AKS test for primes: Difference between revisions
→{{header|Ruby}}: Add implementation.
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(→{{header|Ruby}}: Add implementation.) |
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Primes: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103
103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 </pre>
=={{header|Ruby}}==
Using the `polynomial` Rubygem, this can be written directly from the definition in the description:
<lang ruby>require 'polynomial'
def x_minus_1_to_the(p)
return Polynomial.new(-1,1)**p
end
def prime?(p)
return false if p < 2
(x_minus_1_to_the(p) - Polynomial.from_string("x**#{p}-1")).coefs.select{|n| n%p!=0}.length == 0
end
7.times do |n|
puts "(x-1)^#{n} = #{x_minus_1_to_the(n).to_s}"
end
puts "\nPrimes below 50:", 50.times.select {|n| prime? n}.join(',')</lang>
Or without the dependency:
<lang ruby>def x_minus_1_to_the(p)
return [1] if p==0
(p-1).times.inject([1,-1]) do |ex, _|
(ex + [0]).zip([0] + ex).map { |x,y| x - y }
end.reverse
end
def prime?(p)
return false if p < 2
coeff = x_minus_1_to_the(p)
([coeff[0]+1] + coeff[1,coeff.length-2]).select{|n| n%p!=0}.length == 0
end
7.times do |n|
puts "(x-1)^#{n} = " +
x_minus_1_to_the(n).
each_with_index.
map { |c, p| "#{c}x^#{p}".sub( /^(-?)1x/, '\1x' ).sub( /\^1$/, '' ).sub( /x\^0/, '1' ) }.
join( ' + ' ).
gsub( /\+ -/, '- ' )
end
puts "\nPrimes below 50:", 50.times.select {|n| prime? n}.join(',')</lang>
=={{header|Rust}}==
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