Anonymous user
Talk:Miller–Rabin primality test: Difference between revisions
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→Erlang
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== Erlang ==
Miller-Rabin primality test in Erlang uses a floating point power function and truncation to restore to integer. This combination begins to fall short when the integer being tested is up to approximately 90,000,000. At these large sizes, the primes found are correct but too many correct primes are not found.
-module(power). %%% Add this integer power function to use in place of math:pow/2 in the main procedure.
-export([power/2]).
power(X, N) ->
power(X, N, 1).
power(X, N, Acc) ->
if
N /= 0 -> power(X, N - 1, X * Acc);
true -> Acc
end.
%%% Modify mr_series/4 to read as follows:
mr_series(N, A, D, S) when N rem 2 == 1 ->
Js = lists:seq(0, S),
lists:map(fun(J) -> pow_mod(A, power:power(2, J)*D, N) end, Js).
%%% Modify pow_mod/3 to read as follows:
pow_mod(B, E, M) ->
case E of
0 -> 1;
_ -> case ((E rem 2) == 0) of
true -> (power:power(pow_mod(B, (E div 2), M), 2)) rem M;
false -> (B*pow_mod(B, E-1, M)) rem M
end
end.
%%% END OF NOTE
== Tcl ==
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