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Talk:Iterated digits squaring: Difference between revisions
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I downloaded a D compiler and produced my first program in D here [[Combinations with repetitions/Square Digit Chain]]. It uses the combRep procedure defined here [[Combinations with repetitions]]. I suggest this shows that the cobanatronics in this task is a duplication of work already produced in [[Combinations with repetitions]]. I would like to change the task description to require a function which when given a number returns true or false indicating that that number translates to 1 or not according to the rules for square digit number chaining, and to demonstrate the function by counting the number which translate to 1 upto the Project Euler #92 limit of 10**7. No special coding being required for speed, de-emphasizing the timing and emphasizing that a large n in the chain rapidly becomes a small n, but a small n may become a slightly larger n for a time.--[[User:Nigel Galloway|Nigel Galloway]] ([[User talk:Nigel Galloway|talk]]) 11:26, 18 September 2014 (UTC)
==ProjectEuler92==
The carefully worded PE challenge says that the sequence "attains" rather than "ends with" 1 or 89.
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Also, ''Project Euler 92'' requested:
:: <big> How many starting numbers '''below''' ten million will arrive at 89? </big>
(Bold lettering added by me). -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 00:38, 25 May 2015 (UTC)
== Dup? ==
While the example results asked for in this task are different, this task seems quite similar to [[Happy_numbers|Happy numbers]]. This suggests one of several possible approaches:
# Merge the tasks
# Cross reference the tasks
# Create a category for the tasks
# Pretend it didn't happen
# Pretend it did happen, but do nothing anyway.
I'm not sure which of these we should choose... --[[User:Rdm|Rdm]] ([[User talk:Rdm|talk]])
: I don't think merging the tasks will simplify anything. Especially at this late date for two bona fide, full-fledged Rosetta Code tasks. Creating a category for the tasks, I think, would be nice. You could add a 5<sup>th</sup> option: Pretend it did happen, but do nothing anyway. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 23:01, 13 September 2015 (UTC)
:: Added. --[[User:Rdm|Rdm]] ([[User talk:Rdm|talk]]) 23:05, 13 September 2015 (UTC)
: Since '''happy numbers''' have their own name and are referenced in/on publications and other web-sites, they deserve their own algorithms (without generalizing them). Similar to primes, K-primes, almost-primes, pseudo-primes, phi (totient), divisors (tau), proper divisors (aliquot), and the like; they are both generalizations of ''factoring''. Similarly with factorials and multi-factorials, and the many variants of Fibonacci series (the Lucas series being one of them). -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 23:22, 13 September 2015 (UTC)
:: Ok, but I do not understand what factoring has to do with sums of squares of digits... --[[User:Rdm|Rdm]] ([[User talk:Rdm|talk]]) 02:57, 14 September 2015 (UTC)
::: Nothing at all. I was generalizing about various primes and factoring, not squares of digits and factoring. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 03:04, 14 September 2015 (UTC)
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