Lucas-Lehmer test: Difference between revisions

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=={{header|Python}}==

from sys import stdout

<python> from sys import stdout

from math import sqrt, log

fi = od = None

def is_prime ( p ):

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elif p <= 1 or p % 2 == 0: return False

else:

⚫

for i in range(3, int(sqrt(p))+1, 2 ):

⚫

~~prime =~~ True;

⚫

for i in range(3, int(sqrt(p))+1, 2 ): ~~# do~~

if p % i == 0: return False

~~else:~~

return True

fi

fi;

def is_mersenne_prime ( p ):

if p == 2: ~~return True~~

if p == 2:

⚫

return True

else:

m_p = ( 1 << p ) - 1~~; s = 4~~;

m_p = ( 1 << p ) - 1;

~~for~~ i ~~in range(3, p+1): # do~~

s = 4;

for i in range(3, p+1):

s = (s ** 2 - 2) % m_p

od;

return s == 0

fi;

precision = 20000; # maximum requested number of decimal places of 2 ** MP-1 #

precision = 20000 # maximum requested number of decimal places of 2 ** MP-1 #

long_bits_width = precision / log(2) * log(10);

long_bits_width = precision / log(2) * log(10)

upb_prime = int( long_bits_width - 1 ) / 2; # no unsigned #

upb_prime = int( long_bits_width - 1 ) / 2 # no unsigned #

upb_count = 45; # find 45 mprimes if int was given enough bits #

upb_count = 45 # find 45 mprimes if int was given enough bits #

print ((" Finding Mersenne primes in M[2..%d]:"%upb_prime));

print (" Finding Mersenne primes in M[2..%d]:"%upb_prime)

count=0;

count=0

for p in range(2, upb_prime+1): ~~# do~~

for p in range(2, upb_prime+1):

if is_prime(p) and is_mersenne_prime(p):

print("M%d"%p),

stdout.flush();

stdout.flush()

count += 1

fi;

if count >= upb_count: break

print</python>

od

print

Output:

Finding Mersenne primes in M[2..33218]:

<pre> 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

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</pre>

=={{header|Scheme}}==