International Business Machines Corporation

Freg G Gustavson

Ramesh Chandra Agarwal

Andrew Augustus Bjorksten

A method and system for performing floating-point division of a dividend by a divisor within a floating-point unit having multiply and add functions are disclosed. In performing floating-point division, a quotient having a mantissa is produced. The method uses an approximation based on a linear approximation stored within a first table. The first approximation approximates two divided by the divisor. A second table value is also selected from the table lookup. The second table value approximates the reciprocal of the divisor squared. Both the first and second table values operate as linear correction terms. Also according to the present invention, a method and system are disclosed that perform an early exit check during the division operation to confirm whether the resultant quotient has an acceptable accuracy and if the accuracy is unacceptable, then perform a rounding correction based upon a given rounding boundary.

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Briarcliff Manor, NY, United States of America

Freg G Gustavson