25 lines
1.9 KiB
Rexx
25 lines
1.9 KiB
Rexx
/*REXX program calculates the totient numbers for a range of numbers, and count primes. */
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parse arg N . /*obtain optional argument from the CL.*/
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if N=='' | N=="," then N= 25 /*Not specified? Then use the default.*/
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tell= N>0 /*N positive>? Then display them all. */
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N= abs(N) /*use the absolute value of N for loop.*/
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w= length(N) /*W: is used in aligning the output. */
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primes= 0 /*the number of primes found (so far).*/
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/*if N was negative, only count primes.*/
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do j=1 for N; T= phi(j) /*obtain totient number for a number. */
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prime= word('(prime)', 1 + (T \== j-1 ) ) /*determine if J is a prime number. */
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if prime\=='' then primes= primes + 1 /*if a prime, then bump the prime count*/
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if tell then say 'totient number for ' right(j, w) " ──► " right(T, w) ' ' prime
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end /*j*/
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say
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say right(primes, w) ' primes detected for numbers up to and including ' N
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exit 0 /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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phi: procedure; parse arg z; if z==1 then return 1
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#= 1
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do m=2 for z-2; parse value m z with x y
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do until y==0; parse value x//y y with y x
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end /*until*/
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if x==1 then #= # + 1
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end /*m*/
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return #
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