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Lucas-Lehmer test: Difference between revisions
m
→{{header|Python}}: straight from A68 ☺ ... python does rather well with arbitary precision, fast too.
(→{{header|ALGOL 68}}: calculate all Mersenne primes up to the implementation's max precision, or the 45th Mersenne prime. (Which ever comes first).) |
m (→{{header|Python}}: straight from A68 ☺ ... python does rather well with arbitary precision, fast too.) |
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Output:
Finding Mersenne primes in M[2..500]:
M2 M3 M5 M7 M13 M17 M19 M31 M61 M89 M107 M127
=={{header|Python}}==
from sys import stdout
from math import sqrt, log
fi = od = None
def is_prime ( p ):
if p == 2 : return True
elif p <= 1 or p % 2 == 0 : return False
else:
prime = True;
for i in range(3, int(sqrt(p))+1, 2 ):
# print "p:",p
if p % i == 0 : return False
else:
return True
fi
fi;
def is_mersenne_prime ( p ):
if p == 2 : return True
else:
m_p = 2 ** p - 1; s = 4;
for i in range(3, p+1):
s = (s * s - 2) % m_p
od;
return s == 0
fi;
precision = 20000;
long_long_bits_width = precision / log(2) * log(10);
upb_prime = int( long_long_bits_width - 1 ) / 2; # no unsigned #
upb_count = 45; # find 45 mprimes if int has enough bits #
print ((" Finding Mersenne primes in M[2..%d]: "%upb_prime));
count=0;
for p in range(2, upb_prime+1):
if is_prime(p) :
if is_mersenne_prime(p) :
stdout.write(" M%d"%p);
stdout.flush();
count += 1
fi
fi;
if count >= upb_count : break; fi
od
Output:
Finding Mersenne primes in M[2..33218]:
M2 M3 M5 M7 M13 M17 M19 M31 M61 M89 M107 M127 M521 M607 M1279 M2203 M2281 M3217 M4253 M4423 M9689 M9941 M11213 M19937 M21701 M23209
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