Primality by trial division: Difference between revisions

=={{header|SNOBOL4}}==

<lang SNOBOL4>define('isprime(n)i,max') :(isprime_end)

isprime isprime = n; max = chop(sqrt(n)); i = 1

le(n,1) :s(freturn)

le(n,3) :s(return)

eq(remdr(n,2),0) :s(freturn)

isp1 i = le(i + 2,max) i + 2 :f(return)

eq(remdr(n,i),0) :s(freturn)f(isp1)

isprime_end</lang>

===By Patterns===

Using the Abigail regex transated to Snobol patterns.

<lang SNOBOL4> define('rprime(n)str,pat1,pat2,m1') :(end_rprime)

rprime str = dupl('1',n); rprime = n

pat1 = ('1' | '')

pat2 = ('11' arbno('1')) $ m1 (*m1 arbno(*m1))

str pos(0) (pat1 | pat2) rpos(0) :s(freturn)f(return)

end_rprime

* # Test and display primes 0 .. 50

loop rprimes = rprimes rprime(n) ' '

n = lt(n,50) n + 1 :s(loop)

output = rprimes

end</lang>

Output:

<pre>2 3 5 7 11 13 17 19 23 29 31 37 41 43 47</pre>