What is the fastest algorithm for division of crazy large integers?

algorithm math byte division digit
Kosmos picture Kosmos · Jun 26, 2013 · Viewed 17.8k times · Source

I need to divide numbers represented as digits in byte arrays with non standard amount of bytes. It maybe 5 bytes or 1 GB or more. Division should be done with numbers represented as byte arrays, without any conversions to numbers.

Answer

tmyklebu picture tmyklebu · Jun 26, 2013

Divide-and-conquer division winds up being a whole lot faster than the schoolbook method for really big integers.

GMP is a state-of-the-art big-number library. For just about everything, it has several implementations of different algorithms that are each tuned for specific operand sizes.

Here is GMP's "division algorithms" documentation. The algorithm descriptions are a little bit terse, but they at least give you something to google when you want to know more.

Brent and Zimmermann's Modern Computer Arithmetic is a good book on the theory and implementation of big-number arithmetic. Probably worth a read if you want to know what's known.

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