I should maybe also (re-)mention that if you don't want to search for a fixed time, you can use the -psearch option with either min,avg, or good as a qualifier. yafu will stop when it finds a {min,avg,good} poly for the input number.

min,avg,good are chosen based on

Batalov's heuristic.

-psearch min --> uses a multiplier of 1 to that fit

-psearch avg --> uses a multipler of 1.036

-psearch good --> uses a multiplier of 1.072

Just now, with that c120, I found a "min" poly of score = 2.937000e-010 in 3 minutes (8 threads), after searching a range of only a thousand coefficients or so. That actually just barely missed being qualified "avg".

On the start of the job the heuristic said the following, so the poly fits in the range expected:

nfs: expecting degree 5 poly E from 2.87e-010 to > 3.30e-010

best poly:

# norm 2.039066e-011 alpha -6.282017 e 2.937e-010 rroots 5

n: 227010481295437363334259960947493668895875336466084780038173258247009162675779735389791151574049166747880487470296548479

skew: 95431.04

c0: -46602088970638410228907101375

c1: 643792960629014034531255

c2: 64059317395932803683

c3: 49937622929009

c4: -7589830536

c5: 9108

Y0: -120039626008868252603764

Y1: 93171618323