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primes function

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Sean Smith
Sean Smith 2011-9-18
编辑： Walter Roberson 2017-1-31
Is there a way to use the prime function to find the prime numbers between two numbers? I want to find the prime numbers between 20,000 and 10,000 and save that to a variable. primes(20000) gives me them all the way to zero and if i try to subtract primes(20000) and primes(10000) it won't let me because there not the same size. Any ideas? Thanks.
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Jack Garvey
Jack Garvey 2017-1-31
编辑：Walter Roberson 2017-1-31
1.) make array of range: range = [10000:1:20000]
2.) create logical array of (range) displaying which numbers are prime: isprime(range)
3.) find total amount of prime numbers within that range: number_of_primes = sum(isprime(range))
4.) i got the answer of 1033 prime numbers between 10K and 20K

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采纳的回答

Walter Roberson
Walter Roberson 2011-9-18
setdiff(primes(20000),primes(10000))

更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2011-9-18
k = 1e4:2e4;
out = k(isprime(k));
variant
prms = primes(20000);
out = prms(prms>=10000);

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