Add block diagram.

libraries/base/common/python/try_round_weight.py

@@ -65,7 +65,26 @@ import matplotlib.pyplot as plt
 # Parse arguments to derive user parameters
 _parser = argparse.ArgumentParser(
     description="".join(textwrap.dedent("""\
-        Model effect of applying a weight after or before rounding:
+        Model effect of applying a weight on input noise after or before rounding,
+        for range of input noise sigma and range of weights:
+
+                 sigma
+                   |      2**resolution       1/2**resolution
+                   |       |                   |
+                   v       v                   v
+                 -----   -----   ---------   -----  noise_q   -----   ---------   -------
+        noise -->| X |-->| X |-->| round |-->| X |----------->| X |-->| round |-->| std |--> sigma_qq
+                 ----- | -----   ---------   -----            -----   ---------   -------
+                       |                                        ^
+                       |                                        |
+                       |                            weight ---->|
+                       |                                        |
+                       |                            noise_s   -----   ---------   -------
+                       |------------------------------------->| X |-->| round |-->| std |--> sigma_sq
+                                                              -----   ---------   -------
+
+        sigmas_ratio_qq_sq = sigma_qq / sigma_sq --> shows jumps and variation around 1 when resolution is low
+        sigmas_ratio_sq_input = sigma_sq / sigma --> shows that rounding causes change in sigma
 
         . weights in range(w_lo, w_hi, w_step)
         . sigma of noise in range(s_lo, s_hi, s_step)