Upon running with 'resume', Ultranest terminates the run with the message 'No changes made. Probably the strategy was to explore in the remainder, but it is irrelevant already; try decreasing frac_remain.'

[garvitagarwal290]

• UltraNest version: 3.4.6
• Python version: 3.9.7
• Operating System: Rocky Linux 8.5 (Green Obsidian)

Description

I have time series data, and I am fitting them using models of 9 and 15 parameters. The fitting works okay for most of the data, but at the same time, for a large portion of them, the fitting runs for 96 hours, at which point it hits the wall-time of the HPC that I am using. Then I rerun the fitting of these time series using the 'resume' feature. The program runs for about 10 minutes, but then it terminates (with Exit_status = 0), and the final output of the run looks like the following.

[ultranest] Likelihood function evaluations: 428273387
[ultranest] Writing samples and results to disk ...
[ultranest] Writing samples and results to disk ... done
[ultranest] No changes made. Probably the strategy was to explore in the remainder, but it is irrelevant already; try decreasing frac_remain.
[ultranest] done iterating.

logZ = -21590.640 +- 1.022
  single instance: logZ = -21590.640 +- 0.235
  bootstrapped   : logZ = -21602.796 +- 0.751
  tail           : logZ = +- 0.693
insert order U test : converged: True correlation: inf iterations

    per_bary            : 56.131191572319658│                   ▇                   │57.231191572319652    56.681191572319669 +- 0.000000000000014
    a_bary              : 44.586│                   ▇                   │45.686    45.136 +- 0.000
    r_planet            : 0.065 │                   ▇                   │0.183     0.125 +- 0.000
    b_bary              : 0.000001000000000000│         ▇                             │0.731980832173530938    0.181980832173530810 +- 0.000000000000000056
    ecc_bary            : 0.073 │                       ▇               │1.000     0.623 +- 0.000
    w_bary              : 331.093│                   ▇                   │332.193    331.643 +- 0.000
    t0_bary_offset      : -0.050│                   ▇                   │0.050     -0.001 +- 0.000
    M_planet            305550513862216355811887677440 +- 35184372088832
    r_moon              : 0.000000123800000000│                      ▇                │0.123799876200000006    0.069941430543806068 +- 0.000000000000000014
    per_moon            : 0.612 │                   ▇                   │1.712     1.162 +- 0.000
    tau_moon            : 0.0000010000000000000│   ▇                                   │0.5984283447503323528    0.0484283447503322806 +- 0.0000000000000000069
    Omega_moon          : 211.584305462244203│                   ▇                   │212.684305462244225    212.134305462244271 +- 0.000000000000057
    i_moon              : 96.861177229315487│                   ▇                   │97.961177229315510    97.411177229315484 +- 0.000000000000014
    M_moon              577461808577478822312542208 +- 343597383680
    q1                  : 0.084 │                       ▇               │1.000     0.634 +- 0.000
    q2                  : 0.0000010000000000000│  ▇                                    │0.5840102855886486477    0.0340102855886486102 +- 0.0000000000000000069

I just wanted to understand the meaning of this. Does this mean that the fitting has already converged, and I can use the model parameter estimates? If yes, then why did the program keep running for 96 hours? If no, then how can I avoid this situation? By decreasing frac_remain as suggested in the output above?

PS: This doesn't happen every time I use the resume feature. In many cases, the fitting resumes okay, runs for several hours, and terminates successfully and normally.