GreyHat64

Vessel Username: GreyHat64 Videos: https://www.vessel.com/videos/LCoY5zfFf https://www.vessel.com/videos/JYZEYDYx0

If I won, I'd be using the processor for content creation and visualization.

Great giveaway! I love the general overbuiltness of these cards.

Disregard this entry.

Very nice 1 million sub video. It's amazing to think that when I first started, the WAN Show was yet unnamed and in your garage, and now you've gone fully professional with a company of seven. Congratulations, I look forward to your future content and success.

Thanks to Darrin Lynch for joining us today.

Thanks again. All of my segfaults are fixed now, but the code is still not quite working. I'll be investigating it further from this point. This may be a stupid question, but what IDE or debugger is that? I've been using GDB and Valgrind.

Thanks for pointing out the misplaced free statements. That was part of the issue. Just to address your other points:1. There is no multiplication in the initialization of *primes because it is used as a dynamically growing array later in the code. 2. I can't just iterate down from sqrtConstant because that could give me composite factors that would have to be factored, creating some nasty recursion. 3. I used a long for sqrtConstant because it's guaranteed to be a 32-bit signed integer, while an int could be either 16-bit or 32-bit. 16-bits would be too small for sqrtConstant. Noted and fixed. Thanks!Now here's the new code: /* Program to compute the greatest prime factor of CONSTANT. Primes up to the * sqrt of CONSTANT are found using the sieve of Eratosthenes. Primes are then * used for trial division in descending order to find the greatest prime * factor. */#include <stdio.h>#include <stdlib.h>#include <math.h>#define CONSTANT 600851475143.0int main(void){ enum boolean { FALSE, TRUE }; long sqrtConstant = floor(sqrt(CONSTANT)); char *sieve = malloc((sqrtConstant+1) * sizeof(char)); /* Boolean array */ double *primes = malloc(sizeof(double)); /* Primes up to sqrt of const */ double *temp; int i = 0; /* Greatest index of primes */ long n; if (sieve == NULL || primes == NULL) { printf("Error allocating memory!\n"); return 1; }/* if (sieve == NULL) { printf("Error allocating memory! (sieve)\n"); return 1; } if (primes == NULL) { printf("Error allocating memory! (primes)\n"); return 1; }*/ for (n = 0; n <= sqrtConstant; n++) { /* Initialize the sieve */ if (n < 2) { sieve[n] = FALSE; } else { sieve[n] = TRUE; } } for (n = 2; n <= sqrtConstant; n++) { /* Sieve of Eratosthenes */ if (sieve[n] == TRUE) { long m; for (m = n * n; m <= sqrtConstant; m += n) { sieve[m] = FALSE; } } } for (n = 0; n <= sqrtConstant; n++) { /* Convert sieve to array of primes */ if (sieve[n] == TRUE) { primes[i] = n; temp = realloc(primes, ((i++)+2) * sizeof(double)); if (temp !=NULL) { primes = temp; } else { free(sieve); free(primes); printf("Error allocating memory!\n"); return 1; } } } free(temp); free(sieve); while (primes[i-1] != floor(primes[i-1])) { /* Determine greatest prime factor*/ /*segfault*/ i--; } printf("%.f\n", primes[i]); free(primes); return 0;}

I'm working on Project Euler as a coding exercise. The third problem asks what the greatest prime factor of a large arbitrary number is. Here's my code: /* ANSI C program to compute the greatest prime factor of CONSTANT. Primes up to the * sqrt of CONSTANT are found using the sieve of Eratosthenes. Primes are then * used for trial division in descending order to find the greatest prime * factor. */#include <stdio.h>#include <stdlib.h>#include <math.h>#define CONSTANT 600851475143.0int main(void){ enum boolean { FALSE, TRUE }; long sqrtConstant = floor(sqrt(CONSTANT)); char *sieve = malloc((sqrtConstant+1) * sizeof(char)); /* Boolean array */ double *primes = malloc(sizeof(double)); /* Primes up to sqrt of const */ double *temp; int i = 0; /* Greatest index of primes */ long n; if (sieve == NULL || primes == NULL) { printf("Error allocating memory!\n"); return 1; }/* if (sieve == NULL) { printf("Error allocating memory! (sieve)\n"); return 1; } if (primes == NULL) { printf("Error allocating memory! (primes)\n"); return 1; }*/ for (n = 0; n <= sqrtConstant; n++) { /* Initialize the sieve */ if (n < 2) { sieve[n] = FALSE; } else { sieve[n] = TRUE; } } for (n = 2; n <= sqrtConstant; n++) { /* Sieve of Eratosthenes */ if ((sieve[n] = TRUE)) { long m; for (m = n * n; m <= sqrtConstant; m += n) { sieve[m] = FALSE; } } } for (n = 0; n <= sqrtConstant; n++) { /* Convert sieve to array of primes */ if ((sieve[n] = TRUE)) { /* Segfault */ primes[i] = n; temp = realloc(primes, ((i++)+2) * sizeof(double)); if (temp !=NULL) { primes = temp; } else { free(primes); printf("Error allocating memory!\n"); return 1; } free(sieve); free(temp); } } while (primes[n] != floor(primes[n])) { /* Determine greatest prime factor*/ i--; } printf("%.f\n", primes[i]); free(primes); return 0;}I'm getting segfaults of all different sorts from my sieve array. Initially I was getting a stack overflow because the sieve was an array stored in the stack. It shouldn't have caused a stack overflow on my machine though, because it's only 775,147 bytes in size, smaller than my 8 MB stack limit. Either way, I decided to move the sieve into the heap by using a pointer instead of an array. Since then, I've been dealing with access and write related segfaults with the sieve. I can't figure out what the underlying issue is. Also, general criticism of my code would be appreciated.

I'd have to say that the build quality is the thing I like the most about the One.

My storage setup is a Crucial M4 128GB SSD as my boot drive and a Seagate Barracuda 1TB drive for games and video editing. I use the Crucial M4 because it's a low cost, reliable SSD with decent speed, and I use a Barracuda because it's a low cost 7200 RPM drive with 64MB of cache. I'd love to upgrade to a WD Red drive setup because I have many times filled my 1TB drive with raw video, and I want a redundant way to archive my videos.

My Steam library's a bit small. Could definitely use some games. :D https://twitter.com/greyhat2600

It does have SATA ports, I believe SATA II.

I'm thinking of finally setting up a small storage server for backups, torrents, etc. I have an old Dell with a Pentium 4 630 that I'm thinking of using, but I'm also very open to building a server or buying a prebuilt if it fits my budget better. I'm trying to do this for as little money as possible, while not skimping on features or performance. I'm thinking of a RAID 1 array of two 1 TB or 2 TB drives on the motherboard, as a RAID card is overkill and out of the price range. Thoughts and suggestions?

Yet another great giveaway! https://www.facebook.com/nhanley314/posts/555022621229826 https://twitter.com/greyhat2600