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Factors of a Mersenne number: Difference between revisions

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Factors of a Mersenne number (view source)

Revision as of 16:27, 2 May 2009

88 bytes removed ,  15 years ago
→‎[[Trial_factoring_of_a_Mersenne_number#ALGOL 68]]: link to "pow_mod.a68" prelude
m (oct...)
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{{trans|Fortran}}
 
{{works with|ALGOL 68|Standard - nowith extensionsprelude toinserted language usedmanually}}
{{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}}
<!-- {{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386}}
Compiles, but I couldn't maxint not in library, works with manually entered maxint, bits width. Leaving some issue with newline -->
<lang algol>PROC is prime = (INT number)BOOL:BEGIN▼
<pre>
▲PROC is prime = (INT number)BOOL:BEGIN
SKIP # code omitted - see Primality by Trial Division #
END;
 
MODE POWMODSTRUCT = INT;
PR READ "prelude/pow_mod.a68" PR;
 
PROC m factor = (INT p)INT:BEGIN
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SKIP
ELSE
n := 1pow mod(2,p,q);
FOR i FROM msb BY -1 TO 0 DO
IF ( BIN p SHR i AND 2r1 ) = 2r1 THEN
n := n*n*2 MOD q
ELSE
n := n*n MOD q
FI
OD;
IF n = 1 THEN
m factor := q;
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FI
 
END</lang>
</pre>
Example:
<pre>
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