Programming Forums > Application Development > C++

lostcauz · Nov 12th, 2004, 5:35 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, 9:37 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, 10:07 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, 10:24 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.

Nov 12th, 2004, 5:35 PM	#1
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	here's the slightly improved c code. (Toggle Plain Text) /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; } /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 Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Nov 12th, 2004, 9:37 PM	#2
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	Now the pointer contains roughly the square root of the number we are testing for prime. We will now blaze to the result. :rock: __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Nov 12th, 2004, 10:07 PM	#3
kurifu Expert Programmer Join Date: Jul 2004 Location: Halifax, Nova Scotia (Canada) Posts: 784 Rep Power: 5	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. __________________ Clifford Matthew Roche <geek@cliffordroche.com> Web Hosting: http://www.crd-hosting.com Consulting: http://www.crdev-consulting.com

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Programming Forums > Application Development > C++

C Prime