Welcome to PrimeGrid Manual Sieving

This section of the forum is used to help coordinate the manual sieving efforts for non-boinc (manual) subprojects. The reservations for manual sieving efforts are now being managed through primegrid, as are the factor file uploads. Visit http://www.primegrid.com/show_sieving.php to make reservations and view your current reservations.

There's more instructions on a webpage written by Jim on using the manual sieving reservation system here: http://www.primegrid.com/sieving_intro.php

Current CPU Sieves:
• No current CPU sieves


Current GPU Sieves:

• GFN Sieve


FAQ:

• What exactly is sieving? Why is it used?
A sieve, in general, separates valuable materials from useless or unwanted materials.
In the terms of PrimeGrid, the sieving term refers to removing composite numbers from prime numbers. A sieve program can achieve this by eliminating numbers with small factors. This can be done a lot faster than primality testing (using LLR), therefore, we thoroughly sieve a data set before testing the remaining numbers for primality using LLR.

• Why not sieve the entire data set?
Using a sieve can eliminate many candidates from a set at first by eliminating those with small factors. However, as the sieve goes deeper, the sieve takes longer and longer to remove candidates. Eventually, the rate of removing candidates is the same rate as primality testing them with LLR.

• Can I earn BOINC credit by sieving?
YES! Even though it is not done though the BOINC client, you still get BOINC credit from completing manual sieving work. The credit you get from completing manual sieving is added to your queue after you upload your factor file and it is approved by an administrator. Then, every night around midnight, credit is added to your total. The amount of credit granted each night is approximately 80% of your current RAC. This process continues nightly until all of your pending credit has been granted.

Exactly how many credits can I get from manual sieving?

Listed below are the current PSA credit rates for manual sieving. Where more than one rate is listed (GFN, GCW), it's because the different n's or b's sieve at different speeds, and therefore have different rates. Slower sieves get more credit per amount sieved so that you get approximately the same credit per hour regardless of which n (GFN) or b (GCW) you're sieving.

Different sieves rates are listed as per G, per T, or per P, according to the size used to reserve sieving ranges.


GFN:
n=18: 10600 per P (Suspended)
n=19: 4730 per P
n=20: 4450 per P (Suspended)
n=21: 4320 per P (Suspended)
n=22: 4220 per P

PPR
700,000 per T (Suspended)

GCW:
b=13: 230,000 per T (Suspended)
b=25: 280,000 per T (Suspended)
b=29: 212,500 per T (Suspended)
b=41: 210,000 per T (Suspended)
b=47: 223,000 per T (Suspended)
b=49: 254,250 per T (Suspended)
b=53: 227,750 per T (Suspended)
b=55: 305,400 per T (Suspended)
b=69: 367,200 per T (Suspended)
b=73: 221,650 per T (Suspended)
b=79: 110,000 per T (Suspended)
b=101: 100,000 per T (Suspended)
b=109: 100,000 per T (Suspended)
b=116: 260,000 per T (Suspended)
b=121: 120,000 per T (Suspended)

SR5
100 per G (Suspended)

Factorial:
5500 per G (Suspended)

Primorial:
3700 per G (Suspended)

• What do the terms "p" and "P" and "T" and "G" mean ?
A common notation used in sieving is: p | k*b^n+-1
Here's an example using a recent factor submission for PSP sieve:
7266111922899983 | 79817*2^45327351+1
p=7266111922899983
k=79817
b=2
n=45327351

This means that 7266111922899983 is a factor of 79817*2^45327351+1. Therefore, 79817*2^45327351+1 is not prime and does not have to be primality tested (LLR). 79817*2^45327351+1 will be removed from the possible prime candidates.

P is the symbol used for peta (10^15 or 1,000,000,000,000,000)
T is the symbol used for tera (10^12 or 1,000,000,000,000)
G is the symbol used for giga (10^9 or 1,000,000,000)

The factors are so large that we refer to them in P or T or G. The factor above would be in the 7.2P to 7.3P range or 7200T to 7300T range or 7200000G to 7300000G. Please see SI prefixes for more information the International System of Units.

Primorial Prime Search Sieving

Primorial Sieving is not currently active


The Primorial sieve supports the Primorial Prime Search. Below are instructions on how to participate in this manual effort.

1. We are using the fpsieve program which is a combination of fsieve and psieve both developed by Mark Rodenkirch. Thanks to Geoff Reynolds for combing them.

2. After you reserve a range at http://www.primegrid.com/show_sieving.php, it will show you what commands to run and what programs to download for your sieving.

Note: If you are doing using the -t switch on your sieve instead of doing one process for each range, it is a little LESS productive (1%-2%), but it's easier to manage.


3. Let it run to completion. If you need to stop the program for any reason, just hit ctrl-c. It will create a checkpoint.txt file so it will resume where it left off.
4. Once completed, visit the http://www.primegrid.com/show_sieving.php page, select upload next to your sieve reservation, browse your computer for the factor file and select upload.

Congratulations! You have successfully contributed to the Primorial Sieving effort.

Factorial Prime Search Sieving


Factorial Sieving is not currently active


The Factorial sieve supports the Primorial Prime Search. Below are instructions on how to participate in this manual effort.

1. We are using the fpsieve program which is a combination of fsieve and psieve both developed by Mark Rodenkirch. Thanks to Geoff Reynolds for combing them.

2. After you reserve a range at http://www.primegrid.com/show_sieving.php, it will show you what commands to run and what programs to download for your sieving.

Note: If you are doing using the -t switch on your sieve instead of doing one process for each range, it is a little LESS productive (1%-2%), but it's easier to manage.


3. Let it run to completion. If you need to stop the program for any reason, just hit ctrl-c. It will create a checkpoint.txt file so it will resume where it left off.
4. Once completed, visit the http://www.primegrid.com/show_sieving.php page, select upload next to your sieve reservation, browse your computer for the factor file and select upload.

Congratulations! You have successfully contributed to the Factorial Sieving effort.

GFN Prime Search Sieving

This sieve supports the GFN Prime Search located on BOINC.


Sieving is active for the following:

N = 524288 (2^19)
N = 4194304 (2^22)

This sieve uses axn's GFNSvCUDA sieve program (currently available only for Windows 64 bit and nVidia GPU). It is command-line based and the process is straight forward. Reservations are open via the Primegrid Manual Sieving page at http://www.primegrid.com/show_sieving.php.

After you reserve a range, you are sent to the instructions page where it will guide you through the command line switches and where to download the executables.

The effort at N = 4194304 has the potential to produce the World's Largest Prime (via the GFN "Do You Feel Lucky" project)

Generalized Cullen/Woodall Prime Search Sieving


GCW Sieving was moved to BOINC, and closed on May 1st, 2019.


This sieve supports the GCW Prime Search located on BOINC.

The following bases are open for sieving for n=1M-2M:
None

The following bases have been suspended:
b=13, 25, 29, 41, 47, 49, 53, 55, 69, 73, 79, 101, 109, 116, 121

This sieve uses the gcwsieve program developed by Geoff Reynolds. Reservations and instructions are handled by the Primegrid manual sieving page at http://www.primegrid.com/show_sieving.php.

Reservations may be made at the manual sieving page. PSA credit is available.