Added function to make plots of LBB stability

demo/lbb-stability/make_plots.py

@@ -0,0 +1,25 @@
+import json
+import argparse
+import numpy as np
+import matplotlib.pyplot as plt
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--input")
+parser.add_argument("--output")
+args = parser.parse_args()
+
+with open(args.input, "r") as input_file:
+    data = json.load(input_file)
+
+fig, ax = plt.subplots()
+ax.set_title("Empirical inf-sup constants")
+ax.set_xscale("log", base=2)
+ax.set_ylim((0.0, 1.0))
+ax.set_xlabel("Mesh spacing")
+ax.set_ylabel("inf-sup constant")
+for entry in data:
+    element = entry["element"]
+    hs, λs = zip(*entry["results"])
+    ax.scatter(hs, λs, label=element)
+ax.legend()
+fig.savefig(args.output, bbox_inches="tight")