COBAYA: Issue with chains not converging
Posted: August 21 2024
Hello everyone, I was trying to make some cobaya runs to understand how the program works.
For example, I ran with the following .yaml file, which is taken from the cobaya input generator ( plus I removed the planck likelihood):
I ran this on a cluster with 4 MPI processes for 48 hours and the chains did not converge! (I had 150000 accepted steps).
The R-1 computed oscillated a lot and never decreased below a value of ~ 5.
Furthermore, the .progress file in the output is always empty and no progress regarding the convergence is written into it.
However progress can be seen from the standard cobaya output where I can see chains progressing and R-1 being computed.
I would like to understand if there is anything wrong with the way I'm setting up the run or any other issue.
Thank you!
For example, I ran with the following .yaml file, which is taken from the cobaya input generator ( plus I removed the planck likelihood):
Code: Select all
theory:
camb:
extra_args:
halofit_version: mead
bbn_predictor: PArthENoPE_880.2_standard.dat
lens_potential_accuracy: 1
num_massive_neutrinos: 1
nnu: 3.044
theta_H0_range:
- 20
- 100
likelihood:
bao.sixdf_2011_bao: null
bao.sdss_dr7_mgs: null
bao.sdss_dr12_consensus_bao: null
params:
logA:
prior:
min: 1.61
max: 3.91
ref:
dist: norm
loc: 3.05
scale: 0.001
proposal: 0.001
latex: \log(10^{10} A_\mathrm{s})
drop: true
As:
value: 'lambda logA: 1e-10*np.exp(logA)'
latex: A_\mathrm{s}
ns:
prior:
min: 0.8
max: 1.2
ref:
dist: norm
loc: 0.965
scale: 0.004
proposal: 0.002
latex: n_\mathrm{s}
theta_MC_100:
prior:
min: 0.5
max: 10
ref:
dist: norm
loc: 1.04109
scale: 0.0004
proposal: 0.0002
latex: 100\theta_\mathrm{MC}
drop: true
renames: theta
cosmomc_theta:
value: 'lambda theta_MC_100: 1.e-2*theta_MC_100'
derived: false
H0:
latex: H_0
min: 20
max: 100
ombh2:
prior:
min: 0.005
max: 0.1
ref:
dist: norm
loc: 0.0224
scale: 0.0001
proposal: 0.0001
latex: \Omega_\mathrm{b} h^2
omch2:
prior:
min: 0.001
max: 0.99
ref:
dist: norm
loc: 0.12
scale: 0.001
proposal: 0.0005
latex: \Omega_\mathrm{c} h^2
omegam:
latex: \Omega_\mathrm{m}
omegamh2:
derived: 'lambda omegam, H0: omegam*(H0/100)**2'
latex: \Omega_\mathrm{m} h^2
mnu: 0.06
omega_de:
latex: \Omega_\Lambda
YHe:
latex: Y_\mathrm{P}
Y_p:
latex: Y_P^\mathrm{BBN}
DHBBN:
derived: 'lambda DH: 10**5*DH'
latex: 10^5 \mathrm{D}/\mathrm{H}
tau:
prior:
min: 0.01
max: 0.8
ref:
dist: norm
loc: 0.055
scale: 0.006
proposal: 0.003
latex: \tau_\mathrm{reio}
zrei:
latex: z_\mathrm{re}
sigma8:
latex: \sigma_8
s8h5:
derived: 'lambda sigma8, H0: sigma8*(H0*1e-2)**(-0.5)'
latex: \sigma_8/h^{0.5}
s8omegamp5:
derived: 'lambda sigma8, omegam: sigma8*omegam**0.5'
latex: \sigma_8 \Omega_\mathrm{m}^{0.5}
s8omegamp25:
derived: 'lambda sigma8, omegam: sigma8*omegam**0.25'
latex: \sigma_8 \Omega_\mathrm{m}^{0.25}
A:
derived: 'lambda As: 1e9*As'
latex: 10^9 A_\mathrm{s}
clamp:
derived: 'lambda As, tau: 1e9*As*np.exp(-2*tau)'
latex: 10^9 A_\mathrm{s} e^{-2\tau}
age:
latex: '{\rm{Age}}/\mathrm{Gyr}'
rdrag:
latex: r_\mathrm{drag}
sampler:
mcmc:
drag: true
oversample_power: 0.4
proposal_scale: 1.9
covmat: auto
Rminus1_stop: 0.01
Rminus1_cl_stop: 0.2
output: output/bao_test
The R-1 computed oscillated a lot and never decreased below a value of ~ 5.
Furthermore, the .progress file in the output is always empty and no progress regarding the convergence is written into it.
However progress can be seen from the standard cobaya output where I can see chains progressing and R-1 being computed.
I would like to understand if there is anything wrong with the way I'm setting up the run or any other issue.
Thank you!