Mismatching ACCF CH4 Results

[trdean1]

I installed your library on my local machine and ran the test case listed in the main README.md file. All of my results matched the reference file (env_processed.nc), except the CH4 calculation and the merged ACCF results.

The following values are the maximum error between my computed values and the reference values (np.nanmax(abs(np.array(ds[key])-np.array(ds_ref[key])))).

pcfa: 0.0
aCCF_CH4: 1.399461059189977e-15
aCCF_O3: 0.0
aCCF_H2O: 0.0
aCCF_nCont: 0.0
aCCF_dCont: 0.0
aCCF_Cont: 0.0
aCCF_CO2: 0.0
aCCF_merged: 1.819426770702237e-17

Can you please advise if this is an issue with the installation on my local machine or a problem with your library?