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Patents

HP Patents Bignum Implementation From 1912 144

I Don't Believe in Imaginary Property writes "The authors of GMP (the GNU Multiple Precision Arithmetic Library) were invited to join Peer-to-Patent to review HP's recent patent on a very old technique for implementing bignums because their software might infringe. Basically, HP's patent claims choosing an exponent based on processor word size. If you choose a 4-bit word size and a binary number, you end up working in hexadecimal. Or for a computer with a 16-bit word and a base-10 number, you use base 10,000 so that each digit of the base-10,000 number would fit into a single 16-bit word. The obvious problem with that is that there's plenty of prior art here. Someone who spent a few minutes Googling found that Knuth describing the idea in TAOCP Vol. 2 and other citations go back to 1912 (which implemented the same algorithm using strips of cardboard and a calculating machine). None of this can be found in the 'references cited' section. Even though the patent examiner did add a couple of references, they appear to have cited some old patents. The patent issued a few months ago was filed back in October of 2004, and collected dust at the USPTO for some 834 days."

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