feature : 30 / 00 add ipywidgets interactive slider for Riemann sum

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: beachdweller

30_num_int/00_zeroth_order.ipynb

@@ -361,6 +361,23 @@
     "\n"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "source": "### 대화형 탐색<br>Interactive Exploration\n\n분할 수 $n$ 을 바꾸어 가며 직사각형이 반원에 어떻게 근사하는지 관찰해 보자.<br>\nChange the number of partitions $n$ and observe how the rectangles approximate the half circle.",
+   "metadata": {}
+  },
+  {
+   "cell_type": "code",
+   "source": "from ipywidgets import interact, IntSlider\n\n\ndef plot_num_int_0(n):\n    x_curve = py.sort(r * py.cos(py.deg2rad(py.linspace(0, 180, 256))))\n    y_curve = py.sqrt(r**2 - x_curve**2)\n\n    x_bar = py.linspace(-r, r, n + 1)\n    y_bar = py.sqrt(py.abs(r**2 - x_bar**2))\n    dx = x_bar[1] - x_bar[0]\n\n    py.fill_between(x_curve, y_curve, alpha=0.3)\n    py.bar(x_bar[:-1], y_bar[:-1], width=dx, alpha=0.5, align='edge', edgecolor='k')\n\n    area = sum(y_bar[:-1]) * dx\n    py.title(f'n = {n},  Area = {area:.6f},  Error = {abs(area - 1):.2e}')\n    py.axis('equal')\n    py.grid(True)\n    py.show()\n\n\ninteract(plot_num_int_0, n=IntSlider(min=2, max=200, step=1, value=10,\n                                      description='n :'));",
+   "metadata": {},
+   "execution_count": null,
+   "outputs": []
+  },
+  {
+   "cell_type": "markdown",
+   "source": "$n$을 2에서 200까지 바꾸어 보자. 오차가 어떻게 줄어드는가?<br>\nTry changing $n$ from 2 to 200. How does the error decrease?",
+   "metadata": {}
+  },
   {
    "cell_type": "markdown",
    "metadata": {},