mvw

#!/usr/bin/env ruby

def concat(n0)
  s = String.new
  n = 0
  i = 1
  while n < n0
    ds = i.to_s
    s += ds
    n += ds.length

mvw

#!/usr/bin/ruby
# cuberots.rb

class Permutation
  attr_accessor :s
  attr_accessor :h

  def initialize(s = '12345678')
    @s = s

mvw

rots = [
  k = 1: e=12345678 []
  k = 2: x=56218734 []
  k = 3: y=41238567 []
  k = 4: z=26731584 []
]
k = 1: 0 e -> e=12345678
k = 2: 1 x -> x=56218734
k = 3: 2 y -> y=41238567
k = 4: 3 z -> z=26731584

mvw

#!/usr/bin/ruby
# gravnet.rb

require "matrix"

# simplified gravitational force (G=m=M=1.0)
# from (i,j) to r
def fij(i, j, r)
  # difference vector
  rij = Vector[i,j] - r

mvw

n = 98: r = Vector[0.5, 0.5], F = Vector[-0.014357405607155703, -0.01435740560715777]
n = 99: r = Vector[0.5, 0.5], F = Vector[-0.014213111904535183, -0.014213111904536712]
n = 100: r = Vector[0.5, 0.5], F = Vector[-0.014071689664539606, -0.01407168966453928]

n = 98: r = Vector[0.25, 0.25], F = Vector[-4.6817100348218865, -4.6817100348219425]
n = 99: r = Vector[0.25, 0.25], F = Vector[-4.681637888660634, -4.681637888660691]
n = 100: r = Vector[0.25, 0.25], F = Vector[-4.681567178203503, -4.681567178203558]

n = 98: r = Vector[0.25, 0.0], F = Vector[-14.708761955833403, -1.0966027348333074e-16]
n = 99: r = Vector[0.25, 0.0], F = Vector[-14.7086898091545, 1.0235546134620965e-16]

mvw

#!/usr/bin/env ruby

# http://stackoverflow.com/q/32568996/2579220

# examples
$m = 1234567890
$n = 2345678901
$z = 987654304

$m2 = 0

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m = 42, n = 314
brute force: 57
recursive  : 57
success

m = 532, n = 7561
brute force: 2103
recursive  : 2103
success

mvw

#!/usr/bin/env ruby

require 'time'

def to_dna(i)
  s = sprintf("%012d", i.to_s(4)) 
  s.gsub!('0', 'A')
  s.gsub!('1', 'C')
  s.gsub!('2', 'G')
  s.gsub!('3', 'T')

mvw

1: AAAAACGTATAC [4]
2: AAAACGTATACA [4]
3: AAAACGTATACC [4]
4: AAAACGTATACG [4]
5: AAAACGTATACT [4]
6: AAACACGTATAC [4]
7: AAACGTATACAA [4]
8: AAACGTATACAC [4]
9: AAACGTATACAG [4]
10: AAACGTATACAT [4]

mvw

#!/usr/bin/env ruby

n = 10

def test(u, re, goal)
  r = (u =~ re).is_a? Integer
  err = (r != goal)
  w = err ? " ERROR" : ""
  d_e = err ?  1 : 0
  return r, w, d_e