Error correlations for MATISSE (left column) and DEGAS (right column) for spectra with SNR ~ 20. The colour code, which corresponds to the metallicity, is the same as in Fig. 2. The general shape of these figures shows the degeneracy between the atmospheric parameters. For higher SNRs the correlation slopes are similar, but less extended, because the errors are smaller. The specific properties of each analysis method lead to the somewhat different extension and dispersion of the correlations.