Notebook: use same order for APE formula as in code.

Closes: #553

notebooks/metrics.py_API_Documentation.ipynb

@@ -185,7 +185,7 @@
     "\n",
     "APE is based on the absolute relative pose between two poses $P_{ref,i}, P_{est,i} \\in \\mathrm{SE}(3)$ at timestamp $i$:\n",
     "\\begin{equation*}\n",
-    "E_i = P_{est,i} \\ominus P_{ref,i} = P_{ref,i}^{-1} P_{est,i} \\in \\mathrm{SE}(3)\n",
+    "E_i = P_{est,i} \\ominus P_{ref,i} = P_{est,i}^{-1} P_{ref,i} \\in \\mathrm{SE}(3)\n",
     "\\end{equation*}\n",
     "where $\\ominus$ is the inverse compositional operator, which takes two poses and gives the relative pose [Lu-1997].\n",
     "You can use different pose relations to calculate the APE:\n",