SNFS of C112 cofactor of 608^60+480^76

[WMHalsdorf]

Originally Posted by sean

I've been trying to complete 608^60+480^76 by SNFS using yafu. I first took out the obvious 2^300, then generated a degree 5 polynomial from (19^12)^5+15(2^16 * 5^75)^5. There is also a small factor 193. My input looks like:

n: 1512787865815604665168125992005458173124947471321097315052908880093889444629900995273034048975712989271411140657
m: 938653510572529699833798948683334366050403278236720135828886826556700342961769485489321955075594682751310365305
deg: 5
skew: 1.718
type: snfs
c5: 1
c0: 15
Y0: -2213314919066161
Y1: 28697814000000000000000
rlim: 588500
alim: 588500
lpbr: 25
lpba: 25
mfbr: 47
mfba: 47
rlambda: 2.3
alambda: 2.3

When I run yafu, sieving appears to proceed well with good yield etc. Yet when it gets to filtering things go awry, the nfs.log is full of messages like

Wed May 17 20:14:24 2017  error -11 reading relation 0
Wed May 17 20:14:24 2017  error -11 reading relation 1
Wed May 17 20:14:24 2017  error -11 reading relation 2
...

My first thought was that there must have been some corruption of files left over from a previous run. So I repeated the whole thing in a clean directory and the same thing happened. It only takes half an hour or so do the sieving. My next suspicion is that there is something wrong with my polynomials. Any ideas?

After removng the common factor 32^60 from both terms you end up with
19^60+480^16*15^60 which is
291968058102411700377448316457053427413114861964971781805211413858120662813570892087695571452312606929382350146801