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Talk:Semiprime: Difference between revisions
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→a graphic view of the first 10k semi-primes: added a comment.
(section added on the use of natural numbers phrase. -- ~~~~) |
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Of course, if all program examples would handle both cases, this would be a moot point. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 01:17, 21 February 2014 (UTC)
:It doesn't matter ''when taken in this context''. Zero is never taken as prime.
:: That was never my point. Unity also isn't a prime. But an '''isPrime''' function should be able to test any integer and return a correct result (as to being a prime or not) without giving an error or causing a loop. Same thing with an ''isSemiprime'' function. It should be able to return a correct result. Understanding that extremely large numbers would be problematic, of course. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 08:00, 21 February 2014 (UTC)
:Are you saying that the task description is confusing as it stands? --[[User:Paddy3118|Paddy3118]] ([[User talk:Paddy3118|talk]]) 07:17, 21 February 2014 (UTC)
:: Well, maybe not confusing, but it could be clarified. The use of any phrase (or word) that is under contention (disagreement) should never be used in a definition. If not, then we could say that semiprimes are the product of exactly two (possibly equal) primes. The use of a clarifying adjective should be definitive, and not be argumentative (since there is not an agreed-on definition). I like Mathworld's definition better: a semiprime, also called a 2-almost prime, biprime, or ''p q''-number, is a composite number that is the product of two (possible equal) primes. This also has the advantage of introducing other (alias) names for people searching for alternate names. A note about the square of a prime being, by definition, is a semiprime would be a nice addition. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 08:00, 21 February 2014 (UTC)
:::I don't agree with "The use of any phrase (or word) that is under contention (disagreement) should never be used in a definition". Context and audience mean a lot. --[[User:Paddy3118|Paddy3118]] ([[User talk:Paddy3118|talk]]) 09:04, 21 February 2014 (UTC)
== a graphic view of the first 10k semi-primes ==
For those that are interested, here is the output of my '''$CALC''' (REXX) program that shows a binary map of the first 10k semiprimes.
<br><br>The command used was: (extra blanks were used to make the command's arguments easier to read)
$CALC trans{ isSemiPrime[ iota(10k) ], 'fefa'x, 10} ;;; SQUISH GRoup 100
The '''isSemiPrime''' BIF outputs a '''0''' (zero) to indicate the number isn't semi-prime, or a '''1''' (unity) to indicate a semi-prime.
The '''translate''' BIF converts (for easier perusing) ones and zeroes to ■ and <b> · </b> [the square bullets are the semi-primes].
The '''iota''' BIF generates the numbers 1 ──► 10,000 which are passed to the '''isSemiPrime''' BIF.
The '''SQUISH''' option removes all blanks from the output (except for the index).
The '''GROUP''' option groups '''100''' output items per line.
(Output is shown at <sup>'''2'''</sup>/<sub>3</sub> size.)
<pre style="font-size:67%">
╔═══════════════════════════════════════════════╗
║ trans{ isSemiPrime[ iota(10k) ], 'fefa'x, 10} ║
╚═══════════════════════════════════════════════╝
1► ···■·■··■■···■■·····■■··■■······■■■··■■······■··■·■···■·■■···■··■···■····■··■····■··■■■···■·■■■·····
101► ·····■····■···■··■■·■■■·····■···■■······■■■·■■········■··■■·■····■··■·······■■····■·■·■······■······
201► ■■■·■■··■···■■■·■■■·■····■········■·■·········■·■···■■····■··■··■·■······■···■········■·■·■···■··■■·
301► ■■■·■···■····■····■·■·■··■■·■····■■···■·■····■········■··■··■■··■·····■·····■···■■···■····■·■■■··■··
401► ··■···■···■·■·■·■····■····■·········■·······■■■···■·■■···■·······■··■·■·■····■··■■··■···■···■···■···
501► ■■··■·····■··■■·■·■······■■·■···■·■·■■···■■·■·····■·■■····■··■··■■······■·····■·■·■··■··■·■·····■···
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901► ■···■·······■■··■···■■■··■······■■····■···■·····■·■···■··■■·■···■·······■■····■··■··■···■···■·■··■··
1001► ··■··■■···■······■········■·········■···■■■··■■·······■·■·■·······■·····■···■·■·■■···········■····■·
1101► ■·········■··■■···■·■····■······■·■·■■■·■■··■·■·■····■··■·■·····■·■·■····■··■········■··■·■···■··■■·
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1301► ·····■······■·■·■■···■······■···■···■·■···■·■■■·■·■··■■·■·····■··■··■·■·······■··■■·■·■·■·■·■···■···
1401► ■■■·■·····■···■·■■··················■■··■············■··■···■···■■··■···■···■■·······■··········■···
1501► ■■····■·■···■■··■····■····■·■·····■·■■··■····■········■·····■·■·■···■····■··■·······■···■·■··■······
1601► ··■··············■···■■·······■·■·····■·■■■··■··■·■··■■··■··■·········■·■····■■·■···■·■·■·■·········
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2101► ■■■·■···········■·■··■■··■■··········■········■·■·····■·■·■·····■·■···■·■■··■···■■■··■··■·■··■■···■·
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</pre>
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