MATLAB Central Newsreader - print prime

print prime

John Wong — Thu, 24 Sep 2009 12:23:03 -0400

I wrote a program, but this is so buggy I guess?
I have this P4 2.6Ghz pc & 1GB Ram, I guess it's running out of memory or something.

Some numbers it will print not a prime / is a prime.

Let say primeTest(1)
it will say it's a prime

but when you do like primeTest(10)
nothing shows instead, on the bottom of the matlab (where the start menu is located), it will say "busy".

is there something i misunderstood my own program?

function primeTest(x)
n = 3;
R=rem(x,n);
while R ~= 0 & n < sqrt(x) & n < 10
    n+2;
    r=rem(x,n);
end
if R ~= 0
    disp('Is a prime')
else
    disp('Not a prime')

end
end

Re: print prime

Aurelien Queffurust — Thu, 01 Oct 2009 14:19:03 -0400

"John Wong" <gokoproject@gmail.com> wrote in message <h9fob7$hs7$1@fred.mathworks.com>...
> I wrote a program, but this is so buggy I guess?
> I have this P4 2.6Ghz pc & 1GB Ram, I guess it's running out of memory or something.
>
> Some numbers it will print not a prime / is a prime.
>
> Let say primeTest(1)
> it will say it's a prime
>
> but when you do like primeTest(10)
> nothing shows instead, on the bottom of the matlab (where the start menu is located), it will say "busy".
>
> is there something i misunderstood my own program?
>
>
> function primeTest(x)
> n = 3;
> R=rem(x,n);
> while R ~= 0 & n < sqrt(x) & n < 10
> n+2;
> r=rem(x,n);
> end
> if R ~= 0
> disp('Is a prime')
> else
> disp('Not a prime')
>
> end
> end

In your while loop your forget to assign n+2 to n which explains why you stay in thsi while loop and MATLAB stays busy:
replace n+2 by n = n+2

Re: print prime

us — Thu, 01 Oct 2009 14:30:21 -0400