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42 lines
1.0 KiB
Plaintext
42 lines
1.0 KiB
Plaintext
NAME
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factor - smallest prime factor not exceeding specified limit
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SYNOPSIS
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factor(n [, limit [, err]])
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TYPES
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n integer
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limit integer with abs(limit) < 2^32, defaults to 2^32 - 1
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err integer
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return positive integer, -1 or err
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DESCRIPTION
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If n >= 0 and n has a prime factor less than or equal to limit,
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factor(n, limit) returns the smallest such factor. If n >= 0
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and the smallest prime factor of n exceeds limit, 1 is returned.
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In particular, if n >= 0 and limit <= 1, factor(n, limit)
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always returns 1; factor(n,2) returns 2 if and only if n is even.
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If n < 0, -1 is returned.
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If abs(limit) >= 2^32, factor(n, limit) causes an error,
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factor(n, limit, err) returns the value of err.
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EXAMPLE
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> print factor(35,4), factor(35,5), factor(35), factor(-35)
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1 5 5 -1
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> print factor(2^32 + 1), factor(2^47 - 1), factor(2^59 - 1)
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641 2351 179951
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LIMITS
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none
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LIBRARY
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FLAG zfactor(ZVALUE n, ZVALUE limit, ZVALUE *res)
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SEE ALSO
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lfactor
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