## A possible bug in Planck 2018 lensing likelihood

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
He Jia
Posts: 3
Joined: March 19 2019
Affiliation: Peking University / UC Berkeley

### A possible bug in Planck 2018 lensing likelihood

Hi,

I was trying to use the python interface of Planck 2018 lensing likelihood "smicadx12_Dec5_ftl_mv2_ndclpp_p_teb_consext8_CMBmarged", but I encountered a CError,

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<class 'str'>: (<class 'TypeError'>, TypeError('__str__ returned non-string (type bytes)',))
which was traced back to "self.get_clcmb_fid()". If I understand correctly, the issue is in ll. 79-83 of "src/python/clik/lkl_lensing.pyx":

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if apars.shape[0] == self.pdim:
qpars = nm.concatenate((apars[:lmax[0]+1],self.get_cltt_fid(),apars[nm.sum(lmax[1:]+1):]))
pars_proxy=nm.PyArray_ContiguousFromAny(qpars,nm.NPY_DOUBLE,1,1)
else:
pars_proxy=nm.PyArray_ContiguousFromAny(apars,nm.NPY_DOUBLE,1,1)
According to the Planck 2018 lensing paper, in the 2015 version the CMB spectrum is fixed for lensing-only likelihood, but in the 2018 version the CMB part is completely marginalized out. It seems that Planck people forgot to modify the code here, so the program was trying to load the fiducial CMB spectrum via "self.get_clcmb_fid()", which does not exist in the "cl_fid" file.

I tried to change those lines to the following, and then it worked well on my side:

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pars_proxy=nm.PyArray_ContiguousFromAny(apars,nm.NPY_DOUBLE,1,1)

Antony Lewis
Posts: 1652
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

### Re: A possible bug in Planck 2018 lensing likelihood

Thanks, could well be. Cobaya and CosmoMC also have native versions of the lensing likelihoods that do not need clik.

Alex Hall
Posts: 5
Joined: March 25 2012
Affiliation: Institute for Astronomy, Edinburgh, UK

### Re: A possible bug in Planck 2018 lensing likelihood

I find the same bug. The above modification seems to have fixed it!