Talk:Long multiplication: Difference between revisions
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(→Wrong algorithms: Append to my previous comment.) |
(→Wrong algorithms: added comment about limits for REXX. -- ~~~~) |
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For these examples, I would like some assurance that the outside algorithm really is long multiplication, and not some other algorithm (such as Karatsuba or Toom multiplication). Examples that use the wrong algorithm are incorrect. Further, I would like to clarify the task, to prohibit the use of outside algorithms, unless those algorithms do long multiplication. I think that [[Arbitrary-precision integers (included)]] is a better place to call outside algorithms. --[[User:Kernigh|Kernigh]] 00:36, 20 March 2012 (UTC)
: What kind of assurance would be acceptable? Since I wrote my personal assurance of REXXes algorithm, it was ''still'' flagged as incorrect. I've been using REXX for over 30 years and it was always thus. I've seen the original (assembler) source. REXX does explicit long multiplication (as well as addition, subtraction, and division). -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 06:55, 13 May 2013 (UTC)
At the moment, I believe that <math>2^{64}</math> and <math>2^{128}</math> are so small that most outside algorithms would use long multiplication. (In [[MRI]] Ruby, the threshold for Karatsuba multiplication seems to be around <math>2^{2240}</math> or <math>2^{4480}</math>.) --[[User:Kernigh|Kernigh]] 03:03, 20 March 2012 (UTC)
: REXX can handle (at least up to) 2^2,111,222,333 using exact multiplication. I'm not vouching for how long it takes. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 06:55, 13 May 2013 (UTC)
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