Import the erf function as it is used to compute the partial χ².

pcigale/analysis_modules/pdf_analysis/utils.py

@@ -8,6 +8,7 @@
 from astropy import log
 from astropy.table import Table, Column
 import numpy as np
+from scipy.special import erf
 from scipy.stats import scoreatpercentile
 
 from ..utils import OUT_DIR