Update the non-featured version of the recipe, as requested by Cyrille

Author: moble

notebooks/chapter09_numoptim/04_energy.ipynb

@@ -168,6 +168,13 @@
    },
    "outputs": [],
    "source": [
+    "def spring_color_map(c):\n",
+    "    min_c, max_c = -0.00635369422326, 0.00836362559722\n",
+    "    ratio = (max_c-c) / (max_c-min_c)\n",
+    "    color = plt.cm.coolwarm(ratio)\n",
+    "    shading = np.sqrt(abs(ratio-0.5)*2)\n",
+    "    return (shading*color[0], shading*color[1], shading*color[2], color[3])\n",
+    "\n",
     "def show_bar(P):\n",
     "    plt.figure(figsize=(5,4));\n",
     "    # Wall.\n",
@@ -180,7 +187,7 @@
     "        # is proportional to the spring elongation.\n",
     "        c = D[i,j] - L[i,j]\n",
     "        plt.plot(P[[i,j],0], P[[i,j],1], \n",
-    "                 lw=2, color=plt.cm.copper(c*150));\n",
+    "                 lw=2, color=spring_color_map(c));\n",
     "    # We plot the masses.\n",
     "    plt.plot(P[[I,J],0], P[[I,J],1], 'ok',);\n",
     "    # We configure the axes.\n",
@@ -338,7 +345,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.4.2"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,