Evaluate the primorial of a number [duplicate]

Question

The primorial of a number is the product of all the primes until that number, itself included.

Take a number from STDIN as the input and evaluate its primorial, also known as the prime factorial.

Don't use libraries. Shortest code wins.

Test cases:

Essentially the same task as Sum of primes between given range, just with multiplication instead of addition and the starting value of the range is fixed. — manatwork, May 17 '13 at 14:31

Community · Accepted Answer · 2020-06-17 09:04:33Z

5

J, 13 characters

*/p:i._1 p:1+

Examples:

   */p:i._1 p:1+7
210

   */p:i._1 p:1+12
2310

edited Jun 17 at 9:04

Community♦

1

answered May 17 '13 at 14:46

Howard

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\$\begingroup\$ Damn. Just beat me. \$\endgroup\$ – Gareth May 17 '13 at 14:46
\$\begingroup\$ Did I just see an instance of telepathy?! \$\endgroup\$ – Soham Chowdhury May 17 '13 at 14:49
6

\$\begingroup\$ @SohamChowdhury, no, you saw an instance of a trivial answer to a trivial question. \$\endgroup\$ – Peter Taylor May 17 '13 at 15:04
\$\begingroup\$ Boohoo you just trolled me. \$\endgroup\$ – Soham Chowdhury May 17 '13 at 15:19
\$\begingroup\$ Does J have a built-in way of calculating primes? \$\endgroup\$ – arshajii Jun 17 '13 at 13:36

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xnor · Accepted Answer · 2016-09-11 03:28:11Z

Python 2, 49 bytes

P=k=1
exec"P*=P**k%k<1or k;k+=1;"*input()
print P

Counts up k from 1 to the input, updating the primorial P by multiplying P by k whenever it's prime. Since P contains all lower prime factors, a sufficiently high power of P will contain k as a factor if and only if k is non-prime. The power P**k suffices, and we check whether P**k%k<1, multipling P by 1 if so (doing nothing) and by k otherwise.

Dr. belisarius · Accepted Answer · 2013-05-18 17:26:34Z

3

Mathematica, 27 chars

Times@@Prime@Range@PrimePi@

Usage

Times@@Prime@Range@PrimePi@100
(*
2305567963945518424753102147331756070
*)

edited May 18 '13 at 17:26

answered May 17 '13 at 22:27

Dr. belisarius

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\$\begingroup\$ I counted only 27 chars. \$\endgroup\$ – DavidC May 18 '13 at 16:30
\$\begingroup\$ @DavidCarraher You're right. Thanks \$\endgroup\$ – Dr. belisarius May 18 '13 at 17:26
\$\begingroup\$ Is that @ symbol at the end meant to be there? On it's own that'd be invalid syntax. You could probably just omit it. \$\endgroup\$ – numbermaniac Oct 2 '17 at 0:46

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Community · Accepted Answer · 2020-06-17 09:04:33Z

3

Mathematica 21

The large Pi represents the product function.

PrimePi@n returns the number of primes up to and including n.

Prime@i returns the ith prime.

product2

edited Jun 17 at 9:04

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1

answered May 18 '13 at 23:34

DavidC

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1

\$\begingroup\$ C'mon... the product function is one char?! That's an ingenious workaround! \$\endgroup\$ – Soham Chowdhury May 22 '13 at 16:13
\$\begingroup\$ Thanks. It's somewhat like the case of "a+b", which is shorthand for Plus[a,b] or "a.b.c", which stands for the dot product, Dot[a,b,c]. \$\endgroup\$ – DavidC May 22 '13 at 16:30

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Community · Accepted Answer · 2020-06-17 09:04:33Z

3

Python, 72 characters

Quickly golfed, I imagine there are better python solutions.

n=t=1;exec"t*=(1,n)[all(n%i for i in range(2,n))];n+=1;"*input();print t

I used wikipedia to verify up to 71

Usage:

$ python primorial.py
100
2305567963945518424753102147331756070

$ python primorial.py
101
232862364358497360900063316880507363070

edited Jun 17 at 9:04

Community♦

1

answered May 17 '13 at 15:32

ejrb

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\$\begingroup\$ Whoops, just updated it so it actually works! \$\endgroup\$ – ejrb May 20 '13 at 12:57

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Community · Accepted Answer · 2020-06-17 09:04:33Z

3

PARI/GP, 22 bytes

prodeuler(x=1,input,x)

edited Jun 17 at 9:04

Community♦

1

answered Jun 16 '13 at 14:43

Yury

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StreakyCobra · Accepted Answer · 2013-05-17 19:06:26Z

1

Haskell, 90 chars

main=getLine>>= \v->print.product.takeWhile(<=read v)$[n|n<-[2..],all((>0).rem n)[2..n-1]]

or (also 90 chars):

main=getLine>>=print.product.flip takeWhile [n|n<-[2..],all((>0).rem n)[2..n-1]].(>=).read

Compilation

ghc primorial.hs

Usage

$ echo "12" | ./primorial
2310

or

$ ./primorial
12<ENTER>
2310

edited May 17 '13 at 19:06

answered May 17 '13 at 18:57

StreakyCobra

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\$\begingroup\$ Some room for improvement here. takeWhile is unnecessary, we can just add an upper limit for the [2..] instead. Instead of getLine + read, we can use readLn. Also, do-notation is slightly shorter than using >>=. Result: main=do v<-readLn;print$product[n|n<-[2..v],all((>0).rem n)[2..n-1]] (68 characters) \$\endgroup\$ – hammar Jun 18 '13 at 21:10

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flodel · Accepted Answer · 2013-05-18 23:35:08Z

1

R - 48

x=1:scan();prod(x[rowSums(outer(x,x,`%%`)<1)<3])

answered May 18 '13 at 23:35

flodel

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Community · Accepted Answer · 2020-06-17 09:04:33Z

1

C, 125 bytes

p(n,x){return x==1?n:n%x?p(n,x-1):1;}
f(n){return n==1?1:p(n,n-1)*f(n-1);}
main(){int n;scanf("%d",&n);printf("%d\n",f(n));}

edited Jun 17 at 9:04

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1

answered May 17 '13 at 17:21

md5

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aka.nice · Accepted Answer · 2013-05-18 20:11:37Z

Smalltalk, Squeak 4.x flavour

Let's say we read n from stdin in 38 chars (this kind of requirement is just killing!)

n:=FileStream stdin nextLine asNumber.

If only product were defined in Collection in base image, this could be as simple as

^(0class primesUpTo:n+1)product

or:

^((2to:n)select:#isPrime)product

Unfortunately, we have to code #product by ourself in 48 chars (86 total).

(0class primesUpTo:n+1)inject:1into:[:p :i|p*i]

Or if primesUpTo: is considered as a library, we can use isPrime in 62 chars (100 total)

^(1to:n)inject:1into:[:p :i|i isPrime ifTrue:[p*i]ifFalse:[p]]

If even isPrime is forbidden we can find by ourselves in 67 chars (105 total)

p:=1. 2to:n do:[:i|((2to:i-1)anySatisfy:[:d|i\\d=0])or:[p:=p*i]].^p

Or for the fun, we can use a sieve in 108 chars (146 total)

s:=(p:=y:=1)<<n-2. 2to:n do:[:x|y:=(z:=y)*2+1.(z+1bitAnd:s)=0or:[p:=p*x.s:=z<<(n//x*x+x)//y+z+1bitAnd:s]].^p

Explanation of the sieve at http://smallissimo.blogspot.fr/2011/07/revisiting-sieve-of-erathostenes.html

Nota: bitAnd: has a short-cut operator & in Pharo 2.0, which would reduce Sieve cost to 94 chars (132 total)

s:=(p:=y:=1)<<n-2. 2to:n do:[:x|y:=(z:=y)*2+1.z+1&s=0or:[p:=p*x.s:=z<<(n//x*x+x)//y+z+1&s]].^p

BlackCap · Accepted Answer · 2016-09-12 11:27:38Z

0

Haskell, 76 bytes

main=interact$ \n->show$product[x|x<-[2..read n],and[x`mod`y>0|y<-[2..x-1]]]

Example:

$ echo 12 | ./primorial
2310

answered Sep 12 '16 at 11:27

BlackCap

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Community · Accepted Answer · 2020-06-17 09:04:33Z

Java 7, 213 bytes

class M{public static void main(String[]a){c(new Long(a[0]));}static void c(long n){long r=1,i=0;for(;++i<=n;r*=p(i)?i:1);System.out.print(r);}static boolean p(long n){int i=2;while(i<n)n=n%i++<1?0:n;return n>1;}}

Ungolfed:

class M{
  static void c(long n){
    long r = 1,
         i = 0;
    for (; ++i <= n; r *= p(i) ? i : 1);
    System.out.print(r);
  }

  public static void main(String[] a){
    c(new Long(a[0]));
  }

  static boolean p(long n){
    int i = 2;
    while(i < n){
      n = n % i++ < 1 ? 0 : n;
    }
    return n > 1;
  }
}

Usage: java -jar M.jar 17
Output: 510510

Anything after Java SE 7 Update 21 is disallowed for being released after the challenge was created. Make sure what you use is from that update or before. en.wikipedia.org/wiki/Java_version_history#Java_SE_7 — mbomb007, Sep 12 '16 at 16:31

Mr. Xcoder · Accepted Answer · 2017-10-01 21:08:36Z

0

Jelly, 3 bytes

ÆRP

Try it online!

answered Oct 1 '17 at 21:08

Mr. Xcoder

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Steadybox · Accepted Answer · 2017-10-01 21:10:27Z

0

MATLAB/Octave, 23 bytes

prod(primes(input('')))

Try it online!

answered Oct 1 '17 at 21:10

Steadybox

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ATaco · Accepted Answer · 2017-10-01 22:24:23Z

0

RProgN 2, 6 bytes

S²P¬-*

Explained

S²P¬-*
S       # Produce as stack from 1 to the input.
 ²  -   # Filter it by the function provided
  P¬    # Is it not a prime?
     *  # Get the product of the now list of primes.

Try it online!

answered Oct 1 '17 at 22:24

ATaco

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Community · Accepted Answer · 2020-06-17 09:04:33Z

0

Japt, 6 bytes

õ fj ×

Try it here

edited Jun 17 at 9:04

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1

answered Oct 2 '17 at 8:09

Shaggy

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Erik the Outgolfer · Accepted Answer · 2017-10-02 12:56:59Z

0

05AB1E, 3 bytes

ÅPP

Try it online!

answered Oct 2 '17 at 12:56

Erik the Outgolfer

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numbermaniac · Accepted Answer · 2017-10-11 11:33:13Z

Casio-Basic, 41 bytes

prod(seq(piecewise(isPrime(x),x,1),x,1,n

Since the calculator doesn't have a "select" function of any kind, a piecewise/hybrid function is used to return the number if it's prime, otherwise return 1. seq does this over a range of integers from 1 to n, and prod multiplies the whole list together.

40 bytes for the function, +1 byte to enter n in the parameters box.

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Evaluate the primorial of a number [duplicate]

18 Answers 18

J, 13 characters

Python 2, 49 bytes

Mathematica, 27 chars

Mathematica 21

Python, 72 characters

PARI/GP, 22 bytes

Haskell, 90 chars

Compilation

Usage

R - 48

C, 125 bytes

Haskell, 76 bytes

Java 7, 213 bytes

Jelly, 3 bytes

MATLAB/Octave, 23 bytes

RProgN 2, 6 bytes

Explained

Japt, 6 bytes

05AB1E, 3 bytes

Casio-Basic, 41 bytes

Not the answer you're looking for? Browse other questions tagged code-golf number arithmetic number-theory primes or ask your own question.

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Evaluate the primorial of a number [duplicate]

18 Answers 18

J, 13 characters

Python 2, 49 bytes

Mathematica, 27 chars

Mathematica 21

Python, 72 characters

PARI/GP, 22 bytes

Haskell, 90 chars

Compilation

Usage

R - 48

C, 125 bytes

Haskell, 76 bytes

Java 7, 213 bytes

Jelly, 3 bytes

MATLAB/Octave, 23 bytes

RProgN 2, 6 bytes

Explained

Japt, 6 bytes

05AB1E, 3 bytes

Casio-Basic, 41 bytes

Not the answer you're looking for? Browse other questions tagged code-golf number arithmetic number-theory primes or ask your own question.

Linked

Related

Hot Network Questions