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- - C Prime (http://www.programmingforums.org/showthread.php?t=1121)

lostcauz

Nov 12th, 2004 6:35 PM

here's the slightly improved c code.

/*straight c code .00192 sec. number tested 111111113*/

/* .00449 sec alt test number tested 654159511*/

int is_prime2(int n){ 

  int i,k;

  

  if (n<=3)return 1; 

  if(n&1==0)return 0;

  k=sqrt(n)+1;



  for (i=3;i<=k;i+=2){

   if(n%i==0)return 0;

  }

  return 1;

}

lostcauz

Nov 12th, 2004 10:37 PM

Now the pointer contains roughly the square root of the number we are testing for prime. We will now *blaze* to the result. :rock:

kurifu

Nov 12th, 2004 11:07 PM

So curiously, what C/C++ code did you compare this execution too? I suspect that one would be able to match the speed of execution without having to break down into an inline assembly at all.

lostcauz

Nov 12th, 2004 11:24 PM

The C code was listed in the first post as was this statement.

Quote:

Obviously the C code could have been further optimized before the comparison.

I was simply recanting an experience for those that might be interested. Even the assembly code here is still not the best and I've seen a better algorithm already. This was just for my fun. You are welcome to optimize either or both of them if you wish. ;)

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