add error margins to the plot of the oneshot bench commit (dragoon/komodo!83)

we see that the Arkworks / Komodo versions of the same curves are basically the same.
![Figure_1](/uploads/faa1523bbd3037390eb0c56f037995ea/Figure_1.png)

benches/README.md

@@ -96,11 +96,12 @@ these are benchmarks that run a single measurement, implemented as _examples_ in
 ### commit
 ```nushell
 let degrees = seq 0 15 | each { 2 ** $in }
-let res = cargo run --example bench_commit -- --nb-measurements 1 ...$degrees
+let res = cargo run --example bench_commit -- --nb-measurements 10 ...$degrees
     | lines
     | each { from nuon }
     | update times { into duration }
-    | insert t {|it| $it.times | math avg}
+    | insert mean {|it| $it.times | math avg}
+    | insert stddev {|it| $it.times | into int | into float | math stddev | into int | into duration}
 
 python scripts/plot/bench_commit.py (
     $res | group-by curve --to-table | update items { reject curve } | to json

scripts/plot/bench_commit.py

@@ -11,10 +11,15 @@ if __name__ == "__main__":
 
     for group in data:
         xs = [x["degree"] for x in group["items"]]
-        ys = [x["t"] / NB_NS_IN_MS for x in group["items"]]
+        ys = [x["mean"] / NB_NS_IN_MS for x in group["items"]]
+        zs = [x["stddev"] / NB_NS_IN_MS for x in group["items"]]
+
+        down = [y - z for (y, z) in  zip(ys, zs)]
+        up = [y + z for (y, z) in zip(ys, zs)]
 
         style = "dashed" if group["group"].endswith("-ark") else "solid"
         plt.plot(xs, ys, label=group["group"], marker='o', linestyle=style)
+        plt.fill_between(xs, down, up, alpha=0.3)
 
     plt.xlabel("degree")
     plt.ylabel("time (in ns)")