Discussion related to cado-nfs

[Bill Winslow <bunslow@gmail.com>]

Hello everyone.

I am Dubslow from http://mersenneforum.org, and I've just downloaded CADO for the first time to try out its polyselect capabilities on a C195 from aliquot sequence 4788. The general consensus around MersenneForum is that all stages of CADO-NFS are marginally inferior to msieve/ggnfs, with the notable exception of the GNFS polynomial selection.

For most large GNFS tasks these days, the folks over at MF tend to use GPU-enabled Msieve polyselect, which despite an inferior algorithm, benefits from the ~100x speedup of GPUs. As I (and at least one other) don't have CUDA installed, I'd like to play around with CADO's polyselect.

I've done what I think is reasonable efforts to read all the documentation, but so far I've been unable to find out how to get the scripts to not even think about sieving/post-processing in the slightest. My parameters file has the following (polyselect params copied from the C190 example, save for I):

tasks.factorbase.run = false

tasks.sieve.run = false

tasks.filter.run = false

tasks.linalg.run = false

tasks.sqrt.run = false

tasks.polyselect.degree = 5

tasks.polyselect.P = 10000000

tasks.polyselect.admax = 5e7

tasks.polyselect.adrange = 5e5

tasks.polyselect.incr = 60

tasks.polyselect.nq = 1000

tasks.polyselect.nrkeep = 1000

tasks.I = 15

And yet, despite my best efforts, I get the following error when I launch cado-nfs.py:

Info:HTTP server: Using non-threaded HTTPS server

Debug:Generate Factor Base: Enter Task.__init__(factorbase)

Debug:Generate Factor Base: state = {}

Critical:Parameters: Required parameter alim not found under path tasks.sieve.factorbase

Traceback (most recent call last):

  File "../cado-nfs.py", line 102, in <module>

    path_prefix = [])

  File "../scripts/cadofactor/cadotask.py", line 5105, in __init__

    path_prefix=sievepath)

  File "../scripts/cadofactor/cadotask.py", line 2387, in __init__

    path_prefix=path_prefix)

  File "../scripts/cadofactor/cadotask.py", line 987, in __init__

    self.params = self.parameters.myparams(self.paramnames)

  File "../scripts/cadofactor/cadoparams.py", line 746, in myparams

    return self.parameters.myparams(keys, path)

  File "../scripts/cadofactor/cadoparams.py", line 169, in myparams

    self._convert_types(result, keys, splitpath, found_at_path)

  File "../scripts/cadofactor/cadoparams.py", line 584, in _convert_types

    raise KeyError(msg)

KeyError: 'Required parameter alim not found under path tasks.sieve.factorbase'

Why does cado-nfs insist on thinking about factorbase and sieving parameters when I will be doing nothing of the sort? In Msieve/Yafu I can select polyselect only with some variant of -np, -np1, -nps, -npr, and it doesn't require nor produce any sieving parameters whatsoever.

I'm reasonably certain that I could do just fine with some made up sieve parameters, but it still seems to me that I should be able to run individual parts of the overall algorithm without thinking about parts I know I won't be doing.

Of course there's a decent chance I've overlooked something, but a minor inquiry over at MF yielded nothing similar: http://mersenneforum.org/showthread.php?p=429303#post429303

Thank you for your consideration and assistance.

Bill