Internal use. An implementation of eratosthenes's sieve

Methods
N
Included Modules
Constants
BITS_PER_ENTRY = 16
 
NUMS_PER_ENTRY = BITS_PER_ENTRY * 2
 
ENTRIES_PER_TABLE = 8
 
NUMS_PER_TABLE = NUMS_PER_ENTRY * ENTRIES_PER_TABLE
 
FILLED_ENTRY = (1 << NUMS_PER_ENTRY) - 1
 
Instance Public methods
next_to(n)

returns the least odd prime number which is greater than n.

Source: show | on GitHub 

# File lib/prime.rb, line 441
def next_to(n)
  n = (n-1).div(2)*2+3 # the next odd number to given n
  table_index, integer_index, bit_index = indices(n)
  loop do
    extend_table until @tables.length > table_index
    for j in integer_index...ENTRIES_PER_TABLE
      if !@tables[table_index][j].zero?
        for k in bit_index...BITS_PER_ENTRY
          return NUMS_PER_TABLE*table_index + NUMS_PER_ENTRY*j + 2*k+1 if !@tables[table_index][j][k].zero?
        end
      end
      bit_index = 0
    end
    table_index += 1; integer_index = 0
  end
end