lambdaway :: anti

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_h1 anti primes

_p Following [[rosetta|https://rosettacode.org/wiki/Anti-primes]] the anti-primes  are the natural numbers with more factors than any smaller than itself.

_h2 javascript via lambdatalk

{prewrap
1) building a javascript primitive:

'{script 
LAMBDATALK.DICT['jsgenerateAntiprimes'] = function() {
  function factors(n) {
    var factors = [];
    for (var i = 1; i <= n; i++) {
      if (n % i == 0) {
        factors.push(i);
      }
    }
    return factors;
  }

2) usage:

'{jsgenerateAntiprimes 20}
-> 
1,2,4,6,12,24,36,48,60,120,180,240,360,720,840,1260,1680,2520,5040,7560  // in 100ms
}

_h2 lambdatalk

{prewrap

'{def factors
 {def factors.filter
  {lambda {:n :a :i}
   {if {= {% :n :i} 0} 
    then {A.addlast! :i :a}
    else}}}
 {lambda {:n}
  {S.last
   {S.map {factors.filter :n {A.new}}
          {S.serie 1 :n}}}}} 
-> {def factors
 {def factors.filter
  {lambda {:n :a :i}
   {if {= {% :n :i} 0} 
    then {A.addlast! :i :a}
    else
 }}}
 {lambda {:n}
  {S.last
   {S.map {factors.filter :n {A.new}}
          {S.serie 1 :n}}}}}

'{factors 7500}
-> [1,2,3,4,5,6,10,12,15,20,25,30,50,60,75,100,125,150,250,300,375,500,625,750,1250,1500,1875,2500,3750,7500] 
// in 70ms

'{def antiprimes
 {def antiprimes.filter
  {lambda {:ap :max :i} 
   {let { {:ap :ap} {:max :max} {:i :i} 
          {:len {A.length {factors :i}}}
        } {if {> :len {A.get 0 :max}}
           then {A.addlast! :i :ap} 
                {A.set! 0 :len :max}
           else} }}}
 {lambda {:n}
  {S.first
   {S.map {antiprimes.filter {A.new 1} {A.new 1}}
          {S.serie 1 :n}}}}} 
-> {def antiprimes
 {def antiprimes.filter
  {lambda {:ap :max :i} 
            {let { {:ap :ap} {:max :max} {:i :i} 
                   {:len {A.length {factors :i}}}
                 } {if {> :len {A.get 0 :max}}
                    then {A.addlast! :i :ap} 
                         {A.set! 0 :len :max}
                    else} }}}
 {lambda {:n}
  {S.first
   {S.map {antiprimes.filter {A.new 1} {A.new 1}}
          {S.serie 1 :n}}}}}

'{antiprimes 8000}
-> [1,2,4,6,12,24,36,48,60,120,180,240,360,720,840,1260,1680,2520,5040,7560]   
// in 105400ms on my iPad
}

{script

LAMBDATALK.DICT['jsgenerateAntiprimes'] = function() {
function factors(n) {
  var factors = [];
  for (var i = 1; i <= n; i++) {
    if (n % i == 0) {
      factors.push(i);
    }
  }
  return factors;
}

}