Gottfried Barthel on Wed, 24 Jul 2002 16:27:59 +0200 (MET DST)

 Strange loop in factorint/ECM ?

```Hello Pari users,

I came across a strange problem and don't know what to do. I am trying to
factor the following composed integer with 98 digits using factorint :

6204279888025911871492956512013727029580743831970370591158040237796021\
9673213931222368764555941101

Rho/SQUFOF did not find any "cheap" factor. Then factorint entered the ECM
phase with the message

IFAC: trying Lenstra-Montgomery ECM
ECM: working on 64 curves at a time; initializing for up to 50 rounds...
ECM: time =      0 ms
ECM: dsn = 12,  B1 = 1800,      B2 = 198000,    gss =  128*420
ECM: time =  68920 ms, B1 phase done, p = 1801, setting up for B2
ECM: time =   1210 ms, entering B2 phase, p = 2017
ECM: time =  42990 ms

and continued for quite a while, but now it seems sort of stuck in a loop
since it has consecutively issued the same values

dsn = 72,  B1 = 1073500,   B2 = 118085000, gss = 1024*420 :

three times:
...
ECM: dsn = 68,  B1 = 679500,    B2 = 74745000,  gss = 1024*420
ECM: time = 21533840 ms, B1 phase done, p = 679501, setting up for B2
ECM: time =   1490 ms, entering B2 phase, p = 679723
ECM: time = 17676690 ms
ECM: dsn = 70,  B1 = 854100,    B2 = 93951000,  gss = 1024*420
ECM: time = 26971580 ms, B1 phase done, p = 854111, setting up for B2
ECM: time =   1440 ms, entering B2 phase, p = 854327
ECM: time = 22224380 ms
ECM: dsn = 72,  B1 = 1073500,   B2 = 118085000, gss = 1024*420
ECM: time = 33967410 ms, B1 phase done, p = 1073507, setting up for B2
ECM: time =   1440 ms, entering B2 phase, p = 1073717
ECM: time = 27838470 ms
ECM: dsn = 72,  B1 = 1073500,   B2 = 118085000, gss = 1024*420
ECM: time = 33682580 ms, B1 phase done, p = 1073507, setting up for B2
ECM: time =   1430 ms, entering B2 phase, p = 1073717
ECM: time = 27518310 ms
ECM: dsn = 72,  B1 = 1073500,   B2 = 118085000, gss = 1024*420

I am using Pari 2.1.14 on a SUN Ultra:

GP/PARI CALCULATOR Version 2.1.4 (released)
UltraSparc (MicroSparc kernel) 32-bit version
(readline v2.2 enabled, extended help available)

Copyright (C) 2002 The PARI Group

Any hint what to do?

By the way, could someone explain to me the meaning of the output? I did
not find any documentation in the User's guide. I understand that B1 and
B2 should be the bounds in the present ECM round, but what is the meaning
of dsn, gss, and p ?

Thanks in advance and best regards from Konstanz,

Gottfried Barthel

PS: Since I am new to this list, I am not sure if such a technical
question should rather have been addressed to the dev list. I hope that
the right people will read my message ...
```