Updated explanation

binarycpython/utils/grid_options_defaults.py

@@ -606,12 +606,18 @@ e.g. [1,0,0,0] for single stars only
 defaults to [1,1,0,0] i.e. singles and binaries
 """,
     "normalize_multiplicities": """
-given a mix of multiplities, you can either (noting that
-here (S,B,T,Q) = appropriate modulator * model(S,B,T,Q) )
-
-'norm'  : normalize so the whole population is 1.0
-          after implementing the appropriate fractions
-          S/(S+B+T+Q), B/(S+B+T+Q), T/(S+B+T+Q), Q/(S+B+T+Q)
+'norm': normalize so the whole population is 1.0
+        after implementing the appropriate fractions
+        S/(S+B+T+Q), B/(S+B+T+Q), T/(S+B+T+Q), Q/(S+B+T+Q)
+        given a mix of multiplities, you can either (noting that
+        here (S,B,T,Q) = appropriate modulator * model(S,B,T,Q) )
+        note: if you only set one multiplicity_modulator
+        to 1, and all the others to 0, then normalizing
+        will mean that you effectively have the same number
+        of stars as single, binary, triple or quad (whichever
+        is non-zero) i.e. the multiplicity fraction is ignored.
+        This is probably not useful except for
+        testing purposes or comparing to old grids.
 
 'raw'   : stick to what is predicted, i.e.
           S/(S+B+T+Q), B/(S+B+T+Q), T/(S+B+T+Q), Q/(S+B+T+Q)
@@ -625,19 +631,12 @@ here (S,B,T,Q) = appropriate modulator * model(S,B,T,Q) )
           ...
           *** this is canonical binary population synthesis ***
 
+          It only takes the maximum multiplicity into account,
+          i.e. it doesn't multiply the resulting array by the multiplicity modulator again.
+          This prevents the resulting array to always be 1 if only 1 multiplicity modulator element is nonzero
+
           Note: if multiplicity_modulator == [1,1,1,1] this
                 option does nothing (equivalent to 'raw').
-
-Note: If you only set one multiplicity modulator to 1, and all others to zero,
-we will not multiply the fractions by the modulator. The grid will run fine (i.e. it will only run e.g. singles), but it will still take into account the real fraction
-This is unlike how this setting was previously implemented: normalizing
-will mean that you effectively have the same number
-of stars as single, binary, triple or quad (whichever
-is non-zero) i.e. the multiplicity fraction is ignored.
-
-
-
-
 """,
     "q_low_extrapolation_method": """
 q extrapolation (below 0.15) method