values of polynomials or rational functions. A mathematical software library can advantageously embody the concepts of this invention. The method can be adapted to compute values for non-elementary,special functions, for example ERF, ERFC, LGAMMA, and Bessel functions.