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Rolf Eike Beer wrote: |
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> The previous algorithm would scan for all primes for a given number, |
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> which takes needlessly long. |
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Please also mention how this caused a problem for you in the commit |
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message, to help us understand why you're proposing to change this. |
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> +++ b/eclass/qmail.eclass |
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> -# @FUNCTION: is_prima |
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> +# @FUNCTION: is_prime |
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> # @USAGE: <number> |
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> # @DESCRIPTION: |
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> # Checks wether a number is a prime number |
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Maybe name the algorithm? Looks like an optimization of the sieve of |
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Eratosthenes? |
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> is_prime() { |
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> local number=${1} i |
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> - for i in $(primes ${number} ${number}) |
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> + |
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> + if [[ $[number % 2] == 0 ]]; then |
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> + return 1 |
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> + fi |
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While 2 itself is prime the above returns 1 for any even number. |
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> + for ((i = 3; i * i <= number; i += 2)) |
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> do |
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> - [[ ${i} == ${number} ]] && return 0 |
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> + if [[ $[number % i ] == 0 ]]; then |
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An inconsistent space after "% i" here. I don't know what style is correct. |
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//Peter |
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