Electrical computers: arithmetic processing and calculating – Electrical digital calculating computer – Particular function performed
Reexamination Certificate
2007-12-31
2011-11-29
Bullock, Jr., Lewis (Department: 2193)
Electrical computers: arithmetic processing and calculating
Electrical digital calculating computer
Particular function performed
C708S496000, C708S525000, C708S551000
Reexamination Certificate
active
08069199
ABSTRACT:
Methods and arrangements to correct for double rounding errors when rounding floating point numbers to nearest even are described. Embodiments include transformations, code, state machines or other logic to perform a floating point operation on one or more floating point numbers of precision P1in base b, producing positive result res0of precision greater than precision P1; rounding positive result res0to precision P1to the nearest even, producing positive result res1; and rounding the result res1to precision P2to the nearest even, where P2is narrower than P1, producing result res2. The embodiments may also include correcting res2for double rounding errors. The correcting may include determining that res1is midway between two consecutive floating point numbers of precision P1, the larger (smaller) being res2, determining that rounding res0to produce res1involved rounding up (down), and decrementing (incrementing) the significand of res2to obtain the corrected result res2′.
REFERENCES:
patent: 6512523 (2003-01-01), Gross
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Bullock, Jr. Lewis
Intel Corporation
Sandifer Matthew
Schubert Law Group PLLC
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