Lucas-Lehmer test: Difference between revisions
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=={{header|Scala}}== |
=={{header|Scala}}== |
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[[Category:Scala Implementations]] |
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{{works with|Scala|2.9.1}} |
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{{libheader|Scala}} |
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In accordance with definition of Mersenne primes it could only be a Mersenne number with prime exponent. |
In accordance with definition of Mersenne primes it could only be a Mersenne number with prime exponent. |
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<lang Scala>object LLT extends App { |
<lang Scala>object LLT extends App { |
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import Stream._ |
import Stream._ |
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def primeSieve(s: Stream[Int]): Stream[Int] = |
def primeSieve(s: Stream[Int]): Stream[Int] = |
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s.head #:: primeSieve(s.tail filter { _ % s.head != 0 }) |
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val primes = primeSieve(from(2)) |
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def mersenne(p: Int): BigInt = (BigInt(2) pow p)-1 |
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def mersenne(p: Int): BigInt = (BigInt(2) pow p) - 1 |
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( |
def s(mp: BigInt, p: Int): BigInt = { if (p == 1) 4 else ((s(mp, p - 1) pow 2) - 2) % mp } |
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val upbPrime = 9999 |
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println(s"Finding Mersenne primes in M[2..$upbPrime]") |
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((primes takeWhile (_ < upbPrime)).par map { p => (p, mersenne(p)) } |
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map { p => if (p._1 == 2) (p, 0) else (p, s(p._2, p._1 - 1)) } filter { _._2 == 0 }) |
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.foreach { p => |
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println(s"prime M${(p._1)._1}: " + |
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} |
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println("That's All Folks!") |
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}</lang> |
}</lang> |
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{{out}} |
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Output: |
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<pre style="height: 30ex; overflow: scroll"> |
<pre style="height: 30ex; overflow: scroll">Finding Mersenne primes in M[2..9999] |
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prime M2: 3 |
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prime M3: 7 |
prime M3: 7 |
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prime M5: 31 |
prime M5: 31 |
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prime M4423: (1332 digits) |
prime M4423: (1332 digits) |
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prime M9689: (2917 digits) |
prime M9689: (2917 digits) |
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prime M9941: (2993 digits) |
prime M9941: (2993 digits) |
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That's All Folks!</pre> |
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=={{header|Scheme}}== |
=={{header|Scheme}}== |
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