Talk:Modular exponentiation: Difference between revisions
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My draft currently specifies m ≠ 0. The answer when m < 0 might be ill-defined or inconsistent. Should I change from m ≠ 0 to m > 0 here? --[[User:Kernigh|Kernigh]] 23:18, 20 December 2011 (UTC) |
My draft currently specifies m ≠ 0. The answer when m < 0 might be ill-defined or inconsistent. Should I change from m ≠ 0 to m > 0 here? --[[User:Kernigh|Kernigh]] 23:18, 20 December 2011 (UTC) |
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: You could specify them all to be positive integers without causing problems; that's the only case that anyone actually wants in practice, and the others get into arguments (due to differing interpretations of how to extend the modulus operation to non-positive-valued domains). –[[User:Dkf|Donal Fellows]] 02:00, 21 December 2011 (UTC) |
: You could specify them all to be positive integers without causing problems; that's the only case that anyone actually wants in practice, and the others get into arguments (due to differing interpretations of how to extend the modulus operation to non-positive-valued domains). –[[User:Dkf|Donal Fellows]] 02:00, 21 December 2011 (UTC) |
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== Tell algorithm? == |
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What's with needs improvement on the Java solution? A number of other solutions here just call a library function. In general, library algorithms might not always be known, or may change without notice so I'm not a big fan of telling library algorithms. As with so many other tasks, this one could go in different directions: Allowing simple library solutions, disallowing simple library solutions, or requiring a specific algorithm. The [[en.wikipedia.org/wiki/Modular_exponentiation#Right-to-left_binary_method|binary]] algorithm is an important one. It wouldn't be so bad to require an implementation of that specific algorithm. —[[User:Sonia|Sonia]] 18:19, 24 December 2011 (UTC) |
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Revision as of 18:19, 24 December 2011
Draft change
About 21 hours after I posted this draft, I changed the task from "last 20" to "last 40 decimal digits". I adjusted some solutions to print 40 digits, but I did not change the Go or Java programs. --Kernigh 19:49, 19 December 2011 (UTC)
What if m < 0?
My draft currently specifies m ≠ 0. The answer when m < 0 might be ill-defined or inconsistent. Should I change from m ≠ 0 to m > 0 here? --Kernigh 23:18, 20 December 2011 (UTC)
- You could specify them all to be positive integers without causing problems; that's the only case that anyone actually wants in practice, and the others get into arguments (due to differing interpretations of how to extend the modulus operation to non-positive-valued domains). –Donal Fellows 02:00, 21 December 2011 (UTC)
Tell algorithm?
What's with needs improvement on the Java solution? A number of other solutions here just call a library function. In general, library algorithms might not always be known, or may change without notice so I'm not a big fan of telling library algorithms. As with so many other tasks, this one could go in different directions: Allowing simple library solutions, disallowing simple library solutions, or requiring a specific algorithm. The binary algorithm is an important one. It wouldn't be so bad to require an implementation of that specific algorithm. —Sonia 18:19, 24 December 2011 (UTC)