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Prime number or its nearest prime numbers

Asked by Rahul Singh on 13 Apr 2012

anyone please tell me in matlab how to write a function to find prime number of any number if it is not prime number then function show its nearest prime numbers... let take example ...take number 9 we know it is not prime then the program will show its nearest prime like 7 and 11..

2 Comments

Thomas on 13 Apr 2012

if this is homework, can you show, what you have done so far?

Jan Simon on 13 Apr 2012

What have you tried so far and which problem occurred?

Rahul Singh

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2 Answers

Answer by Andrei Bobrov on 13 Apr 2012
Accepted answer

input x

x = 24;

solution

X = [x x];
out = zeros(1,2);
while 1
   t = isprime(X);
   if all(t)
       out = X;
       break
   elseif any(t)
       out(t) = X(t);
       t1 = ~t;
       X(t1) = X(t1) - sum([1 -1].*t1);
   else
       X = X - [1 -1];
   end
end
out = unique(X)

2 Comments

Jan Simon on 13 Apr 2012

I assume, this is the solution of Rahul's homework, Andrei.

Rahul Singh on 14 Apr 2012

thanks Andrei Bobrov........i think this is useful answer for me............

Andrei Bobrov
Answer by Sean de Wolski on 13 Apr 2012

isprime() will be your friend.

0 Comments

Sean de Wolski

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