Added atmosphere component to the documentation

docs/dymos_book/examples/reentry/reentry.ipynb

@@ -135,6 +135,56 @@
     "Below is the code for the atmospheric component:"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import numpy as np\n",
+    "import openmdao.api as om\n",
+    "\n",
+    "\n",
+    "class Atmosphere(om.ExplicitComponent):\n",
+    "    \"\"\"\n",
+    "    Defines the logarithmic atmosphere model for the shuttle reentry problem.\n",
+    "\n",
+    "    References\n",
+    "    ----------\n",
+    "    .. [1] Betts, John T., Practical Methods for Optimal Control and Estimation Using Nonlinear\n",
+    "           Programming, p. 248, 2010.\n",
+    "    \"\"\"\n",
+    "\n",
+    "    def initialize(self):\n",
+    "        self.options.declare('num_nodes', types=int)\n",
+    "\n",
+    "    def setup(self):\n",
+    "        nn = self.options['num_nodes']\n",
+    "        self.add_input('h', val=np.ones(nn), desc='altitude', units='ft')\n",
+    "        self.add_output('rho', val=np.ones(nn), desc='local density', units='slug/ft**3')\n",
+    "        partial_range = np.arange(nn, dtype=int)\n",
+    "        self.declare_partials('rho', 'h', rows=partial_range, cols=partial_range)\n",
+    "\n",
+    "    def compute(self, inputs, outputs):\n",
+    "        h = inputs['h']\n",
+    "        h_r = 23800\n",
+    "        rho_0 = .002378\n",
+    "        outputs['rho'] = rho_0 * np.exp(-h / h_r)\n",
+    "\n",
+    "    def compute_partials(self, inputs, partials):\n",
+    "        h = inputs['h']\n",
+    "        h_r = 23800\n",
+    "        rho_0 = .002378\n",
+    "        partials['rho', 'h'] = -1 / h_r * rho_0 * np.exp(-h / h_r)\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Below is the code for the aerodynamics component:"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -706,7 +756,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.11.0"
   }
  },
  "nbformat": 4,